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authorLinus Torvalds2020-08-03 14:58:38 -0700
committerLinus Torvalds2020-08-03 14:58:38 -0700
commite4cbce4d131753eca271d9d67f58c6377f27ad21 (patch)
treee08e3c8836cd7b9f800e209131aed70897f5fe07
parentb34133fec882d2717f2d61a2a010edd3422368c8 (diff)
parent949bcb8135a96a6923e676646bd29cbe69e8350f (diff)
Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: - Improve uclamp performance by using a static key for the fast path - Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for better power efficiency of RT tasks on battery powered devices. (The default is to maximize performance & reduce RT latencies.) - Improve utime and stime tracking accuracy, which had a fixed boundary of error, which created larger and larger relative errors as the values become larger. This is now replaced with more precise arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h. - Improve the deadline scheduler, such as making it capacity aware - Improve frequency-invariant scheduling - Misc cleanups in energy/power aware scheduling - Add sched_update_nr_running tracepoint to track changes to nr_running - Documentation additions and updates - Misc cleanups and smaller fixes * tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits) sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst sched/doc: Document capacity aware scheduling sched: Document arch_scale_*_capacity() arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE Documentation/sysctl: Document uclamp sysctl knobs sched/uclamp: Add a new sysctl to control RT default boost value sched/uclamp: Fix a deadlock when enabling uclamp static key sched: Remove duplicated tick_nohz_full_enabled() check sched: Fix a typo in a comment sched/uclamp: Remove unnecessary mutex_init() arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry arch_topology, sched/core: Cleanup thermal pressure definition trace/events/sched.h: fix duplicated word linux/sched/mm.h: drop duplicated words in comments smp: Fix a potential usage of stale nr_cpus sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal sched: nohz: stop passing around unused "ticks" parameter. sched: Better document ttwu() sched: Add a tracepoint to track rq->nr_running ...
-rw-r--r--Documentation/admin-guide/sysctl/kernel.rst54
-rw-r--r--Documentation/scheduler/index.rst1
-rw-r--r--Documentation/scheduler/sched-capacity.rst439
-rw-r--r--Documentation/scheduler/sched-energy.rst12
-rw-r--r--arch/arm/include/asm/topology.h3
-rw-r--r--arch/arm64/include/asm/topology.h3
-rw-r--r--arch/x86/include/asm/div64.h14
-rw-r--r--arch/x86/include/asm/topology.h2
-rw-r--r--arch/x86/kernel/smpboot.c50
-rw-r--r--drivers/base/arch_topology.c11
-rw-r--r--drivers/pci/pci-driver.c5
-rw-r--r--include/asm-generic/vmlinux.lds.h24
-rw-r--r--include/linux/arch_topology.h4
-rw-r--r--include/linux/math64.h2
-rw-r--r--include/linux/psi_types.h7
-rw-r--r--include/linux/sched.h25
-rw-r--r--include/linux/sched/isolation.h1
-rw-r--r--include/linux/sched/loadavg.h2
-rw-r--r--include/linux/sched/mm.h8
-rw-r--r--include/linux/sched/sysctl.h4
-rw-r--r--include/linux/sched/task.h1
-rw-r--r--include/linux/sched/topology.h17
-rw-r--r--include/trace/events/sched.h14
-rw-r--r--init/Kconfig17
-rw-r--r--kernel/fork.c1
-rw-r--r--kernel/kthread.c6
-rw-r--r--kernel/sched/core.c466
-rw-r--r--kernel/sched/cpudeadline.c24
-rw-r--r--kernel/sched/cpufreq_schedutil.c2
-rw-r--r--kernel/sched/cputime.c46
-rw-r--r--kernel/sched/deadline.c118
-rw-r--r--kernel/sched/fair.c93
-rw-r--r--kernel/sched/idle.c11
-rw-r--r--kernel/sched/isolation.c3
-rw-r--r--kernel/sched/loadavg.c2
-rw-r--r--kernel/sched/pelt.c6
-rw-r--r--kernel/sched/pelt.h5
-rw-r--r--kernel/sched/psi.c113
-rw-r--r--kernel/sched/rt.c4
-rw-r--r--kernel/sched/sched.h126
-rw-r--r--kernel/sched/stop_task.c12
-rw-r--r--kernel/sched/topology.c2
-rw-r--r--kernel/smp.c3
-rw-r--r--kernel/sysctl.c21
-rw-r--r--kernel/time/timekeeping.c2
-rw-r--r--lib/cpumask.c16
-rw-r--r--lib/math/div64.c41
-rw-r--r--net/core/net-sysfs.c10
48 files changed, 1521 insertions, 332 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 83acf5025488..55bf6b4de4ec 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1062,6 +1062,60 @@ Enables/disables scheduler statistics. Enabling this feature
incurs a small amount of overhead in the scheduler but is
useful for debugging and performance tuning.
+sched_util_clamp_min:
+=====================
+
+Max allowed *minimum* utilization.
+
+Default value is 1024, which is the maximum possible value.
+
+It means that any requested uclamp.min value cannot be greater than
+sched_util_clamp_min, i.e., it is restricted to the range
+[0:sched_util_clamp_min].
+
+sched_util_clamp_max:
+=====================
+
+Max allowed *maximum* utilization.
+
+Default value is 1024, which is the maximum possible value.
+
+It means that any requested uclamp.max value cannot be greater than
+sched_util_clamp_max, i.e., it is restricted to the range
+[0:sched_util_clamp_max].
+
+sched_util_clamp_min_rt_default:
+================================
+
+By default Linux is tuned for performance. Which means that RT tasks always run
+at the highest frequency and most capable (highest capacity) CPU (in
+heterogeneous systems).
+
+Uclamp achieves this by setting the requested uclamp.min of all RT tasks to
+1024 by default, which effectively boosts the tasks to run at the highest
+frequency and biases them to run on the biggest CPU.
+
+This knob allows admins to change the default behavior when uclamp is being
+used. In battery powered devices particularly, running at the maximum
+capacity and frequency will increase energy consumption and shorten the battery
+life.
+
+This knob is only effective for RT tasks which the user hasn't modified their
+requested uclamp.min value via sched_setattr() syscall.
+
+This knob will not escape the range constraint imposed by sched_util_clamp_min
+defined above.
+
+For example if
+
+ sched_util_clamp_min_rt_default = 800
+ sched_util_clamp_min = 600
+
+Then the boost will be clamped to 600 because 800 is outside of the permissible
+range of [0:600]. This could happen for instance if a powersave mode will
+restrict all boosts temporarily by modifying sched_util_clamp_min. As soon as
+this restriction is lifted, the requested sched_util_clamp_min_rt_default
+will take effect.
seccomp
=======
diff --git a/Documentation/scheduler/index.rst b/Documentation/scheduler/index.rst
index 69074e5de9c4..88900aabdbf7 100644
--- a/Documentation/scheduler/index.rst
+++ b/Documentation/scheduler/index.rst
@@ -12,6 +12,7 @@ Linux Scheduler
sched-deadline
sched-design-CFS
sched-domains
+ sched-capacity
sched-energy
sched-nice-design
sched-rt-group
diff --git a/Documentation/scheduler/sched-capacity.rst b/Documentation/scheduler/sched-capacity.rst
new file mode 100644
index 000000000000..00bf0d011e2a
--- /dev/null
+++ b/Documentation/scheduler/sched-capacity.rst
@@ -0,0 +1,439 @@
+=========================
+Capacity Aware Scheduling
+=========================
+
+1. CPU Capacity
+===============
+
+1.1 Introduction
+----------------
+
+Conventional, homogeneous SMP platforms are composed of purely identical
+CPUs. Heterogeneous platforms on the other hand are composed of CPUs with
+different performance characteristics - on such platforms, not all CPUs can be
+considered equal.
+
+CPU capacity is a measure of the performance a CPU can reach, normalized against
+the most performant CPU in the system. Heterogeneous systems are also called
+asymmetric CPU capacity systems, as they contain CPUs of different capacities.
+
+Disparity in maximum attainable performance (IOW in maximum CPU capacity) stems
+from two factors:
+
+- not all CPUs may have the same microarchitecture (µarch).
+- with Dynamic Voltage and Frequency Scaling (DVFS), not all CPUs may be
+ physically able to attain the higher Operating Performance Points (OPP).
+
+Arm big.LITTLE systems are an example of both. The big CPUs are more
+performance-oriented than the LITTLE ones (more pipeline stages, bigger caches,
+smarter predictors, etc), and can usually reach higher OPPs than the LITTLE ones
+can.
+
+CPU performance is usually expressed in Millions of Instructions Per Second
+(MIPS), which can also be expressed as a given amount of instructions attainable
+per Hz, leading to::
+
+ capacity(cpu) = work_per_hz(cpu) * max_freq(cpu)
+
+1.2 Scheduler terms
+-------------------
+
+Two different capacity values are used within the scheduler. A CPU's
+``capacity_orig`` is its maximum attainable capacity, i.e. its maximum
+attainable performance level. A CPU's ``capacity`` is its ``capacity_orig`` to
+which some loss of available performance (e.g. time spent handling IRQs) is
+subtracted.
+
+Note that a CPU's ``capacity`` is solely intended to be used by the CFS class,
+while ``capacity_orig`` is class-agnostic. The rest of this document will use
+the term ``capacity`` interchangeably with ``capacity_orig`` for the sake of
+brevity.
+
+1.3 Platform examples
+---------------------
+
+1.3.1 Identical OPPs
+~~~~~~~~~~~~~~~~~~~~
+
+Consider an hypothetical dual-core asymmetric CPU capacity system where
+
+- work_per_hz(CPU0) = W
+- work_per_hz(CPU1) = W/2
+- all CPUs are running at the same fixed frequency
+
+By the above definition of capacity:
+
+- capacity(CPU0) = C
+- capacity(CPU1) = C/2
+
+To draw the parallel with Arm big.LITTLE, CPU0 would be a big while CPU1 would
+be a LITTLE.
+
+With a workload that periodically does a fixed amount of work, you will get an
+execution trace like so::
+
+ CPU0 work ^
+ | ____ ____ ____
+ | | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+ CPU1 work ^
+ | _________ _________ ____
+ | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+CPU0 has the highest capacity in the system (C), and completes a fixed amount of
+work W in T units of time. On the other hand, CPU1 has half the capacity of
+CPU0, and thus only completes W/2 in T.
+
+1.3.2 Different max OPPs
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Usually, CPUs of different capacity values also have different maximum
+OPPs. Consider the same CPUs as above (i.e. same work_per_hz()) with:
+
+- max_freq(CPU0) = F
+- max_freq(CPU1) = 2/3 * F
+
+This yields:
+
+- capacity(CPU0) = C
+- capacity(CPU1) = C/3
+
+Executing the same workload as described in 1.3.1, which each CPU running at its
+maximum frequency results in::
+
+ CPU0 work ^
+ | ____ ____ ____
+ | | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+ workload on CPU1
+ CPU1 work ^
+ | ______________ ______________ ____
+ | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+1.4 Representation caveat
+-------------------------
+
+It should be noted that having a *single* value to represent differences in CPU
+performance is somewhat of a contentious point. The relative performance
+difference between two different µarchs could be X% on integer operations, Y% on
+floating point operations, Z% on branches, and so on. Still, results using this
+simple approach have been satisfactory for now.
+
+2. Task utilization
+===================
+
+2.1 Introduction
+----------------
+
+Capacity aware scheduling requires an expression of a task's requirements with
+regards to CPU capacity. Each scheduler class can express this differently, and
+while task utilization is specific to CFS, it is convenient to describe it here
+in order to introduce more generic concepts.
+
+Task utilization is a percentage meant to represent the throughput requirements
+of a task. A simple approximation of it is the task's duty cycle, i.e.::
+
+ task_util(p) = duty_cycle(p)
+
+On an SMP system with fixed frequencies, 100% utilization suggests the task is a
+busy loop. Conversely, 10% utilization hints it is a small periodic task that
+spends more time sleeping than executing. Variable CPU frequencies and
+asymmetric CPU capacities complexify this somewhat; the following sections will
+expand on these.
+
+2.2 Frequency invariance
+------------------------
+
+One issue that needs to be taken into account is that a workload's duty cycle is
+directly impacted by the current OPP the CPU is running at. Consider running a
+periodic workload at a given frequency F::
+
+ CPU work ^
+ | ____ ____ ____
+ | | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+This yields duty_cycle(p) == 25%.
+
+Now, consider running the *same* workload at frequency F/2::
+
+ CPU work ^
+ | _________ _________ ____
+ | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+This yields duty_cycle(p) == 50%, despite the task having the exact same
+behaviour (i.e. executing the same amount of work) in both executions.
+
+The task utilization signal can be made frequency invariant using the following
+formula::
+
+ task_util_freq_inv(p) = duty_cycle(p) * (curr_frequency(cpu) / max_frequency(cpu))
+
+Applying this formula to the two examples above yields a frequency invariant
+task utilization of 25%.
+
+2.3 CPU invariance
+------------------
+
+CPU capacity has a similar effect on task utilization in that running an
+identical workload on CPUs of different capacity values will yield different
+duty cycles.
+
+Consider the system described in 1.3.2., i.e.::
+
+- capacity(CPU0) = C
+- capacity(CPU1) = C/3
+
+Executing a given periodic workload on each CPU at their maximum frequency would
+result in::
+
+ CPU0 work ^
+ | ____ ____ ____
+ | | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+ CPU1 work ^
+ | ______________ ______________ ____
+ | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+
+IOW,
+
+- duty_cycle(p) == 25% if p runs on CPU0 at its maximum frequency
+- duty_cycle(p) == 75% if p runs on CPU1 at its maximum frequency
+
+The task utilization signal can be made CPU invariant using the following
+formula::
+
+ task_util_cpu_inv(p) = duty_cycle(p) * (capacity(cpu) / max_capacity)
+
+with ``max_capacity`` being the highest CPU capacity value in the
+system. Applying this formula to the above example above yields a CPU
+invariant task utilization of 25%.
