diff options
| -rw-r--r-- | Documentation/accounting/psi.txt | 9 | ||||
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 18 | ||||
| -rw-r--r-- | include/linux/cgroup-defs.h | 4 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 15 | ||||
| -rw-r--r-- | include/linux/psi.h | 25 | ||||
| -rw-r--r-- | init/Kconfig | 4 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 45 | ||||
| -rw-r--r-- | kernel/sched/psi.c | 118 |
8 files changed, 228 insertions, 10 deletions
diff --git a/Documentation/accounting/psi.txt b/Documentation/accounting/psi.txt index 3753a82f1cf5..b8ca28b60215 100644 --- a/Documentation/accounting/psi.txt +++ b/Documentation/accounting/psi.txt @@ -62,3 +62,12 @@ well as medium and long term trends. The total absolute stall time is tracked and exported as well, to allow detection of latency spikes which wouldn't necessarily make a dent in the time averages, or to average trends over custom time frames. + +Cgroup2 interface +================= + +In a system with a CONFIG_CGROUP=y kernel and the cgroup2 filesystem +mounted, pressure stall information is also tracked for tasks grouped +into cgroups. Each subdirectory in the cgroupfs mountpoint contains +cpu.pressure, memory.pressure, and io.pressure files; the format is +the same as the /proc/pressure/ files. diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index caf36105a1c7..8389d6f72a77 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -966,6 +966,12 @@ All time durations are in microseconds. $PERIOD duration. "max" for $MAX indicates no limit. If only one number is written, $MAX is updated. + cpu.pressure + A read-only nested-key file which exists on non-root cgroups. + + Shows pressure stall information for CPU. See + Documentation/accounting/psi.txt for details. + Memory ------ @@ -1271,6 +1277,12 @@ PAGE_SIZE multiple when read back. higher than the limit for an extended period of time. This reduces the impact on the workload and memory management. + memory.pressure + A read-only nested-key file which exists on non-root cgroups. + + Shows pressure stall information for memory. See + Documentation/accounting/psi.txt for details. + Usage Guidelines ~~~~~~~~~~~~~~~~ @@ -1408,6 +1420,12 @@ IO Interface Files 8:16 rbps=2097152 wbps=max riops=max wiops=max + io.pressure + A read-only nested-key file which exists on non-root cgroups. + + Shows pressure stall information for IO. See + Documentation/accounting/psi.txt for details. + Writeback ~~~~~~~~~ diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 22254c1fe1c5..5e1694fe035b 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -20,6 +20,7 @@ #include <linux/u64_stats_sync.h> #include <linux/workqueue.h> #include <linux/bpf-cgroup.h> +#include <linux/psi_types.h> #ifdef CONFIG_CGROUPS @@ -436,6 +437,9 @@ struct cgroup { /* used to schedule release agent */ struct work_struct release_agent_work; + /* used to track pressure stalls */ + struct psi_group psi; + /* used to store eBPF programs */ struct cgroup_bpf bpf; diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b622d6608605..9968332cceed 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -650,6 +650,11 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp) pr_cont_kernfs_path(cgrp->kn); } +static inline struct psi_group *cgroup_psi(struct cgroup *cgrp) +{ + return &cgrp->psi; +} + static inline void cgroup_init_kthreadd(void) { /* @@ -703,6 +708,16 @@ static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp) return NULL; } +static inline struct cgroup *cgroup_parent(struct cgroup *cgrp) +{ + return NULL; +} + +static inline struct psi_group *cgroup_psi(struct cgroup *cgrp) +{ + return NULL; +} + static inline bool task_under_cgroup_hierarchy(struct task_struct *task, struct cgroup *ancestor) { diff --git a/include/linux/psi.h b/include/linux/psi.h index b0daf050de58..8e0725aac0aa 