+
+2.4 Invariant task utilization
+------------------------------
+
+Both frequency and CPU invariance need to be applied to task utilization in
+order to obtain a truly invariant signal. The pseudo-formula for a task
+utilization that is both CPU and frequency invariant is thus, for a given
+task p::
+
+ curr_frequency(cpu) capacity(cpu)
+ task_util_inv(p) = duty_cycle(p) * ------------------- * -------------
+ max_frequency(cpu) max_capacity
+
+In other words, invariant task utilization describes the behaviour of a task as
+if it were running on the highest-capacity CPU in the system, running at its
+maximum frequency.
+
+Any mention of task utilization in the following sections will imply its
+invariant form.
+
+2.5 Utilization estimation
+--------------------------
+
+Without a crystal ball, task behaviour (and thus task utilization) cannot
+accurately be predicted the moment a task first becomes runnable. The CFS class
+maintains a handful of CPU and task signals based on the Per-Entity Load
+Tracking (PELT) mechanism, one of those yielding an *average* utilization (as
+opposed to instantaneous).
+
+This means that while the capacity aware scheduling criteria will be written
+considering a "true" task utilization (using a crystal ball), the implementation
+will only ever be able to use an estimator thereof.
+
+3. Capacity aware scheduling requirements
+=========================================
+
+3.1 CPU capacity
+----------------
+
+Linux cannot currently figure out CPU capacity on its own, this information thus
+needs to be handed to it. Architectures must define arch_scale_cpu_capacity()
+for that purpose.
+
+The arm and arm64 architectures directly map this to the arch_topology driver
+CPU scaling data, which is derived from the capacity-dmips-mhz CPU binding; see
+Documentation/devicetree/bindings/arm/cpu-capacity.txt.
+
+3.2 Frequency invariance
+------------------------
+
+As stated in 2.2, capacity-aware scheduling requires a frequency-invariant task
+utilization. Architectures must define arch_scale_freq_capacity(cpu) for that
+purpose.
+
+Implementing this function requires figuring out at which frequency each CPU
+have been running at. One way to implement this is to leverage hardware counters
+whose increment rate scale with a CPU's current frequency (APERF/MPERF on x86,
+AMU on arm64). Another is to directly hook into cpufreq frequency transitions,
+when the kernel is aware of the switched-to frequency (also employed by
+arm/arm64).
+
+4. Scheduler topology
+=====================
+
+During the construction of the sched domains, the scheduler will figure out
+whether the system exhibits asymmetric CPU capacities. Should that be the
+case:
+
+- The sched_asym_cpucapacity static key will be enabled.
+- The SD_ASYM_CPUCAPACITY flag will be set at the lowest sched_domain level that
+ spans all unique CPU capacity values.
+
+The sched_asym_cpucapacity static key is intended to guard sections of code that
+cater to asymmetric CPU capacity systems. Do note however that said key is
+*system-wide*. Imagine the following setup using cpusets::
+
+ capacity C/2 C
+ ________ ________
+ / \ / \
+ CPUs 0 1 2 3 4 5 6 7
+ \__/ \______________/
+ cpusets cs0 cs1
+
+Which could be created via:
+
+.. code-block:: sh
+
+ mkdir /sys/fs/cgroup/cpuset/cs0
+ echo 0-1 > /sys/fs/cgroup/cpuset/cs0/cpuset.cpus
+ echo 0 > /sys/fs/cgroup/cpuset/cs0/cpuset.mems
+
+ mkdir /sys/fs/cgroup/cpuset/cs1
+ echo 2-7 > /sys/fs/cgroup/cpuset/cs1/cpuset.cpus
+ echo 0 > /sys/fs/cgroup/cpuset/cs1/cpuset.mems
+
+ echo 0 > /sys/fs/cgroup/cpuset/cpuset.sched_load_balance
+
+Since there *is* CPU capacity asymmetry in the system, the
+sched_asym_cpucapacity static key will be enabled. However, the sched_domain
+hierarchy of CPUs 0-1 spans a single capacity value: SD_ASYM_CPUCAPACITY isn't
+set in that hierarchy, it describes an SMP island and should be treated as such.
+
+Therefore, the 'canonical' pattern for protecting codepaths that cater to
+asymmetric CPU capacities is to:
+
+- Check the sched_asym_cpucapacity static key
+- If it is enabled, then also check for the presence of SD_ASYM_CPUCAPACITY in
+ the sched_domain hierarchy (if relevant, i.e. the codepath targets a specific
+ CPU or group thereof)
+
+5. Capacity aware scheduling implementation
+===========================================
+
+5.1 CFS
+-------
+
+5.1.1 Capacity fitness
+~~~~~~~~~~~~~~~~~~~~~~
+
+The main capacity scheduling criterion of CFS is::
+
+ task_util(p) < capacity(task_cpu(p))
+
+This is commonly called the capacity fitness criterion, i.e. CFS must ensure a
+task "fits" on its CPU. If it is violated, the task will need to achieve more
+work than what its CPU can provide: it will be CPU-bound.
+
+Furthermore, uclamp lets userspace specify a minimum and a maximum utilization
+value for a task, either via sched_setattr() or via the cgroup interface (see
+Documentation/admin-guide/cgroup-v2.rst). As its name imply, this can be used to
+clamp task_util() in the previous criterion.
+
+5.1.2 Wakeup CPU selection
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+CFS task wakeup CPU selection follows the capacity fitness criterion described
+above. On top of that, uclamp is used to clamp the task utilization values,
+which lets userspace have more leverage over the CPU selection of CFS
+tasks. IOW, CFS wakeup CPU selection searches for a CPU that satisfies::
+
+ clamp(task_util(p), task_uclamp_min(p), task_uclamp_max(p)) < capacity(cpu)
+
+By using uclamp, userspace can e.g. allow a busy loop (100% utilization) to run
+on any CPU by giving it a low uclamp.max value. Conversely, it can force a small
+periodic task (e.g. 10% utilization) to run on the highest-performance CPUs by
+giving it a high uclamp.min value.
+
+.. note::
+
+ Wakeup CPU selection in CFS can be eclipsed by Energy Aware Scheduling
+ (EAS), which is described in Documentation/scheduling/sched-energy.rst.
+
+5.1.3 Load balancing
+~~~~~~~~~~~~~~~~~~~~
+
+A pathological case in the wakeup CPU selection occurs when a task rarely
+sleeps, if at all - it thus rarely wakes up, if at all. Consider::
+
+ w == wakeup event
+
+ capacity(CPU0) = C
+ capacity(CPU1) = C / 3
+
+ workload on CPU0
+ CPU work ^
+ | _________ _________ ____
+ | | | | | |
+ +----+----+----+----+----+----+----+----+----+----+-> time
+ w w w
+
+ workload on CPU1
+ CPU work ^
+ | ____________________________________________
+ | |
+ +----+----+----+----+----+----+----+----+----+----+->
+ w
+
+This workload should run on CPU0, but if the task either:
+
+- was improperly scheduled from the start (inaccurate initial
+ utilization estimation)
+- was properly scheduled from the start, but suddenly needs more
+ processing power
+
+then it might become CPU-bound, IOW ``task_util(p) > capacity(task_cpu(p))``;
+the CPU capacity scheduling criterion is violated, and there may not be any more
+wakeup event to fix this up via wakeup CPU selection.
+
+Tasks that are in this situation are dubbed "misfit" tasks, and the mechanism
+put in place to handle this shares the same name. Misfit task migration
+leverages the CFS load balancer, more specifically the active load balance part
+(which caters to migrating currently running tasks). When load balance happens,
+a misfit active load balance will be triggered if a misfit task can be migrated
+to a CPU with more capacity than its current one.
+
+5.2 RT
+------
+
+5.2.1 Wakeup CPU selection
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+RT task wakeup CPU selection searches for a CPU that satisfies::
+
+ task_uclamp_min(p) <= capacity(task_cpu(cpu))
+
+while still following the usual priority constraints. If none of the candidate
+CPUs can satisfy this capacity criterion, then strict priority based scheduling
+is followed and CPU capacities are ignored.
+
+5.3 DL
+------
+
+5.3.1 Wakeup CPU selection
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+DL task wakeup CPU selection searches for a CPU that satisfies::
+
+ task_bandwidth(p) < capacity(task_cpu(p))
+
+while still respecting the usual bandwidth and deadline constraints. If
+none of the candidate CPUs can satisfy this capacity criterion, then the
+task will remain on its current CPU.
diff --git a/Documentation/scheduler/sched-energy.rst b/Documentation/scheduler/sched-energy.rst
index 9580c57a52bc..78f850778982 100644
--- a/Documentation/scheduler/sched-energy.rst
+++ b/Documentation/scheduler/sched-energy.rst
@@ -331,16 +331,8 @@ asymmetric CPU topologies for now. This requirement is checked at run-time by
looking for the presence of the SD_ASYM_CPUCAPACITY flag when the scheduling
domains are built.
-The flag is set/cleared automatically by the scheduler topology code whenever
-there are CPUs with different capacities in a root domain. The capacities of
-CPUs are provided by arch-specific code through the arch_scale_cpu_capacity()
-callback. As an example, arm and arm64 share an implementation of this callback
-which uses a combination of CPUFreq data and device-tree bindings to compute the
-capacity of CPUs (see drivers/base/arch_topology.c for more details).
-
-So, in order to use EAS on your platform your architecture must implement the
-arch_scale_cpu_capacity() callback, and some of the CPUs must have a lower
-capacity than others.
+See Documentation/sched/sched-capacity.rst for requirements to be met for this
+flag to be set in the sched_domain hierarchy.
Please note that EAS is not fundamentally incompatible with SMP, but no
significant savings on SMP platforms have been observed yet. This restriction
diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
index 435aba289fc5..e0593cf095d0 100644
--- a/arch/arm/include/asm/topology.h
+++ b/arch/arm/include/asm/topology.h
@@ -16,8 +16,9 @@
/* Enable topology flag updates */
#define arch_update_cpu_topology topology_update_cpu_topology
-/* Replace task scheduler's default thermal pressure retrieve API */
+/* Replace task scheduler's default thermal pressure API */
#define arch_scale_thermal_pressure topology_get_thermal_pressure
+#define arch_set_thermal_pressure topology_set_thermal_pressure
#else
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
index 0cc835ddfcd1..e042f6527981 100644
--- a/arch/arm64/include/asm/topology.h
+++ b/arch/arm64/include/asm/topology.h
@@ -34,8 +34,9 @@ void topology_scale_freq_tick(void);
/* Enable topology flag updates */
#define arch_update_cpu_topology topology_update_cpu_topology
-/* Replace task scheduler's default thermal pressure retrieve API */
+/* Replace task scheduler's default thermal pressure API */
#define arch_scale_thermal_pressure topology_get_thermal_pressure
+#define arch_set_thermal_pressure topology_set_thermal_pressure
#include <asm-generic/topology.h>
diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h
index 9b8cb50768c2..b8f1dc0761e4 100644
--- a/arch/x86/include/asm/div64.h
+++ b/arch/x86/include/asm/div64.h
@@ -74,16 +74,26 @@ static inline u64 mul_u32_u32(u32 a, u32 b)
#else
# include <asm-generic/div64.h>
-static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
+/*
+ * Will generate an #DE when the result doesn't fit u64, could fix with an
+ * __ex_table[] entry when it becomes an issue.
+ */
+static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div)
{
u64 q;
asm ("mulq %2; divq %3" : "=a" (q)
- : "a" (a), "rm" ((u64)mul), "rm" ((u64)div)
+ : "a" (a), "rm" (mul), "rm" (div)
: "rdx");
return q;
}
+#define mul_u64_u64_div_u64 mul_u64_u64_div_u64
+
+static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
+{
+ return mul_u64_u64_div_u64(a, mul, div);
+}
#define mul_u64_u32_div mul_u64_u32_div
#endif /* CONFIG_X86_32 */
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 79d8d5496330..f4234575f3fd 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -193,7 +193,7 @@ static inline void sched_clear_itmt_support(void)
}
#endif /* CONFIG_SCHED_MC_PRIO */
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && defined(CONFIG_X86_64)
#include <asm/cpufeature.h>
DECLARE_STATIC_KEY_FALSE(arch_scale_freq_key);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index ffbd9a3d78d8..518ac6bf752e 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -56,6 +56,7 @@
#include <linux/cpuidle.h>
#include <linux/numa.h>
#include <linux/pgtable.h>
+#include <linux/overflow.h>
#include <asm/acpi.h>
#include <asm/desc.h>
@@ -1777,6 +1778,7 @@ void native_play_dead(void)
#endif
+#ifdef CONFIG_X86_64
/*
* APERF/MPERF frequency ratio computation.
*
@@ -1975,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
static bool intel_set_max_freq_ratio(void)
{
u64 base_freq, turbo_freq;
+ u64 turbo_ratio;
if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
goto out;
@@ -2000,15 +2003,23 @@ out:
/*
* Some hypervisors advertise X86_FEATURE_APERFMPERF
* but then fill all MSR's with zeroes.
+ * Some CPUs have turbo boost but don't declare any turbo ratio
+ * in MSR_TURBO_RATIO_LIMIT.
*/
- if (!base_freq) {
- pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n");
+ if (!base_freq || !turbo_freq) {
+ pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n");
return false;
}
- arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE,
- base_freq);
+ turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
+ if (!turbo_ratio) {
+ pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
+ return false;
+ }
+
+ arch_turbo_freq_ratio = turbo_ratio;
arch_set_max_freq_ratio(turbo_disabled());
+
return true;
}
@@ -2048,11 +2059,19 @@ static void init_freq_invariance(bool secondary)
}
}
+static void disable_freq_invariance_workfn(struct work_struct *work)
+{
+ static_branch_disable(&arch_scale_freq_key);
+}
+
+static DECLARE_WORK(disable_freq_invariance_work,
+ disable_freq_invariance_workfn);
+
DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
void arch_scale_freq_tick(void)
{
- u64 freq_scale;
+ u64 freq_scale = SCHED_CAPACITY_SCALE;
u64 aperf, mperf;
u64 acnt, mcnt;
@@ -2064,19 +2083,32 @@ void arch_scale_freq_tick(void)
acnt = aperf - this_cpu_read(arch_prev_aperf);
mcnt = mperf - this_cpu_read(arch_prev_mperf);
- if (!mcnt)
- return;
this_cpu_write(arch_prev_aperf, aperf);
this_cpu_write(arch_prev_mperf, mperf);
- acnt <<= 2*SCHED_CAPACITY_SHIFT;
- mcnt *= arch_max_freq_ratio;
+ if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
+ goto error;
+
+ if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt)
+ goto error;
freq_scale = div64_u64(acnt, mcnt);
+ if (!freq_scale)
+ goto error;
if (freq_scale > SCHED_CAPACITY_SCALE)
freq_scale = SCHED_CAPACITY_SCALE;
this_cpu_write(arch_freq_scale, freq_scale);
+ return;
+
+error:
+ pr_warn("Scheduler frequency invariance went wobbly, disabling!\n");
+ schedule_work(&disable_freq_invariance_work);
+}
+#else
+static inline void init_freq_invariance(bool secondary)
+{
}
+#endif /* CONFIG_X86_64 */
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 4d0a0038b476..75f72d684294 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -54,6 +54,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
per_cpu(cpu_scale, cpu) = capacity;
}
+DEFINE_PER_CPU(unsigned long, thermal_pressure);
+
+void topology_set_thermal_pressure(const struct cpumask *cpus,
+ unsigned long th_pressure)
+{
+ int cpu;
+
+ for_each_cpu(cpu, cpus)
+ WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure);
+}
+
static ssize_t cpu_capacity_show(struct device *dev,
struct device_attribute *attr,
char *buf)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index da6510af1221..449466f71040 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -12,6 +12,7 @@
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/sched/isolation.h>
#include <linux/cpu.h>
#include <linux/pm_runtime.h>
#include <linux/suspend.h>
@@ -333,6 +334,7 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
const struct pci_device_id *id)
{
int error, node, cpu;
+ int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
struct drv_dev_and_id ddi = { drv, dev, id };
/*
@@ -353,7 +355,8 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
pci_physfn_is_probed(dev))
cpu = nr_cpu_ids;
else
- cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
+ cpu = cpumask_any_and(cpumask_of_node(node),
+ housekeeping_cpumask(hk_flags));
if (cpu < nr_cpu_ids)
error = work_on_cpu(cpu, local_pci_probe, &ddi);
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 052e0f05a984..de8493cc3082 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -109,12 +109,31 @@
#endif
/*
- * Align to a 32 byte boundary equal to the
- * alignment gcc 4.5 uses for a struct
+ * GCC 4.5 and later have a 32 bytes section alignment for structures.
+ * Except GCC 4.9, that feels the need to align on 64 bytes.
*/
+#if __GNUC__ == 4 && __GNUC_MINOR__ == 9
+#define STRUCT_ALIGNMENT 64
+#else
#define STRUCT_ALIGNMENT 32
+#endif
#define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT)
+/*
+ * The order of the sched class addresses are important, as they are
+ * used to determine the order of the priority of each sched class in
+ * relation to each other.
+ */
+#define SCHED_DATA \
+ STRUCT_ALIGN(); \
+ __begin_sched_classes = .; \
+ *(__idle_sched_class) \
+ *(__fair_sched_class) \
+ *(__rt_sched_class) \
+ *(__dl_sched_class) \
+ *(__stop_sched_class) \
+ __end_sched_classes = .;
+
/* The actual configuration determine if the init/exit sections
* are handled as text/data or they can be discarded (which
* often happens at runtime)
@@ -389,6 +408,7 @@
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
__start_rodata = .; \
*(.rodata) *(.rodata.*) \
+ SCHED_DATA \
RO_AFTER_INIT_DATA /* Read only after init */ \
. = ALIGN(8); \
__start___tracepoints_ptrs = .; \
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 0566cb3314ef..69b1dabe39dc 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -39,8 +39,8 @@ static inline unsigned long topology_get_thermal_pressure(int cpu)
return per_cpu(thermal_pressure, cpu);
}
-void arch_set_thermal_pressure(struct cpumask *cpus,
- unsigned long th_pressure);
+void topology_set_thermal_pressure(const struct cpumask *cpus,
+ unsigned long th_pressure);
struct cpu_topology {
int thread_id;
diff --git a/include/linux/math64.h b/include/linux/math64.h
index 11a267413e8e..d097119419e6 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -263,6 +263,8 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
}
#endif /* mul_u64_u32_div */
+u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div);
+
#define DIV64_U64_ROUND_UP(ll, d) \
({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
index 4b7258495a04..b95f3211566a 100644
--- a/include/linux/psi_types.h
+++ b/include/linux/psi_types.h
@@ -153,9 +153,10 @@ struct psi_group {
unsigned long avg[NR_PSI_STATES - 1][3];
/* Monitor work control */
- atomic_t poll_scheduled;
- struct kthread_worker __rcu *poll_kworker;
- struct kthread_delayed_work poll_work;
+ struct task_struct __rcu *poll_task;
+ struct timer_list poll_timer;
+ wait_queue_head_t poll_wait;
+ atomic_t poll_wakeup;
/* Protects data used by the monitor */
struct mutex trigger_lock;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 060e9214c8b5..6d6683b48c2a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -155,24 +155,24 @@ struct task_group;
*
* for (;;) {
* set_current_state(TASK_UNINTERRUPTIBLE);
- * if (!need_sleep)
- * break;
+ * if (CONDITION)
+ * break;
*
* schedule();
* }
* __set_current_state(TASK_RUNNING);
*
* If the caller does not need such serialisation (because, for instance, the
- * condition test and condition change and wakeup are under the same lock) then
+ * CONDITION test and condition change and wakeup are under the same lock) then
* use __set_current_state().
*
* The above is typically ordered against the wakeup, which does:
*
- * need_sleep = false;
+ * CONDITION = 1;
* wake_up_state(p, TASK_UNINTERRUPTIBLE);
*
- * where wake_up_state() executes a full memory barrier before accessing the
- * task state.
+ * where wake_up_state()/try_to_wake_up() executes a full memory barrier before
+ * accessing p->state.
*
* Wakeup will do: if (@state & p->state) p->state = TASK_RUNNING, that is,
* once it observes the TASK_UNINTERRUPTIBLE store the waking CPU can issue a
@@ -375,7 +375,7 @@ struct util_est {
* For cfs_rq, they are the aggregated values of all runnable and blocked
* sched_entities.
*
- * The load/runnable/util_avg doesn't direcly factor frequency scaling and CPU
+ * The load/runnable/util_avg doesn't directly factor frequency scaling and CPU
* capacity scaling. The scaling is done through the rq_clock_pelt that is used
* for computing those signals (see update_rq_clock_pelt())
*
@@ -687,9 +687,15 @@ struct task_struct {
struct sched_dl_entity dl;
#ifdef CONFIG_UCLAMP_TASK
- /* Clamp values requested for a scheduling entity */
+ /*
+ * Clamp values requested for a scheduling entity.
+ * Must be updated with task_rq_lock() held.
+ */
struct uclamp_se uclamp_req[UCLAMP_CNT];
- /* Effective clamp values used for a scheduling entity */
+ /*
+ * Effective clamp values used for a scheduling entity.
+ * Must be updated with task_rq_lock() held.
+ */
struct uclamp_se uclamp[UCLAMP_CNT];
#endif
@@ -2039,6 +2045,7 @@ const struct sched_avg *sched_trace_rq_avg_dl(struct rq *rq);
const struct sched_avg *sched_trace_rq_avg_irq(struct rq *rq);
int sched_trace_rq_cpu(struct rq *rq);
+int sched_trace_rq_nr_running(struct rq *rq);
const struct cpumask *sched_trace_rd_span(struct root_domain *rd);
diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 0fbcbacd1b29..cc9f393e2a70 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -14,6 +14,7 @@ enum hk_flags {
HK_FLAG_DOMAIN = (1 << 5),
HK_FLAG_WQ = (1 << 6),
HK_FLAG_MANAGED_IRQ = (1 << 7),
+ HK_FLAG_KTHREAD = (1 << 8),
};
#ifdef CONFIG_CPU_ISOLATION
diff --git a/include/linux/sched/loadavg.h b/include/linux/sched/loadavg.h
index 4859bea47a7b..83ec54b65e79 100644
--- a/include/linux/sched/loadavg.h
+++ b/include/linux/sched/loadavg.h
@@ -43,6 +43,6 @@ extern unsigned long calc_load_n(unsigned long load, unsigned long exp,
#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
-extern void calc_global_load(unsigned long ticks);
+extern void calc_global_load(void);
#endif /* _LINUX_SCHED_LOADAVG_H */
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 480a4d1b7dd8..6be66f52a2ad 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -23,7 +23,7 @@ extern struct mm_struct *mm_alloc(void);
* will still exist later on and mmget_not_zero() has to be used before
* accessing it.
*
- * This is a preferred way to to pin @mm for a longer/unbounded amount
+ * This is a preferred way to pin @mm for a longer/unbounded amount
* of time.
*
* Use mmdrop() to release the reference acquired by mmgrab().
@@ -49,8 +49,6 @@ static inline void mmdrop(struct mm_struct *mm)
__mmdrop(mm);
}
-void mmdrop(struct mm_struct *mm);
-
/*
* This has to be called after a get_task_mm()/mmget_not_zero()
* followed by taking the mmap_lock for writing before modifying the
@@ -234,7 +232,7 @@ static inline unsigned int memalloc_noio_save(void)
* @flags: Flags to restore.
*
* Ends the implicit GFP_NOIO scope started by memalloc_noio_save function.
- * Always make sure that that the given flags is the return value from the
+ * Always make sure that the given flags is the return value from the
* pairing memalloc_noio_save call.
*/
static inline void memalloc_noio_restore(unsigned int flags)
@@ -265,7 +263,7 @@ static inline unsigned int memalloc_nofs_save(void)
* @flags: Flags to restore.
*
* Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function.
- * Always make sure that that the given flags is the return value from the
+ * Always make sure that the given flags is the return value from the
* pairing memalloc_nofs_save call.
*/
static inline void memalloc_nofs_restore(unsigned int flags)
diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 660ac49f2b53..3c31ba88aca5 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -61,9 +61,13 @@ int sched_proc_update_handler(struct ctl_table *table, int write,
extern unsigned int sysctl_sched_rt_period;
extern int sysctl_sched_rt_runtime;
+extern unsigned int sysctl_sched_dl_period_max;
+extern unsigned int sysctl_sched_dl_period_min;
+
#ifdef CONFIG_UCLAMP_TASK
extern unsigned int sysctl_sched_uclamp_util_min;
extern unsigned int sysctl_sched_uclamp_util_max;
+extern unsigned int sysctl_sched_uclamp_util_min_rt_default;
#endif
#ifdef CONFIG_CFS_BANDWIDTH
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 1301077f9c24..27b4fa454c80 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -55,6 +55,7 @@ extern asmlinkage void schedule_tail(struct task_struct *prev);
extern void init_idle(struct task_struct *idle, int cpu);
extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
+extern void sched_post_fork(struct task_struct *p);
extern void sched_dead(struct task_struct *p);
void __noreturn do_task_dead(void);
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h
index fb11091129b3..820511289857 100644
--- a/include/linux/sched/topology.h
+++ b/include/linux/sched/topology.h
@@ -217,6 +217,16 @@ static inline bool cpus_share_cache(int this_cpu, int that_cpu)
#endif /* !CONFIG_SMP */
#ifndef arch_scale_cpu_capacity
+/**
+ * arch_scale_cpu_capacity - get the capacity scale factor of a given CPU.
+ * @cpu: the CPU in question.
+ *
+ * Return: the CPU scale factor normalized against SCHED_CAPACITY_SCALE, i.e.
+ *
+ * max_perf(cpu)
+ * ----------------------------- * SCHED_CAPACITY_SCALE
+ * max(max_perf(c) : c \in CPUs)
+ */
static __always_inline
unsigned long arch_scale_cpu_capacity(int cpu)
{
@@ -232,6 +242,13 @@ unsigned long arch_scale_thermal_pressure(int cpu)
}
#endif
+#ifndef arch_set_thermal_pressure
+static __always_inline
+void arch_set_thermal_pressure(const struct cpumask *cpus,
+ unsigned long th_pressure)
+{ }
+#endif
+
static inline int task_node(const struct task_struct *p)
{
return cpu_to_node(task_cpu(p));
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index ed168b0e2c53..fec25b9cfbaf 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -91,7 +91,7 @@ DEFINE_EVENT(sched_wakeup_template, sched_waking,
/*
* Tracepoint called when the task is actually woken; p->state == TASK_RUNNNG.
- * It it not always called from the waking context.
+ * It is not always called from the waking context.
*/
DEFINE_EVENT(sched_wakeup_template, sched_wakeup,
TP_PROTO(struct task_struct *p),
@@ -634,6 +634,18 @@ DECLARE_TRACE(sched_overutilized_tp,
TP_PROTO(struct root_domain *rd, bool overutilized),
TP_ARGS(rd, overutilized));
+DECLARE_TRACE(sched_util_est_cfs_tp,
+ TP_PROTO(struct cfs_rq *cfs_rq),
+ TP_ARGS(cfs_rq));
+
+DECLARE_TRACE(sched_util_est_se_tp,
+ TP_PROTO(struct sched_entity *se),
+ TP_ARGS(se));
+
+DECLARE_TRACE(sched_update_nr_running_tp,
+ TP_PROTO(struct rq *rq, int change),
+ TP_ARGS(rq, change));
+
#endif /* _TRACE_SCHED_H */
/* This part must be outside protection */
diff --git a/init/Kconfig b/init/Kconfig
index 0498af567f70..9f7f249dab43 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -492,8 +492,23 @@ config HAVE_SCHED_AVG_IRQ
depends on SMP
config SCHED_THERMAL_PRESSURE
- bool "Enable periodic averaging of thermal pressure"
+ bool
+ default y if ARM && ARM_CPU_TOPOLOGY
+ default y if ARM64
depends on SMP
+ depends on CPU_FREQ_THERMAL
+ help
+ Select this option to enable thermal pressure accounting in the
+ scheduler. Thermal pressure is the value conveyed to the scheduler
+ that reflects the reduction in CPU compute capacity resulted from
+ thermal throttling. Thermal throttling occurs when the performance of
+ a CPU is capped due to high operating temperatures.
+
+ If selected, the scheduler will be able to balance tasks accordingly,
+ i.e. put less load on throttled CPUs than on non/less throttled ones.
+
+ This requires the architecture to implement
+ arch_set_thermal_pressure() and arch_get_thermal_pressure().
config BSD_PROCESS_ACCT
bool "BSD Process Accounting"
diff --git a/kernel/fork.c b/kernel/fork.c
index 0cc3d9cd6cc2..2a8e7287a558 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2302,6 +2302,7 @@ static __latent_entropy struct task_struct *copy_process(
write_unlock_irq(&tasklist_lock);
proc_fork_connector(p);
+ sched_post_fork(p);
cgroup_post_fork(p, args);
perf_event_fork(p);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 132f84a5fde3..1d9e2fdfd67a 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -27,6 +27,7 @@
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <linux/numa.h>
+#include <linux/sched/isolation.h>
#include <trace/events/sched.h>
@@ -383,7 +384,8 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
* The kernel thread should not inherit these properties.
*/
sched_setscheduler_nocheck(task, SCHED_NORMAL, &param);
- set_cpus_allowed_ptr(task, cpu_all_mask);
+ set_cpus_allowed_ptr(task,
+ housekeeping_cpumask(HK_FLAG_KTHREAD));
}
kfree(create);
return task;
@@ -608,7 +610,7 @@ int kthreadd(void *unused)
/* Setup a clean context for our children to inherit. */
set_task_comm(tsk, "kthreadd");
ignore_signals(tsk);
- set_cpus_allowed_ptr(tsk, cpu_all_mask);
+ set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_FLAG_KTHREAD));
set_mems_allowed(node_states[N_MEMORY]);
current->flags |= PF_NOFREEZE;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2142c6767682..4a0e7b449b88 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6,6 +6,10 @@
*
* Copyright (C) 1991-2002 Linus Torvalds
*/
+#define CREATE_TRACE_POINTS
+#include <trace/events/sched.h>
+#undef CREATE_TRACE_POINTS
+
#include "sched.h"
#include <linux/nospec.h>
@@ -23,9 +27,6 @@
#include "pelt.h"
#include "smp.h"
-#define CREATE_TRACE_POINTS
-#include <trace/events/sched.h>
-
/*
* Export tracepoints that act as a bare tracehook (ie: have no trace event
* associated with them) to allow external modules to probe them.
@@ -36,6 +37,9 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp);
EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp);
EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
@@ -75,6 +79,100 @@ __read_mostly int scheduler_running;
*/
int sysctl_sched_rt_runtime = 950000;
+
+/*
+ * Serialization rules:
+ *
+ * Lock order:
+ *
+ * p->pi_lock
+ * rq->lock
+ * hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls)
+ *
+ * rq1->lock
+ * rq2->lock where: rq1 < rq2
+ *
+ * Regular state:
+ *
+ * Normal scheduling state is serialized by rq->lock. __schedule() takes the
+ * local CPU's rq->lock, it optionally removes the task from the runqueue and
+ * always looks at the local rq data structures to find the most elegible task
+ * to run next.
+ *
+ * Task enqueue is also under rq->lock, possibly taken from another CPU.
+ * Wakeups from another LLC domain might use an IPI to transfer the enqueue to
+ * the local CPU to avoid bouncing the runqueue state around [ see
+ * ttwu_queue_wakelist() ]
+ *
+ * Task wakeup, specifically wakeups that involve migration, are horribly
+ * complicated to avoid having to take two rq->locks.
+ *
+ * Special state:
+ *
+ * System-calls and anything external will use task_rq_lock() which acquires
+ * both p->pi_lock and rq->lock. As a consequence the state they change is
+ * stable while holding either lock:
+ *
+ * - sched_setaffinity()/
+ * set_cpus_allowed_ptr(): p->cpus_ptr, p->nr_cpus_allowed
+ * - set_user_nice(): p->se.load, p->*prio
+ * - __sched_setscheduler(): p->sched_class, p->policy, p->*prio,
+ * p->se.load, p->rt_priority,
+ * p->dl.dl_{runtime, deadline, period, flags, bw, density}
+ * - sched_setnuma(): p->numa_preferred_nid
+ * - sched_move_task()/
+ * cpu_cgroup_fork(): p->sched_task_group
+ * - uclamp_update_active() p->uclamp*
+ *
+ * p->state <- TASK_*:
+ *
+ * is changed locklessly using set_current_state(), __set_current_state() or
+ * set_special_state(), see their respective comments, or by
+ * try_to_wake_up(). This latter uses p->pi_lock to serialize against
+ * concurrent self.
+ *
+ * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }:
+ *
+ * is set by activate_task() and cleared by deactivate_task(), under
+ * rq->lock. Non-zero indicates the task is runnable, the special
+ * ON_RQ_MIGRATING state is used for migration without holding both
+ * rq->locks. It indicates task_cpu() is not stable, see task_rq_lock().
+ *
+ * p->on_cpu <- { 0, 1 }:
+ *
+ * is set by prepare_task() and cleared by finish_task() such that it will be
+ * set before p is scheduled-in and cleared after p is scheduled-out, both
+ * under rq->lock. Non-zero indicates the task is running on its CPU.
+ *
+ * [ The astute reader will observe that it is possible for two tasks on one
+ * CPU to have ->on_cpu = 1 at the same time. ]
+ *
+ * task_cpu(p): is changed by set_task_cpu(), the rules are:
+ *
+ * - Don't call set_task_cpu() on a blocked task:
+ *
+ * We don't care what CPU we're not running on, this simplifies hotplug,
+ * the CPU assignment of blocked tasks isn't required to be valid.
+ *
+ * - for try_to_wake_up(), called under p->pi_lock:
+ *
+ * This allows try_to_wake_up() to only take one rq->lock, see its comment.
+ *
+ * - for migration called under rq->lock:
+ * [ see task_on_rq_migrating() in task_rq_lock() ]
+ *
+ * o move_queued_task()
+ * o detach_task()
+ *
+ * - for migration called under double_rq_lock():
+ *
+ * o __migrate_swap_task()
+ * o push_rt_task() / pull_rt_task()
+ * o push_dl_task() / pull_dl_task()
+ * o dl_task_offline_migration()
+ *
+ */
+
/*
* __task_rq_lock - lock the rq @p resides on.
*/
@@ -791,9 +889,46 @@ unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
/* Max allowed maximum utilization */
unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
+/*
+ * By default RT tasks run at the maximum performance point/capacity of the
+ * system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to
+ * SCHED_CAPACITY_SCALE.
+ *
+ * This knob allows admins to change the default behavior when uclamp is being
+ * used. In battery powered devices, particularly, running at the maximum
+ * capacity and frequency will increase energy consumption and shorten the
+ * battery life.
+ *
+ * This knob only affects RT tasks that their uclamp_se->user_defined == false.
+ *
+ * This knob will not override the system default sched_util_clamp_min defined
+ * above.
+ */
+unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
+
/* All clamps are required to be less or equal than these values */
static struct uclamp_se uclamp_default[UCLAMP_CNT];
+/*
+ * This static key is used to reduce the uclamp overhead in the fast path. It
+ * primarily disables the call to uclamp_rq_{inc, dec}() in
+ * enqueue/dequeue_task().
+ *
+ * This allows users to continue to enable uclamp in their kernel config with
+ * minimum uclamp overhead in the fast path.
+ *
+ * As soon as userspace modifies any of the uclamp knobs, the static key is
+ * enabled, since we have an actual users that make use of uclamp
+ * functionality.
+ *
+ * The knobs that would enable this static key are:
+ *
+ * * A task modifying its uclamp value with sched_setattr().
+ * * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs.
+ * * An admin modifying the cgroup cpu.uclamp.{min, max}
+ */
+DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
+
/* Integer rounded range for each bucket */
#define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
@@ -873,6 +1008,64 @@ unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id,
return uclamp_idle_value(rq, clamp_id, clamp_value);
}
+static void __uclamp_update_util_min_rt_default(struct task_struct *p)
+{
+ unsigned int default_util_min;
+ struct uclamp_se *uc_se;
+
+ lockdep_assert_held(&p->pi_lock);
+
+ uc_se = &p->uclamp_req[UCLAMP_MIN];
+
+ /* Only sync if user didn't override the default */
+ if (uc_se->user_defined)
+ return;
+
+ default_util_min = sysctl_sched_uclamp_util_min_rt_default;
+ uclamp_se_set(uc_se, default_util_min, false);
+}
+
+static void uclamp_update_util_min_rt_default(struct task_struct *p)
+{
+ struct rq_flags rf;
+ struct rq *rq;
+
+ if (!rt_task(p))
+ return;
+
+ /* Protect updates to p->uclamp_* */
+ rq = task_rq_lock(p, &rf);
+ __uclamp_update_util_min_rt_default(p);
+ task_rq_unlock(rq, p, &rf);
+}
+
+static void uclamp_sync_util_min_rt_default(void)
+{
+ struct task_struct *g, *p;
+
+ /*
+ * copy_process() sysctl_uclamp
+ * uclamp_min_rt = X;
+ * write_lock(&tasklist_lock) read_lock(&tasklist_lock)
+ * // link thread smp_mb__after_spinlock()
+ * write_unlock(&tasklist_lock) read_unlock(&tasklist_lock);
+ * sched_post_fork() for_each_process_thread()
+ * __uclamp_sync_rt() __uclamp_sync_rt()
+ *
+ * Ensures that either sched_post_fork() will observe the new
+ * uclamp_min_rt or for_each_process_thread() will observe the new
+ * task.
+ */
+ read_lock(&tasklist_lock);
+ smp_mb__after_spinlock();
+ read_unlock(&tasklist_lock);
+
+ rcu_read_lock();
+ for_each_process_thread(g, p)
+ uclamp_update_util_min_rt_default(p);
+ rcu_read_unlock();
+}
+
static inline struct uclamp_se
uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
{
@@ -990,10 +1183,38 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p,
lockdep_assert_held(&rq->lock);
+ /*
+ * If sched_uclamp_used was enabled after task @p was enqueued,
+ * we could end up with unbalanced call to uclamp_rq_dec_id().
+ *
+ * In this case the uc_se->active flag should be false since no uclamp
+ * accounting was performed at enqueue time and we can just return
+ * here.
+ *
+ * Need to be careful of the following enqeueue/dequeue ordering
+ * problem too
+ *
+ * enqueue(taskA)
+ * // sched_uclamp_used gets enabled
+ * enqueue(taskB)
+ * dequeue(taskA)
+ * // Must not decrement bukcet->tasks here
+ * dequeue(taskB)
+ *
+ * where we could end up with stale data in uc_se and
+ * bucket[uc_se->bucket_id].
+ *
+ * The following check here eliminates the possibility of such race.
+ */
+ if (unlikely(!uc_se->active))
+ return;
+
bucket = &uc_rq->bucket[uc_se->bucket_id];
+
SCHED_WARN_ON(!bucket->tasks);
if (likely(bucket->tasks))
bucket->tasks--;
+
uc_se->active = false;
/*
@@ -1021,6 +1242,15 @@ static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
{
enum uclamp_id clamp_id;
+ /*
+ * Avoid any overhead until uclamp is actually used by the userspace.
+ *
+ * The condition is constructed such that a NOP is generated when
+ * sched_uclamp_used is disabled.
+ */
+ if (!static_branch_unlikely(&sched_uclamp_used))
+ return;
+
if (unlikely(!p->sched_class->uclamp_enabled))
return;
@@ -1036,6 +1266,15 @@ static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
{
enum uclamp_id clamp_id;
+ /*
+ * Avoid any overhead until uclamp is actually used by the userspace.
+ *
+ * The condition is constructed such that a NOP is generated when
+ * sched_uclamp_used is disabled.
+ */
+ if (!static_branch_unlikely(&sched_uclamp_used))
+ return;
+
if (unlikely(!p->sched_class->uclamp_enabled))
return;
@@ -1114,12 +1353,13 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
bool update_root_tg = false;
- int old_min, old_max;
+ int old_min, old_max, old_min_rt;
int result;
mutex_lock(&uclamp_mutex);
old_min = sysctl_sched_uclamp_util_min;
old_max = sysctl_sched_uclamp_util_max;
+ old_min_rt = sysctl_sched_uclamp_util_min_rt_default;
result = proc_dointvec(table, write, buffer, lenp, ppos);
if (result)
@@ -1128,7 +1368,9 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
goto done;
if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max ||
- sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE) {
+ sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE ||
+ sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) {
+
result = -EINVAL;
goto undo;
}
@@ -1144,8 +1386,15 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
update_root_tg = true;
}
- if (update_root_tg)
+ if (update_root_tg) {
+ static_branch_enable(&sched_uclamp_used);
uclamp_update_root_tg();
+ }
+
+ if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) {
+ static_branch_enable(&sched_uclamp_used);
+ uclamp_sync_util_min_rt_default();
+ }
/*
* We update all RUNNABLE tasks only when task groups are in use.
@@ -1158,6 +1407,7 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
undo:
sysctl_sched_uclamp_util_min = old_min;
sysctl_sched_uclamp_util_max = old_max;
+ sysctl_sched_uclamp_util_min_rt_default = old_min_rt;
done:
mutex_unlock(&uclamp_mutex);
@@ -1180,6 +1430,15 @@ static int uclamp_validate(struct task_struct *p,
if (upper_bound > SCHED_CAPACITY_SCALE)
return -EINVAL;
+ /*
+ * We have valid uclamp attributes; make sure uclamp is enabled.
+ *
+ * We need to do that here, because enabling static branches is a
+ * blocking operation which obviously cannot be done while holding
+ * scheduler locks.
+ */
+ static_branch_enable(&sched_uclamp_used);
+
return 0;
}
@@ -1194,17 +1453,20 @@ static void __setscheduler_uclamp(struct task_struct *p,
*/
for_each_clamp_id(clamp_id) {
struct uclamp_se *uc_se = &p->uclamp_req[clamp_id];
- unsigned int clamp_value = uclamp_none(clamp_id);
/* Keep using defined clamps across class changes */
if (uc_se->user_defined)
continue;
- /* By default, RT tasks always get 100% boost */
+ /*
+ * RT by default have a 100% boost value that could be modified
+ * at runtime.
+ */
if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
- clamp_value = uclamp_none(UCLAMP_MAX);
+ __uclamp_update_util_min_rt_default(p);
+ else
+ uclamp_se_set(uc_se, uclamp_none(clamp_id), false);
- uclamp_se_set(uc_se, clamp_value, false);
}
if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
@@ -1225,6 +1487,10 @@ static void uclamp_fork(struct task_struct *p)
{
enum uclamp_id clamp_id;
+ /*
+ * We don't need to hold task_rq_lock() when updating p->uclamp_* here
+ * as the task is still at its early fork stages.
+ */
for_each_clamp_id(clamp_id)
p->uclamp[clamp_id].active = false;
@@ -1237,19 +1503,33 @@ static void uclamp_fork(struct task_struct *p)
}
}
+static void uclamp_post_fork(struct task_struct *p)
+{
+ uclamp_update_util_min_rt_default(p);
+}
+
+static void __init init_uclamp_rq(struct rq *rq)
+{
+ enum uclamp_id clamp_id;
+ struct uclamp_rq *uc_rq = rq->uclamp;
+
+ for_each_clamp_id(clamp_id) {
+ uc_rq[clamp_id] = (struct uclamp_rq) {
+ .value = uclamp_none(clamp_id)
+ };
+ }
+
+ rq->uclamp_flags = 0;
+}
+
static void __init init_uclamp(void)
{
struct uclamp_se uc_max = {};
enum uclamp_id clamp_id;
int cpu;
- mutex_init(&uclamp_mutex);
-
- for_each_possible_cpu(cpu) {
- memset(&cpu_rq(cpu)->uclamp, 0,
- sizeof(struct uclamp_rq)*UCLAMP_CNT);
- cpu_rq(cpu)->uclamp_flags = 0;
- }
+ for_each_possible_cpu(cpu)
+ init_uclamp_rq(cpu_rq(cpu));
for_each_clamp_id(clamp_id) {
uclamp_se_set(&init_task.uclamp_req[clamp_id],
@@ -1278,6 +1558,7 @@ static inline int uclamp_validate(struct task_struct *p,
static void __setscheduler_uclamp(struct task_struct *p,
const struct sched_attr *attr) { }
static inline void uclamp_fork(struct task_struct *p) { }
+static inline void uclamp_post_fork(struct task_struct *p) { }
static inline void init_uclamp(void) { }
#endif /* CONFIG_UCLAMP_TASK */
@@ -1404,20 +1685,10 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
{
- const struct sched_class *class;
-
- if (p->sched_class == rq->curr->sched_class) {
+ if (p->sched_class == rq->curr->sched_class)
rq->curr->sched_class->check_preempt_curr(rq, p, flags);
- } else {
- for_each_class(class) {
- if (class == rq->curr->sched_class)
- break;
- if (class == p->sched_class) {
- resched_curr(rq);
- break;
- }
- }
- }
+ else if (p->sched_class > rq->curr->sched_class)
+ resched_curr(rq);
/*
* A queue event has occurred, and we're going to schedule. In
@@ -1468,8 +1739,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
{
lockdep_assert_held(&rq->lock);
- WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING);
- dequeue_task(rq, p, DEQUEUE_NOCLOCK);
+ deactivate_task(rq, p, DEQUEUE_NOCLOCK);
set_task_cpu(p, new_cpu);
rq_unlock(rq, rf);
@@ -1477,8 +1747,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
rq_lock(rq, rf);
BUG_ON(task_cpu(p) != new_cpu);
- enqueue_task(rq, p, 0);
- p->on_rq = TASK_ON_RQ_QUEUED;
+ activate_task(rq, p, 0);
check_preempt_curr(rq, p, 0);
return rq;
@@ -2243,12 +2512,31 @@ ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
}
/*
- * Called in case the task @p isn't fully descheduled from its runqueue,
- * in this case we must do a remote wakeup. Its a 'light' wakeup though,
- * since all we need to do is flip p->state to TASK_RUNNING, since
- * the task is still ->on_rq.
+ * Consider @p being inside a wait loop:
+ *
+ * for (;;) {
+ * set_current_state(TASK_UNINTERRUPTIBLE);
+ *
+ * if (CONDITION)
+ * break;
+ *
+ * schedule();
+ * }
+ * __set_current_state(TASK_RUNNING);
+ *
+ * between set_current_state() and schedule(). In this case @p is still
+ * runnable, so all that needs doing is change p->state back to TASK_RUNNING in
+ * an atomic manner.
+ *
+ * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq
+ * then schedule() must still happen and p->state can be changed to
+ * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we
+ * need to do a full wakeup with enqueue.
+ *
+ * Returns: %true when the wakeup is done,
+ * %false otherwise.
*/
-static int ttwu_remote(struct task_struct *p, int wake_flags)
+static int ttwu_runnable(struct task_struct *p, int wake_flags)
{
struct rq_flags rf;
struct rq *rq;
@@ -2389,6 +2677,14 @@ static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
return false;
}
+
+#else /* !CONFIG_SMP */
+
+static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
+{
+ return false;
+}
+
#endif /* CONFIG_SMP */
static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
@@ -2396,10 +2692,8 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
struct rq *rq = cpu_rq(cpu);
struct rq_flags rf;
-#if defined(CONFIG_SMP)
if (ttwu_queue_wakelist(p, cpu, wake_flags))
return;
-#endif
rq_lock(rq, &rf);
update_rq_clock(rq);
@@ -2455,8 +2749,8 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
* migration. However the means are completely different as there is no lock
* chain to provide order. Instead we do:
*
- * 1) smp_store_release(X->on_cpu, 0)
- * 2) smp_cond_load_acquire(!X->on_cpu)
+ * 1) smp_store_release(X->on_cpu, 0) -- finish_task()
+ * 2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up()
*
* Example:
*
@@ -2496,15 +2790,33 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
* @state: the mask of task states that can be woken
* @wake_flags: wake modifier flags (WF_*)
*
- * If (@state & @p->state) @p->state = TASK_RUNNING.
+ * Conceptually does:
+ *
+ * If (@state & @p->state) @p->state = TASK_RUNNING.
*
* If the task was not queued/runnable, also place it back on a runqueue.
*
- * Atomic against schedule() which would dequeue a task, also see
- * set_current_state().
+ * This function is atomic against schedule() which would dequeue the task.
+ *
+ * It issues a full memory barrier before accessing @p->state, see the comment
+ * with set_current_state().
*
- * This function executes a full memory barrier before accessing the task
- * state; see set_current_state().
+ * Uses p->pi_lock to serialize against concurrent wake-ups.
+ *
+ * Relies on p->pi_lock stabilizing:
+ * - p->sched_class
+ * - p->cpus_ptr
+ * - p->sched_task_group
+ * in order to do migration, see its use of select_task_rq()/set_task_cpu().
+ *
+ * Tries really hard to only take one task_rq(p)->lock for performance.
+ * Takes rq->lock in:
+ * - ttwu_runnable() -- old rq, unavoidable, see comment there;
+ * - ttwu_queue() -- new rq, for enqueue of the task;
+ * - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us.
+ *
+ * As a consequence we race really badly with just about everything. See the
+ * many memory barriers and their comments for details.
*
* Return: %true if @p->state changes (an actual wakeup was done),
* %false otherwise.
@@ -2520,7 +2832,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
/*
* We're waking current, this means 'p->on_rq' and 'task_cpu(p)
* == smp_processor_id()'. Together this means we can special
- * case the whole 'p->on_rq && ttwu_remote()' case below
+ * case the whole 'p->on_rq && ttwu_runnable()' case below
* without taking any locks.
*
* In particular:
@@ -2541,8 +2853,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
/*
* If we are going to wake up a thread waiting for CONDITION we
* need to ensure that CONDITION=1 done by the caller can not be
- * reordered with p->state check below. This pairs with mb() in
- * set_current_state() the waiting thread does.
+ * reordered with p->state check below. This pairs with smp_store_mb()
+ * in set_current_state() that the waiting thread does.
*/
raw_spin_lock_irqsave(&p->pi_lock, flags);
smp_mb__after_spinlock();
@@ -2577,7 +2889,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* A similar smb_rmb() lives in try_invoke_on_locked_down_task().
*/
smp_rmb();
- if (READ_ONCE(p->on_rq) && ttwu_remote(p, wake_flags))
+ if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))
goto unlock;
if (p->in_iowait) {
@@ -2990,6 +3302,11 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
return 0;
}
+void sched_post_fork(struct task_struct *p)
+{
+ uclamp_post_fork(p);
+}
+
unsigned long to_ratio(u64 period, u64 runtime)
{
if (runtime == RUNTIME_INF)
@@ -3147,8 +3464,10 @@ static inline void prepare_task(struct task_struct *next)
/*
* Claim the task as running, we do this before switching to it
* such that any running task will have this set.
+ *
+ * See the ttwu() WF_ON_CPU case and its ordering comment.
*/
- next->on_cpu = 1;
+ WRITE_ONCE(next->on_cpu, 1);
#endif
}
@@ -3156,8 +3475,9 @@ static inline void finish_task(struct task_struct *prev)
{
#ifdef CONFIG_SMP
/*
- * After ->on_cpu is cleared, the task can be moved to a different CPU.
- * We must ensure this doesn't happen until the switch is completely
+ * This must be the very last reference to @prev from this CPU. After
+ * p->on_cpu is cleared, the task can be moved to a different CPU. We
+ * must ensure this doesn't happen until the switch is completely
* finished.
*
* In particular, the load of prev->state in finish_task_switch() must
@@ -3656,17 +3976,6 @@ unsigned long long task_sched_runtime(struct task_struct *p)
return ns;
}
-DEFINE_PER_CPU(unsigned long, thermal_pressure);
-
-void arch_set_thermal_pressure(struct cpumask *cpus,
- unsigned long th_pressure)
-{
- int cpu;
-
- for_each_cpu(cpu, cpus)
- WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure);
-}
-
/*
* This function gets called by the timer code, with HZ frequency.
* We call it with interrupts disabled.
@@ -4029,8 +4338,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
* higher scheduling class, because otherwise those loose the
* opportunity to pull in more work from other CPUs.
*/
- if (likely((prev->sched_class == &idle_sched_class ||
- prev->sched_class == &fair_sched_class) &&
+ if (likely(prev->sched_class <= &fair_sched_class &&
rq->nr_running == rq->cfs.h_nr_running)) {
p = pick_next_task_fair(rq, prev, rf);
@@ -5519,6 +5827,11 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
kattr.sched_nice = task_nice(p);
#ifdef CONFIG_UCLAMP_TASK
+ /*
+ * This could race with another potential updater, but this is fine
+ * because it'll correctly read the old or the new value. We don't need
+ * to guarantee who wins the race as long as it doesn't return garbage.
+ */
kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value;
kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value;
#endif
@@ -5876,7 +6189,7 @@ again:
if (task_running(p_rq, p) || p->state)
goto out_unlock;
- yielded = curr->sched_class->yield_to_task(rq, p, preempt);
+ yielded = curr->sched_class->yield_to_task(rq, p);
if (yielded) {
schedstat_inc(rq->yld_count);
/*
@@ -6710,6 +7023,14 @@ void __init sched_init(void)
unsigned long ptr = 0;
int i;
+ /* Make sure the linker didn't screw up */
+ BUG_ON(&idle_sched_class + 1 != &fair_sched_class ||
+ &fair_sched_class + 1 != &rt_sched_class ||
+ &rt_sched_class + 1 != &dl_sched_class);
+#ifdef CONFIG_SMP
+ BUG_ON(&dl_sched_class + 1 != &stop_sched_class);
+#endif
+
wait_bit_init();
#ifdef CONFIG_FAIR_GROUP_SCHED
@@ -7431,6 +7752,8 @@ static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
if (req.ret)
return req.ret;
+ static_branch_enable(&sched_uclamp_used);
+
mutex_lock(&uclamp_mutex);
rcu_read_lock();
@@ -8118,4 +8441,7 @@ const u32 sched_prio_to_wmult[40] = {
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
-#undef CREATE_TRACE_POINTS
+void call_trace_sched_update_nr_running(struct rq *rq, int count)
+{
+ trace_sched_update_nr_running_tp(rq, count);
+}
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 5cc4012572ec..8cb06c8c7eb1 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -121,6 +121,30 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
if (later_mask &&
cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) {
+ unsigned long cap, max_cap = 0;
+ int cpu, max_cpu = -1;
+
+ if (!static_branch_unlikely(&sched_asym_cpucapacity))
+ return 1;
+
+ /* Ensure the capacity of the CPUs fits the task. */
+ for_each_cpu(cpu, later_mask) {
+ if (!dl_task_fits_capacity(p, cpu)) {
+ cpumask_clear_cpu(cpu, later_mask);
+
+ cap = capacity_orig_of(cpu);
+
+ if (cap > max_cap ||
+ (cpu == task_cpu(p) && cap == max_cap)) {
+ max_cap = cap;
+ max_cpu = cpu;
+ }
+ }
+ }
+
+ if (cpumask_empty(later_mask))
+ cpumask_set_cpu(max_cpu, later_mask);
+
return 1;
} else {
int best_cpu = cpudl_maximum(cp);
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 7fbaee24c824..dc6835bc6490 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -210,7 +210,7 @@ unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
unsigned long dl_util, util, irq;
struct rq *rq = cpu_rq(cpu);
- if (!IS_BUILTIN(CONFIG_UCLAMP_TASK) &&
+ if (!uclamp_is_used() &&
type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
return max;
}
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index ff9435dee1df..5a55d2300452 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -520,50 +520,6 @@ void account_idle_ticks(unsigned long ticks)
}
/*
- * Perform (stime * rtime) / total, but avoid multiplication overflow by
- * losing precision when the numbers are big.
- */
-static u64 scale_stime(u64 stime, u64 rtime, u64 total)
-{
- u64 scaled;
-
- for (;;) {
- /* Make sure "rtime" is the bigger of stime/rtime */
- if (stime > rtime)
- swap(rtime, stime);
-
- /* Make sure 'total' fits in 32 bits */
- if (total >> 32)
- goto drop_precision;
-
- /* Does rtime (and thus stime) fit in 32 bits? */
- if (!(rtime >> 32))
- break;
-
- /* Can we just balance rtime/stime rather than dropping bits? */
- if (stime >> 31)
- goto drop_precision;
-
- /* We can grow stime and shrink rtime and try to make them both fit */
- stime <<= 1;
- rtime >>= 1;
- continue;
-
-drop_precision:
- /* We drop from rtime, it has more bits than stime */
- rtime >>= 1;
- total >>= 1;
- }
-
- /*
- * Make sure gcc understands that this is a 32x32->64 multiply,
- * followed by a 64/32->64 divide.
- */
- scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
- return scaled;
-}
-
-/*
* Adjust tick based cputime random precision against scheduler runtime
* accounting.
*
@@ -622,7 +578,7 @@ void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
goto update;
}
- stime = scale_stime(stime, rtime, stime + utime);
+ stime = mul_u64_u64_div_u64(stime, rtime, stime + utime);
update:
/*
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f63f337c7147..3862a28cd05d 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -54,15 +54,49 @@ static inline struct dl_bw *dl_bw_of(int i)
static inline int dl_bw_cpus(int i)
{
struct root_domain *rd = cpu_rq(i)->rd;
- int cpus = 0;
+ int cpus;
RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
"sched RCU must be held");
+
+ if (cpumask_subset(rd->span, cpu_active_mask))
+ return cpumask_weight(rd->span);
+
+ cpus = 0;
+
for_each_cpu_and(i, rd->span, cpu_active_mask)
cpus++;
return cpus;
}
+
+static inline unsigned long __dl_bw_capacity(int i)
+{
+ struct root_domain *rd = cpu_rq(i)->rd;
+ unsigned long cap = 0;
+
+ RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
+ "sched RCU must be held");
+
+ for_each_cpu_and(i, rd->span, cpu_active_mask)
+ cap += capacity_orig_of(i);
+
+ return cap;
+}
+
+/*
+ * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity
+ * of the CPU the task is running on rather rd's \Sum CPU capacity.
+ */
+static inline unsigned long dl_bw_capacity(int i)
+{
+ if (!static_branch_unlikely(&sched_asym_cpucapacity) &&
+ capacity_orig_of(i) == SCHED_CAPACITY_SCALE) {
+ return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT;
+ } else {
+ return __dl_bw_capacity(i);
+ }
+}
#else
static inline struct dl_bw *dl_bw_of(int i)
{
@@ -73,6 +107,11 @@ static inline int dl_bw_cpus(int i)
{
return 1;
}
+
+static inline unsigned long dl_bw_capacity(int i)
+{
+ return SCHED_CAPACITY_SCALE;
+}
#endif
static inline
@@ -1098,7 +1137,7 @@ void init_dl_task_timer(struct sched_dl_entity *dl_se)
* cannot use the runtime, and so it replenishes the task. This rule
* works fine for implicit deadline tasks (deadline == period), and the
* CBS was designed for implicit deadline tasks. However, a task with
- * constrained deadline (deadine < period) might be awakened after the
+ * constrained deadline (deadline < period) might be awakened after the
* deadline, but before the next period. In this case, replenishing the
* task would allow it to run for runtime / deadline. As in this case
* deadline < period, CBS enables a task to run for more than the
@@ -1604,6 +1643,7 @@ static int
select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
{
struct task_struct *curr;
+ bool select_rq;
struct rq *rq;
if (sd_flag != SD_BALANCE_WAKE)
@@ -1623,10 +1663,19 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
* other hand, if it has a shorter deadline, we
* try to make it stay here, it might be important.
*/
- if (unlikely(dl_task(curr)) &&
- (curr->nr_cpus_allowed < 2 ||
- !dl_entity_preempt(&p->dl, &curr->dl)) &&
- (p->nr_cpus_allowed > 1)) {
+ select_rq = unlikely(dl_task(curr)) &&
+ (curr->nr_cpus_allowed < 2 ||
+ !dl_entity_preempt(&p->dl, &curr->dl)) &&
+ p->nr_cpus_allowed > 1;
+
+ /*
+ * Take the capacity of the CPU into account to
+ * ensure it fits the requirement of the task.
+ */
+ if (static_branch_unlikely(&sched_asym_cpucapacity))
+ select_rq |= !dl_task_fits_capacity(p, cpu);
+
+ if (select_rq) {
int target = find_later_rq(p);
if (target != -1 &&
@@ -2430,8 +2479,8 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
}
}
-const struct sched_class dl_sched_class = {
- .next = &rt_sched_class,
+const struct sched_class dl_sched_class
+ __attribute__((section("__dl_sched_class"))) = {
.enqueue_task = enqueue_task_dl,
.dequeue_task = dequeue_task_dl,
.yield_task = yield_task_dl,
@@ -2551,11 +2600,12 @@ void sched_dl_do_global(void)
int sched_dl_overflow(struct task_struct *p, int policy,
const struct sched_attr *attr)
{
- struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
u64 period = attr->sched_period ?: attr->sched_deadline;
u64 runtime = attr->sched_runtime;
u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
- int cpus, err = -1;
+ int cpus, err = -1, cpu = task_cpu(p);
+ struct dl_bw *dl_b = dl_bw_of(cpu);
+ unsigned long cap;
if (attr->sched_flags & SCHED_FLAG_SUGOV)
return 0;
@@ -2570,15 +2620,17 @@ int sched_dl_overflow(struct task_struct *p, int policy,
* allocated bandwidth of the container.
*/
raw_spin_lock(&dl_b->lock);
- cpus = dl_bw_cpus(task_cpu(p));
+ cpus = dl_bw_cpus(cpu);
+ cap = dl_bw_capacity(cpu);
+
if (dl_policy(policy) && !task_has_dl_policy(p) &&
- !__dl_overflow(dl_b, cpus, 0, new_bw)) {
+ !__dl_overflow(dl_b, cap, 0, new_bw)) {
if (hrtimer_active(&p->dl.inactive_timer))
__dl_sub(dl_b, p->dl.dl_bw, cpus);
__dl_add(dl_b, new_bw, cpus);
err = 0;
} else if (dl_policy(policy) && task_has_dl_policy(p) &&
- !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) {
+ !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) {
/*
* XXX this is slightly incorrect: when the task
* utilization decreases, we should delay the total
@@ -2635,6 +2687,14 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
}
/*
+ * Default limits for DL period; on the top end we guard against small util
+ * tasks still getting rediculous long effective runtimes, on the bottom end we
+ * guard against timer DoS.
+ */
+unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */
+unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */
+
+/*
* This function validates the new parameters of a -deadline task.
* We ask for the deadline not being zero, and greater or equal
* than the runtime, as well as the period of being zero or
@@ -2646,6 +2706,8 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
*/
bool __checkparam_dl(const struct sched_attr *attr)
{
+ u64 period, max, min;
+
/* special dl tasks don't actually use any parameter */
if (attr->sched_flags & SCHED_FLAG_SUGOV)
return true;
@@ -2669,12 +2731,21 @@ bool __checkparam_dl(const struct sched_attr *attr)
attr->sched_period & (1ULL << 63))
return false;
+ period = attr->sched_period;
+ if (!period)
+ period = attr->sched_deadline;
+
/* runtime <= deadline <= period (if period != 0) */
- if ((attr->sched_period != 0 &&
- attr->sched_period < attr->sched_deadline) ||
+ if (period < attr->sched_deadline ||
attr->sched_deadline < attr->sched_runtime)
return false;
+ max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC;
+ min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC;
+
+ if (period < min || period > max)
+ return false;
+
return true;
}
@@ -2715,19 +2786,19 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
#ifdef CONFIG_SMP
int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed)
{
+ unsigned long flags, cap;
unsigned int dest_cpu;
struct dl_bw *dl_b;
bool overflow;
- int cpus, ret;
- unsigned long flags;
+ int ret;
dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
rcu_read_lock_sched();
dl_b = dl_bw_of(dest_cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
- cpus = dl_bw_cpus(dest_cpu);
- overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
+ cap = dl_bw_capacity(dest_cpu);
+ overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw);
if (overflow) {
ret = -EBUSY;
} else {
@@ -2737,6 +2808,8 @@ int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allo
* We will free resources in the source root_domain
* later on (see set_cpus_allowed_dl()).
*/
+ int cpus = dl_bw_cpus(dest_cpu);
+
__dl_add(dl_b, p->dl.dl_bw, cpus);
ret = 0;
}
@@ -2769,16 +2842,15 @@ int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
bool dl_cpu_busy(unsigned int cpu)
{
- unsigned long flags;
+ unsigned long flags, cap;
struct dl_bw *dl_b;
bool overflow;
- int cpus;
rcu_read_lock_sched();
dl_b = dl_bw_of(cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
- cpus = dl_bw_cpus(cpu);
- overflow = __dl_overflow(dl_b, cpus, 0, 0);
+ cap = dl_bw_capacity(cpu);
+ overflow = __dl_overflow(dl_b, cap, 0, 0);
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 04fa8dbcfa4d..2ba8f230feb9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -22,8 +22,6 @@
*/
#include "sched.h"
-#include <trace/events/sched.h>
-
/*
* Targeted preemption latency for CPU-bound tasks:
*
@@ -3094,7 +3092,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
#ifdef CONFIG_SMP
do {
- u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib;
+ u32 divider = get_pelt_divider(&se->avg);
se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
} while (0);
@@ -3440,16 +3438,18 @@ static inline void
update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
long delta = gcfs_rq->avg.util_avg - se->avg.util_avg;
- /*
- * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
- * See ___update_load_avg() for details.
- */
- u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+ u32 divider;
/* Nothing to update */
if (!delta)
return;
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
+ divider = get_pelt_divider(&cfs_rq->avg);
+
/* Set new sched_entity's utilization */
se->avg.util_avg = gcfs_rq->avg.util_avg;
se->avg.util_sum = se->avg.util_avg * divider;
@@ -3463,16 +3463,18 @@ static inline void
update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
long delta = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
- /*
- * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
- * See ___update_load_avg() for details.
- */
- u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+ u32 divider;
/* Nothing to update */
if (!delta)
return;
+ /*
+ * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+ * See ___update_load_avg() for details.
+ */
+ divider = get_pelt_divider(&cfs_rq->avg);
+
/* Set new sched_entity's runnable */
se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
se->avg.runnable_sum = se->avg.runnable_avg * divider;
@@ -3500,7 +3502,7 @@ update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
* See ___update_load_avg() for details.
*/
- divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+ divider = get_pelt_divider(&cfs_rq->avg);
if (runnable_sum >= 0) {
/*
@@ -3646,7 +3648,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
if (cfs_rq->removed.nr) {
unsigned long r;
- u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+ u32 divider = get_pelt_divider(&cfs_rq->avg);
raw_spin_lock(&cfs_rq->removed.lock);
swap(cfs_rq->removed.util_avg, removed_util);
@@ -3701,7 +3703,7 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
* cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
* See ___update_load_avg() for details.
*/
- u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
+ u32 divider = get_pelt_divider(&cfs_rq->avg);
/*
* When we attach the @se to the @cfs_rq, we must align the decay
@@ -3922,6 +3924,8 @@ static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
enqueued = cfs_rq->avg.util_est.enqueued;
enqueued += _task_util_est(p);
WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued);
+
+ trace_sched_util_est_cfs_tp(cfs_rq);
}
/*
@@ -3952,6 +3956,8 @@ util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep)
ue.enqueued -= min_t(unsigned int, ue.enqueued, _task_util_est(p));
WRITE_ONCE(cfs_rq->avg.util_est.enqueued, ue.enqueued);
+ trace_sched_util_est_cfs_tp(cfs_rq);
+
/*
* Skip update of task's estimated utilization when the task has not
* yet completed an activation, e.g. being migrated.
@@ -4017,6 +4023,8 @@ util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep)
ue.ewma >>= UTIL_EST_WEIGHT_SHIFT;
done:
WRITE_ONCE(p->se.avg.util_est, ue);
+
+ trace_sched_util_est_se_tp(&p->se);
}
static inline int task_fits_capacity(struct task_struct *p, long capacity)
@@ -5618,14 +5626,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
}
-dequeue_throttle:
- if (!se)
- sub_nr_running(rq, 1);
+ /* At this point se is NULL and we are at root level*/
+ sub_nr_running(rq, 1);
/* balance early to pull high priority tasks */
if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
rq->next_balance = jiffies;
+dequeue_throttle:
util_est_dequeue(&rq->cfs, p, task_sleep);
hrtick_update(rq);
}
@@ -7161,7 +7169,7 @@ static void yield_task_fair(struct rq *rq)
set_skip_buddy(se);
}
-static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
+static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
{
struct sched_entity *se = &p->se;
@@ -8049,7 +8057,7 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
};
}
-static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
+static unsigned long scale_rt_capacity(int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long max = arch_scale_cpu_capacity(cpu);
@@ -8081,7 +8089,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
static void update_cpu_capacity(struct sched_domain *sd, int cpu)
{
- unsigned long capacity = scale_rt_capacity(sd, cpu);
+ unsigned long capacity = scale_rt_capacity(cpu);
struct sched_group *sdg = sd->groups;
cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu);
@@ -8703,8 +8711,14 @@ static bool update_pick_idlest(struct sched_group *idlest,
case group_has_spare:
/* Select group with most idle CPUs */
- if (idlest_sgs->idle_cpus >= sgs->idle_cpus)
+ if (idlest_sgs->idle_cpus > sgs->idle_cpus)
+ return false;
+
+ /* Select group with lowest group_util */
+ if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
+ idlest_sgs->group_util <= sgs->group_util)
return false;
+
break;
}
@@ -10027,7 +10041,12 @@ static void kick_ilb(unsigned int flags)
{
int ilb_cpu;
- nohz.next_balance++;
+ /*
+ * Increase nohz.next_balance only when if full ilb is triggered but
+ * not if we only update stats.
+ */
+ if (flags & NOHZ_BALANCE_KICK)
+ nohz.next_balance = jiffies+1;
ilb_cpu = find_new_ilb();
@@ -10348,6 +10367,14 @@ static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags,
}
}
+ /*
+ * next_balance will be updated only when there is a need.
+ * When the CPU is attached to null domain for ex, it will not be
+ * updated.
+ */
+ if (likely(update_next_balance))
+ nohz.next_balance = next_balance;
+
/* Newly idle CPU doesn't need an update */
if (idle != CPU_NEWLY_IDLE) {
update_blocked_averages(this_cpu);
@@ -10368,14 +10395,6 @@ abort:
if (has_blocked_load)
WRITE_ONCE(nohz.has_blocked, 1);
- /*
- * next_balance will be updated only when there is a need.
- * When the CPU is attached to null domain for ex, it will not be
- * updated.
- */
- if (likely(update_next_balance))
- nohz.next_balance = next_balance;
-
return ret;
}
@@ -11118,8 +11137,8 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task
/*
* All the scheduling class methods:
*/
-const struct sched_class fair_sched_class = {
- .next = &idle_sched_class,
+const struct sched_class fair_sched_class
+ __attribute__((section("__fair_sched_class"))) = {
.enqueue_task = enqueue_task_fair,
.dequeue_task = dequeue_task_fair,
.yield_task = yield_task_fair,
@@ -11292,3 +11311,9 @@ const struct cpumask *sched_trace_rd_span(struct root_domain *rd)
#endif
}
EXPORT_SYMBOL_GPL(sched_trace_rd_span);
+
+int sched_trace_rq_nr_running(struct rq *rq)
+{
+ return rq ? rq->nr_running : -1;
+}
+EXPORT_SYMBOL_GPL(sched_trace_rq_nr_running);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 1ae95b9150d3..6bf34986f45c 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -453,11 +453,6 @@ prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
BUG();
}
-static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
-{
- return 0;
-}
-
static void update_curr_idle(struct rq *rq)
{
}
@@ -465,8 +460,8 @@ static void update_curr_idle(struct rq *rq)
/*
* Simple, special scheduling class for the per-CPU idle tasks:
*/
-const struct sched_class idle_sched_class = {
- /* .next is NULL */
+const struct sched_class idle_sched_class
+ __attribute__((section("__idle_sched_class"))) = {
/* no enqueue/yield_task for idle tasks */
/* dequeue is not valid, we print a debug message there: */
@@ -486,8 +481,6 @@ const struct sched_class idle_sched_class = {
.task_tick = task_tick_idle,
- .get_rr_interval = get_rr_interval_idle,
-
.prio_changed = prio_changed_idle,
.switched_to = switched_to_idle,
.update_curr = update_curr_idle,
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 808244f3ddd9..5a6ea03f9882 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -140,7 +140,8 @@ static int __init housekeeping_nohz_full_setup(char *str)
{
unsigned int flags;
- flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
+ flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
+ HK_FLAG_MISC | HK_FLAG_KTHREAD;
return housekeeping_setup(str, flags);
}
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index de22da666ac7..d2a655643a02 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -347,7 +347,7 @@ static inline void calc_global_nohz(void) { }
*
* Called from the global timer code.
*/
-void calc_global_load(unsigned long ticks)
+void calc_global_load(void)
{
unsigned long sample_window;
long active, delta;
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index b4b1ff96642f..2c613e1cff3a 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -28,8 +28,6 @@
#include "sched.h"
#include "pelt.h"
-#include <trace/events/sched.h>
-
/*
* Approximate:
* val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
@@ -83,8 +81,6 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
return c1 + c2 + c3;
}
-#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
-
/*
* Accumulate the three separate parts of the sum; d1 the remainder
* of the last (incomplete) period, d2 the span of full periods and d3
@@ -264,7 +260,7 @@ ___update_load_sum(u64 now, struct sched_avg *sa,
static __always_inline void
___update_load_avg(struct sched_avg *sa, unsigned long load)
{
- u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
+ u32 divider = get_pelt_divider(sa);
/*
* Step 2: update *_avg.
diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
index eb034d9f024d..795e43e02afc 100644
--- a/kernel/sched/pelt.h
+++ b/kernel/sched/pelt.h
@@ -37,6 +37,11 @@ update_irq_load_avg(struct rq *rq, u64 running)
}
#endif
+static inline u32 get_pelt_divider(struct sched_avg *avg)
+{
+ return LOAD_AVG_MAX - 1024 + avg->period_contrib;
+}
+
/*
* When a task is dequeued, its estimated utilization should not be update if
* its util_avg has not been updated at least once.
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 8f45cdb6463b..e53b711bd643 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -190,7 +190,6 @@ static void group_init(struct psi_group *group)
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
mutex_init(&group->avgs_lock);
/* Init trigger-related members */
- atomic_set(&group->poll_scheduled, 0);
mutex_init(&group->trigger_lock);
INIT_LIST_HEAD(&group->triggers);
memset(group->nr_triggers, 0, sizeof(group->nr_triggers));
@@ -199,7 +198,7 @@ static void group_init(struct psi_group *group)
memset(group->polling_total, 0, sizeof(group->polling_total));
group->polling_next_update = ULLONG_MAX;
group->polling_until = 0;
- rcu_assign_pointer(group->poll_kworker, NULL);
+ rcu_assign_pointer(group->poll_task, NULL);
}
void __init psi_init(void)
@@ -547,47 +546,38 @@ static u64 update_triggers(struct psi_group *group, u64 now)
return now + group->poll_min_period;
}
-/*
- * Schedule polling if it's not already scheduled. It's safe to call even from
- * hotpath because even though kthread_queue_delayed_work takes worker->lock
- * spinlock that spinlock is never contended due to poll_scheduled atomic
- * preventing such competition.
- */
+/* Schedule polling if it's not already scheduled. */
static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay)
{
- struct kthread_worker *kworker;
+ struct task_struct *task;
- /* Do not reschedule if already scheduled */
- if (atomic_cmpxchg(&group->poll_scheduled, 0, 1) != 0)
+ /*
+ * Do not reschedule if already scheduled.
+ * Possible race with a timer scheduled after this check but before
+ * mod_timer below can be tolerated because group->polling_next_update
+ * will keep updates on schedule.
+ */
+ if (timer_pending(&group->poll_timer))
return;
rcu_read_lock();
- kworker = rcu_dereference(group->poll_kworker);
+ task = rcu_dereference(group->poll_task);
/*
* kworker might be NULL in case psi_trigger_destroy races with
* psi_task_change (hotpath) which can't use locks
*/
- if (likely(kworker))
- kthread_queue_delayed_work(kworker, &group->poll_work, delay);
- else
- atomic_set(&group->poll_scheduled, 0);
+ if (likely(task))
+ mod_timer(&group->poll_timer, jiffies + delay);
rcu_read_unlock();
}
-static void psi_poll_work(struct kthread_work *work)
+static void psi_poll_work(struct psi_group *group)
{
- struct kthread_delayed_work *dwork;
- struct psi_group *group;
u32 changed_states;
u64 now;
- dwork = container_of(work, struct kthread_delayed_work, work);
- group = container_of(dwork, struct psi_group, poll_work);
-
- atomic_set(&group->poll_scheduled, 0);
-
mutex_lock(&group->trigger_lock);
now = sched_clock();
@@ -623,6 +613,35 @@ out:
mutex_unlock(&group->trigger_lock);
}
+static int psi_poll_worker(void *data)
+{
+ struct psi_group *group = (struct psi_group *)data;
+ struct sched_param param = {
+ .sched_priority = 1,
+ };
+
+ sched_setscheduler_nocheck(current, SCHED_FIFO, &param);
+
+ while (true) {
+ wait_event_interruptible(group->poll_wait,
+ atomic_cmpxchg(&group->poll_wakeup, 1, 0) ||
+ kthread_should_stop());
+ if (kthread_should_stop())
+ break;
+
+ psi_poll_work(group);
+ }
+ return 0;
+}
+
+static void poll_timer_fn(struct timer_list *t)
+{
+ struct psi_group *group = from_timer(group, t, poll_timer);
+
+ atomic_set(&group->poll_wakeup, 1);
+ wake_up_interruptible(&group->poll_wait);
+}
+
static void record_times(struct psi_group_cpu *groupc, int cpu,
bool memstall_tick)
{
@@ -1099,22 +1118,20 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
mutex_lock(&group->trigger_lock);
- if (!rcu_access_pointer(group->poll_kworker)) {
- struct sched_param param = {
- .sched_priority = 1,
- };
- struct kthread_worker *kworker;
+ if (!rcu_access_pointer(group->poll_task)) {
+ struct task_struct *task;
- kworker = kthread_create_worker(0, "psimon");
- if (IS_ERR(kworker)) {
+ task = kthread_create(psi_poll_worker, group, "psimon");
+ if (IS_ERR(task)) {
kfree(t);
mutex_unlock(&group->trigger_lock);
- return ERR_CAST(kworker);
+ return ERR_CAST(task);
}
- sched_setscheduler_nocheck(kworker->task, SCHED_FIFO, &param);
- kthread_init_delayed_work(&group->poll_work,
- psi_poll_work);
- rcu_assign_pointer(group->poll_kworker, kworker);
+ atomic_set(&group->poll_wakeup, 0);
+ init_waitqueue_head(&group->poll_wait);
+ wake_up_process(task);
+ timer_setup(&group->poll_timer, poll_timer_fn, 0);
+ rcu_assign_pointer(group->poll_task, task);
}
list_add(&t->node, &group->triggers);
@@ -1132,7 +1149,7 @@ static void psi_trigger_destroy(struct kref *ref)
{
struct psi_trigger *t = container_of(ref, struct psi_trigger, refcount);
struct psi_group *group = t->group;
- struct kthread_worker *kworker_to_destroy = NULL;
+ struct task_struct *task_to_destroy = NULL;
if (static_branch_likely(&psi_disabled))
return;
@@ -1158,13 +1175,13 @@ static void psi_trigger_destroy(struct kref *ref)
period = min(period, div_u64(tmp->win.size,
UPDATES_PER_WINDOW));
group->poll_min_period = period;
- /* Destroy poll_kworker when the last trigger is destroyed */
+ /* Destroy poll_task when the last trigger is destroyed */
if (group->poll_states == 0) {
group->polling_until = 0;
- kworker_to_destroy = rcu_dereference_protected(
- group->poll_kworker,
+ task_to_destroy = rcu_dereference_protected(
+ group->poll_task,
lockdep_is_held(&group->trigger_lock));
- rcu_assign_pointer(group->poll_kworker, NULL);
+ rcu_assign_pointer(group->poll_task, NULL);
}
}
@@ -1172,25 +1189,23 @@ static void psi_trigger_destroy(struct kref *ref)
/*
* Wait for both *trigger_ptr from psi_trigger_replace and
- * poll_kworker RCUs to complete their read-side critical sections
- * before destroying the trigger and optionally the poll_kworker
+ * poll_task RCUs to complete their read-side critical sections
+ * before destroying the trigger and optionally the poll_task
*/
synchronize_rcu();
/*
* Destroy the kworker after releasing trigger_lock to prevent a
* deadlock while waiting for psi_poll_work to acquire trigger_lock
*/
- if (kworker_to_destroy) {
+ if (task_to_destroy) {
/*
* After the RCU grace period has expired, the worker
- * can no longer be found through group->poll_kworker.
+ * can no longer be found through group->poll_task.
* But it might have been already scheduled before
* that - deschedule it cleanly before destroying it.
*/
- kthread_cancel_delayed_work_sync(&group->poll_work);
- atomic_set(&group->poll_scheduled, 0);
-
- kthread_destroy_worker(kworker_to_destroy);
+ del_timer_sync(&group->poll_timer);
+ kthread_stop(task_to_destroy);
}
kfree(t);
}
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index f395ddb75f38..f215eea6a966 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2429,8 +2429,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
return 0;
}
-const struct sched_class rt_sched_class = {
- .next = &fair_sched_class,
+const struct sched_class rt_sched_class
+ __attribute__((section("__rt_sched_class"))) = {
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,
.yield_task = yield_task_rt,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 877fb08eb1b0..3fd283892761 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -67,6 +67,7 @@
#include <linux/tsacct_kern.h>
#include <asm/tlb.h>
+#include <asm-generic/vmlinux.lds.h>
#ifdef CONFIG_PARAVIRT
# include <asm/paravirt.h>
@@ -75,6 +76,8 @@
#include "cpupri.h"
#include "cpudeadline.h"
+#include <trace/events/sched.h>
+
#ifdef CONFIG_SCHED_DEBUG
# define SCHED_WARN_ON(x) WARN_ONCE(x, #x)
#else
@@ -96,6 +99,7 @@ extern atomic_long_t calc_load_tasks;
extern void calc_global_load_tick(struct rq *this_rq);
extern long calc_load_fold_active(struct rq *this_rq, long adjust);
+extern void call_trace_sched_update_nr_running(struct rq *rq, int count);
/*
* Helpers for converting nanosecond timing to jiffy resolution
*/
@@ -310,11 +314,26 @@ void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
__dl_update(dl_b, -((s32)tsk_bw / cpus));
}
-static inline
-bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw)
+static inline bool __dl_overflow(struct dl_bw *dl_b, unsigned long cap,
+ u64 old_bw, u64 new_bw)
{
return dl_b->bw != -1 &&
- dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw;
+ cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw;
+}
+
+/*
+ * Verify the fitness of task @p to run on @cpu taking into account the
+ * CPU original capacity and the runtime/deadline ratio of the task.
+ *
+ * The function will return true if the CPU original capacity of the
+ * @cpu scaled by SCHED_CAPACITY_SCALE >= runtime/deadline ratio of the
+ * task and false otherwise.
+ */
+static inline bool dl_task_fits_capacity(struct task_struct *p, int cpu)
+{
+ unsigned long cap = arch_scale_cpu_capacity(cpu);
+
+ return cap_scale(p->dl.dl_deadline, cap) >= p->dl.dl_runtime;
}
extern void init_dl_bw(struct dl_bw *dl_b);
@@ -862,6 +881,8 @@ struct uclamp_rq {
unsigned int value;
struct uclamp_bucket bucket[UCLAMP_BUCKETS];
};
+
+DECLARE_STATIC_KEY_FALSE(sched_uclamp_used);
#endif /* CONFIG_UCLAMP_TASK */
/*
@@ -1182,6 +1203,16 @@ struct rq_flags {
#endif
};
+/*
+ * Lockdep annotation that avoids accidental unlocks; it's like a
+ * sticky/continuous lockdep_assert_held().
+ *
+ * This avoids code that has access to 'struct rq *rq' (basically everything in
+ * the scheduler) from accidentally unlocking the rq if they do not also have a
+ * copy of the (on-stack) 'struct rq_flags rf'.
+ *
+ * Also see Documentation/locking/lockdep-design.rst.
+ */
static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
{
rf->cookie = lockdep_pin_lock(&rq->lock);
@@ -1739,7 +1770,6 @@ extern const u32 sched_prio_to_wmult[40];
#define RETRY_TASK ((void *)-1UL)
struct sched_class {
- const struct sched_class *next;
#ifdef CONFIG_UCLAMP_TASK
int uclamp_enabled;
@@ -1748,7 +1778,7 @@ struct sched_class {
void (*enqueue_task) (struct rq *rq, struct task_struct *p, int flags);
void (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags);
void (*yield_task) (struct rq *rq);
- bool (*yield_to_task)(struct rq *rq, struct task_struct *p, bool preempt);
+ bool (*yield_to_task)(struct rq *rq, struct task_struct *p);
void (*check_preempt_curr)(struct rq *rq, struct task_struct *p, int flags);
@@ -1796,7 +1826,7 @@ struct sched_class {
#ifdef CONFIG_FAIR_GROUP_SCHED
void (*task_change_group)(struct task_struct *p, int type);
#endif
-};
+} __aligned(STRUCT_ALIGNMENT); /* STRUCT_ALIGN(), vmlinux.lds.h */
static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
{
@@ -1810,17 +1840,18 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next)
next->sched_class->set_next_task(rq, next, false);
}
-#ifdef CONFIG_SMP
-#define sched_class_highest (&stop_sched_class)
-#else
-#define sched_class_highest (&dl_sched_class)
-#endif
+/* Defined in include/asm-generic/vmlinux.lds.h */
+extern struct sched_class __begin_sched_classes[];
+extern struct sched_class __end_sched_classes[];
+
+#define sched_class_highest (__end_sched_classes - 1)
+#define sched_class_lowest (__begin_sched_classes - 1)
#define for_class_range(class, _from, _to) \
- for (class = (_from); class != (_to); class = class->next)
+ for (class = (_from); class != (_to); class--)
#define for_each_class(class) \
- for_class_range(class, sched_class_highest, NULL)
+ for_class_range(class, sched_class_highest, sched_class_lowest)
extern const struct sched_class stop_sched_class;
extern const struct sched_class dl_sched_class;
@@ -1930,12 +1961,7 @@ extern int __init sched_tick_offload_init(void);
*/
static inline void sched_update_tick_dependency(struct rq *rq)
{
- int cpu;
-
- if (!tick_nohz_full_enabled())
- return;
-
- cpu = cpu_of(rq);
+ int cpu = cpu_of(rq);
if (!tick_nohz_full_cpu(cpu))
return;
@@ -1955,6 +1981,9 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
unsigned prev_nr = rq->nr_running;
rq->nr_running = prev_nr + count;
+ if (trace_sched_update_nr_running_tp_enabled()) {
+ call_trace_sched_update_nr_running(rq, count);
+ }
#ifdef CONFIG_SMP
if (prev_nr < 2 && rq->nr_running >= 2) {
@@ -1969,6 +1998,10 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
static inline void sub_nr_running(struct rq *rq, unsigned count)
{
rq->nr_running -= count;
+ if (trace_sched_update_nr_running_tp_enabled()) {
+ call_trace_sched_update_nr_running(rq, count);
+ }
+
/* Check if we still need preemption */
sched_update_tick_dependency(rq);
}
@@ -2016,6 +2049,16 @@ void arch_scale_freq_tick(void)
#endif
#ifndef arch_scale_freq_capacity
+/**
+ * arch_scale_freq_capacity - get the frequency scale factor of a given CPU.
+ * @cpu: the CPU in question.
+ *
+ * Return: the frequency scale factor normalized against SCHED_CAPACITY_SCALE, i.e.
+ *
+ * f_curr
+ * ------ * SCHED_CAPACITY_SCALE
+ * f_max
+ */
static __always_inline
unsigned long arch_scale_freq_capacity(int cpu)
{
@@ -2349,12 +2392,35 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
#ifdef CONFIG_UCLAMP_TASK
unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id);
+/**
+ * uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values.
+ * @rq: The rq to clamp against. Must not be NULL.
+ * @util: The util value to clamp.
+ * @p: The task to clamp against. Can be NULL if you want to clamp
+ * against @rq only.
+ *
+ * Clamps the passed @util to the max(@rq, @p) effective uclamp values.
+ *
+ * If sched_uclamp_used static key is disabled, then just return the util
+ * without any clamping since uclamp aggregation at the rq level in the fast
+ * path is disabled, rendering this operation a NOP.
+ *
+ * Use uclamp_eff_value() if you don't care about uclamp values at rq level. It
+ * will return the correct effective uclamp value of the task even if the
+ * static key is disabled.
+ */
static __always_inline
unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
struct task_struct *p)
{
- unsigned long min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
- unsigned long max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
+ unsigned long min_util;
+ unsigned long max_util;
+
+ if (!static_branch_likely(&sched_uclamp_used))
+ return util;
+
+ min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
+ max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
if (p) {
min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
@@ -2371,6 +2437,19 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
return clamp(util, min_util, max_util);
}
+
+/*
+ * When uclamp is compiled in, the aggregation at rq level is 'turned off'
+ * by default in the fast path and only gets turned on once userspace performs
+ * an operation that requires it.
+ *
+ * Returns true if userspace opted-in to use uclamp and aggregation at rq level
+ * hence is active.
+ */
+static inline bool uclamp_is_used(void)
+{
+ return static_branch_likely(&sched_uclamp_used);
+}
#else /* CONFIG_UCLAMP_TASK */
static inline
unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
@@ -2378,6 +2457,11 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
{
return util;
}
+
+static inline bool uclamp_is_used(void)
+{
+ return false;
+}
#endif /* CONFIG_UCLAMP_TASK */
#ifdef arch_scale_freq_capacity
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
index 4c9e9975684f..394bc8126a1e 100644
--- a/kernel/sched/stop_task.c
+++ b/kernel/sched/stop_task.c
@@ -102,12 +102,6 @@ prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
BUG(); /* how!?, what priority? */
}
-static unsigned int
-get_rr_interval_stop(struct rq *rq, struct task_struct *task)
-{
- return 0;
-}
-
static void update_curr_stop(struct rq *rq)
{
}
@@ -115,8 +109,8 @@ static void update_curr_stop(struct rq *rq)
/*
* Simple, special scheduling class for the per-CPU stop tasks:
*/
-const struct sched_class stop_sched_class = {
- .next = &dl_sched_class,
+const struct sched_class stop_sched_class
+ __attribute__((section("__stop_sched_class"))) = {
.enqueue_task = enqueue_task_stop,
.dequeue_task = dequeue_task_stop,
@@ -136,8 +130,6 @@ const struct sched_class stop_sched_class = {
.task_tick = task_tick_stop,
- .get_rr_interval = get_rr_interval_stop,
-
.prio_changed = prio_changed_stop,
.switched_to = switched_to_stop,
.update_curr = update_curr_stop,
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index ba81187bb7af..9079d865a935 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1328,7 +1328,7 @@ sd_init(struct sched_domain_topology_level *tl,
sd_flags = (*tl->sd_flags)();
if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
"wrong sd_flags in topology description\n"))
- sd_flags &= ~TOPOLOGY_SD_FLAGS;
+ sd_flags &= TOPOLOGY_SD_FLAGS;
/* Apply detected topology flags */
sd_flags |= dflags;
diff --git a/kernel/smp.c b/kernel/smp.c
index aa17eedff5be..d0ae8eb6bf8b 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -634,8 +634,7 @@ static int __init nrcpus(char *str)
{
int nr_cpus;
- get_option(&str, &nr_cpus);
- if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
+ if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
nr_cpu_ids = nr_cpus;
return 0;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index db1ce7af2563..1b4d2dc270a5 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1780,6 +1780,20 @@ static struct ctl_table kern_table[] = {
.proc_handler = sched_rt_handler,
},
{
+ .procname = "sched_deadline_period_max_us",
+ .data = &sysctl_sched_dl_period_max,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "sched_deadline_period_min_us",
+ .data = &sysctl_sched_dl_period_min,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
.procname = "sched_rr_timeslice_ms",
.data = &sysctl_sched_rr_timeslice,
.maxlen = sizeof(int),
@@ -1801,6 +1815,13 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = sysctl_sched_uclamp_handler,
},
+ {
+ .procname = "sched_util_clamp_min_rt_default",
+ .data = &sysctl_sched_uclamp_util_min_rt_default,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = sysctl_sched_uclamp_handler,
+ },
#endif
#ifdef CONFIG_SCHED_AUTOGROUP
{
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index d20d489841c8..63a632f9896c 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2193,7 +2193,7 @@ EXPORT_SYMBOL(ktime_get_coarse_ts64);
void do_timer(unsigned long ticks)
{
jiffies_64 += ticks;
- calc_global_load(ticks);
+ calc_global_load();
}
/**
diff --git a/lib/cpumask.c b/lib/cpumask.c
index fb22fb266f93..85da6ab4fbb5 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -6,6 +6,7 @@
#include <linux/export.h>
#include <linux/memblock.h>
#include <linux/numa.h>
+#include <linux/sched/isolation.h>
/**
* cpumask_next - get the next cpu in a cpumask
@@ -205,22 +206,27 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask)
*/
unsigned int cpumask_local_spread(unsigned int i, int node)
{
- int cpu;
+ int cpu, hk_flags;
+ const struct cpumask *mask;
+ hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ;
+ mask = housekeeping_cpumask(hk_flags);
/* Wrap: we always want a cpu. */
- i %= num_online_cpus();
+ i %= cpumask_weight(mask);
if (node == NUMA_NO_NODE) {
- for_each_cpu(cpu, cpu_online_mask)
+ for_each_cpu(cpu, mask) {
if (i-- == 0)
return cpu;
+ }
} else {
/* NUMA first. */
- for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
+ for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
if (i-- == 0)
return cpu;
+ }
- for_each_cpu(cpu, cpu_online_mask) {
+ for_each_cpu(cpu, mask) {
/* Skip NUMA nodes, done above. */
if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
continue;
diff --git a/lib/math/div64.c b/lib/math/div64.c
index 368ca7fd0d82..3952a07130d8 100644
--- a/lib/math/div64.c
+++ b/lib/math/div64.c
@@ -190,3 +190,44 @@ u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
return __iter_div_u64_rem(dividend, divisor, remainder);
}
EXPORT_SYMBOL(iter_div_u64_rem);
+
+#ifndef mul_u64_u64_div_u64
+u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c)
+{
+ u64 res = 0, div, rem;
+ int shift;
+
+ /* can a * b overflow ? */
+ if (ilog2(a) + ilog2(b) > 62) {
+ /*
+ * (b * a) / c is equal to
+ *
+ * (b / c) * a +
+ * (b % c) * a / c
+ *
+ * if nothing overflows. Can the 1st multiplication
+ * overflow? Yes, but we do not care: this can only
+ * happen if the end result can't fit in u64 anyway.
+ *
+ * So the code below does
+ *
+ * res = (b / c) * a;
+ * b = b % c;
+ */
+ div = div64_u64_rem(b, c, &rem);
+ res = div * a;
+ b = rem;
+
+ shift = ilog2(a) + ilog2(b) - 62;
+ if (shift > 0) {
+ /* drop precision */
+ b >>= shift;
+ c >>= shift;
+ if (!c)
+ return res;
+ }
+ }
+
+ return res + div64_u64(a * b, c);
+}
+#endif
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 7bd6440c63bf..9de33b594ff2 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -11,6 +11,7 @@
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
+#include <linux/sched/isolation.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#include <net/net_namespace.h>
@@ -741,7 +742,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
{
struct rps_map *old_map, *map;
cpumask_var_t mask;
- int err, cpu, i;
+ int err, cpu, i, hk_flags;
static DEFINE_MUTEX(rps_map_mutex);
if (!capable(CAP_NET_ADMIN))
@@ -756,6 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
return err;
}
+ hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
+ cpumask_and(mask, mask, housekeeping_cpumask(hk_flags));
+ if (cpumask_empty(mask)) {
+ free_cpumask_var(mask);
+ return -EINVAL;
+ }
+
map = kzalloc(max_t(unsigned int,
RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
GFP_KERNEL);