100644 --- a/include/linux/psi.h +++ b/include/linux/psi.h @@ -4,6 +4,9 @@ #include <linux/psi_types.h> #include <linux/sched.h> +struct seq_file; +struct css_set; + #ifdef CONFIG_PSI extern bool psi_disabled; @@ -16,6 +19,14 @@ void psi_memstall_tick(struct task_struct *task, int cpu); void psi_memstall_enter(unsigned long *flags); void psi_memstall_leave(unsigned long *flags); +int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res); + +#ifdef CONFIG_CGROUPS +int psi_cgroup_alloc(struct cgroup *cgrp); +void psi_cgroup_free(struct cgroup *cgrp); +void cgroup_move_task(struct task_struct *p, struct css_set *to); +#endif + #else /* CONFIG_PSI */ static inline void psi_init(void) {} @@ -23,6 +34,20 @@ static inline void psi_init(void) {} static inline void psi_memstall_enter(unsigned long *flags) {} static inline void psi_memstall_leave(unsigned long *flags) {} +#ifdef CONFIG_CGROUPS +static inline int psi_cgroup_alloc(struct cgroup *cgrp) +{ + return 0; +} +static inline void psi_cgroup_free(struct cgroup *cgrp) +{ +} +static inline void cgroup_move_task(struct task_struct *p, struct css_set *to) +{ + rcu_assign_pointer(p->cgroups, to); +} +#endif + #endif /* CONFIG_PSI */ #endif /* _LINUX_PSI_H */ diff --git a/init/Kconfig b/init/Kconfig index 26e639df5517..a4112e95724a 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -501,6 +501,10 @@ config PSI the share of walltime in which some or all tasks in the system are delayed due to contention of the respective resource. + In kernels with cgroup support, cgroups (cgroup2 only) will + have cpu.pressure, memory.pressure, and io.pressure files, + which aggregate pressure stalls for the grouped tasks only. + For more details see Documentation/accounting/psi.txt. Say N if unsure. diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 4c1cf0969a80..8b79318810ad 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -55,6 +55,7 @@ #include <linux/nsproxy.h> #include <linux/file.h> #include <linux/sched/cputime.h> +#include <linux/psi.h> #include <net/sock.h> #define CREATE_TRACE_POINTS @@ -862,7 +863,7 @@ static void css_set_move_task(struct task_struct *task, */ WARN_ON_ONCE(task->flags & PF_EXITING); - rcu_assign_pointer(task->cgroups, to_cset); + cgroup_move_task(task, to_cset); list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : &to_cset->tasks); } @@ -3446,6 +3447,21 @@ static int cpu_stat_show(struct seq_file *seq, void *v) return ret; } +#ifdef CONFIG_PSI +static int cgroup_io_pressure_show(struct seq_file *seq, void *v) +{ + return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_IO); +} +static int cgroup_memory_pressure_show(struct seq_file *seq, void *v) +{ + return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_MEM); +} +static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v) +{ + return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_CPU); +} +#endif + static int cgroup_file_open(struct kernfs_open_file *of) { struct cftype *cft = of->kn->priv; @@ -4576,6 +4592,23 @@ static struct cftype cgroup_base_files[] = { .flags = CFTYPE_NOT_ON_ROOT, .seq_show = cpu_stat_show, }, +#ifdef CONFIG_PSI + { + .name = "io.pressure", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cgroup_io_pressure_show, + }, + { + .name = "memory.pressure", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cgroup_memory_pressure_show, + }, + { + .name = "cpu.pressure", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = cgroup_cpu_pressure_show, + }, +#endif { } /* terminate */ }; @@ -4636,6 +4669,7 @@ static void css_free_rwork_fn(struct work_struct *work) */ cgroup_put(cgroup_parent(cgrp)); kernfs_put(cgrp->kn); + psi_cgroup_free(cgrp); if (cgroup_on_dfl(cgrp)) cgroup_rstat_exit(cgrp); kfree(cgrp); @@ -4892,10 +4926,15 @@ static struct cgroup *cgroup_create(struct cgroup *parent) cgrp->self.parent = &parent->self; cgrp->root = root; cgrp->level = level; - ret = cgroup_bpf_inherit(cgrp); + + ret = psi_cgroup_alloc(cgrp); if (ret) goto out_idr_free; + ret = cgroup_bpf_inherit(cgrp); + if (ret) + goto out_psi_free; + for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) { cgrp->ancestor_ids[tcgrp->level] = tcgrp->id; @@ -4933,6 +4972,8 @@ static struct cgroup *cgroup_create(struct cgroup *parent) return cgrp; +out_psi_free: + psi_cgroup_free(cgrp); out_idr_free: cgroup_idr_remove(&root->cgroup_idr, cgrp->id); out_stat_exit: diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 595414599b98..7cdecfc010af 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -473,9 +473,35 @@ static void psi_group_change(struct psi_group *group, int cpu, schedule_delayed_work(&group->clock_work, PSI_FREQ); } +static struct psi_group *iterate_groups(struct task_struct *task, void **iter) +{ +#ifdef CONFIG_CGROUPS + struct cgroup *cgroup = NULL; + + if (!*iter) + cgroup = task->cgroups->dfl_cgrp; + else if (*iter == &psi_system) + return NULL; + else + cgroup = cgroup_parent(*iter); + + if (cgroup && cgroup_parent(cgroup)) { + *iter = cgroup; + return cgroup_psi(cgroup); + } +#else + if (*iter) + return NULL; +#endif + *iter = &psi_system; + return &psi_system; +} + void psi_task_change(struct task_struct *task, int clear, int set) { int cpu = task_cpu(task); + struct psi_group *group; + void *iter = NULL; if (!task->pid) return; @@ -492,17 +518,23 @@ void psi_task_change(struct task_struct *task, int clear, int set) task->psi_flags &= ~clear; task->psi_flags |= set; - psi_group_change(&psi_system, cpu, clear, set); + while ((group = iterate_groups(task, &iter))) + psi_group_change(group, cpu, clear, set); } void psi_memstall_tick(struct task_struct *task, int cpu) { - struct psi_group_cpu *groupc; + struct psi_group *group; + void *iter = NULL; - groupc = per_cpu_ptr(psi_system.pcpu, cpu); - write_seqcount_begin(&groupc->seq); - record_times(groupc, cpu, true); - write_seqcount_end(&groupc->seq); + while ((group = iterate_groups(task, &iter))) { + struct psi_group_cpu *groupc; + + groupc = per_cpu_ptr(group->pcpu, cpu); + write_seqcount_begin(&groupc->seq); + record_times(groupc, cpu, true); + write_seqcount_end(&groupc->seq); + } } /** @@ -565,8 +597,78 @@ void psi_memstall_leave(unsigned long *flags) rq_unlock_irq(rq, &rf); } -static int psi_show(struct seq_file *m, struct psi_group *group, - enum psi_res res) +#ifdef CONFIG_CGROUPS +int psi_cgroup_alloc(struct cgroup *cgroup) +{ + if (psi_disabled) + return 0; + + cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu); + if (!cgroup->psi.pcpu) + return -ENOMEM; + group_init(&cgroup->psi); + return 0; +} + +void psi_cgroup_free(struct cgroup *cgroup) +{ + if (psi_disabled) + return; + + cancel_delayed_work_sync(&cgroup->psi.clock_work); + free_percpu(cgroup->psi.pcpu); +} + +/** + * cgroup_move_task - move task to a different cgroup + * @task: the task + * @to: the target css_set + * + * Move task to a new cgroup and safely migrate its associated stall + * state between the different groups. + * + * This function acquires the task's rq lock to lock out concurrent + * changes to the task's scheduling state and - in case the task is + * running - concurrent changes to its stall state. + */ +void cgroup_move_task(struct task_struct *task, struct css_set *to) +{ + bool move_psi = !psi_disabled; + unsigned int task_flags = 0; + struct rq_flags rf; + struct rq *rq; + + if (move_psi) { + rq = task_rq_lock(task, &rf); + + if (task_on_rq_queued(task)) + task_flags = TSK_RUNNING; + else if (task->in_iowait) + task_flags = TSK_IOWAIT; + + if (task->flags & PF_MEMSTALL) + task_flags |= TSK_MEMSTALL; + + if (task_flags) + psi_task_change(task, task_flags, 0); + } + + /* + * Lame to do this here, but the scheduler cannot be locked + * from the outside, so we move cgroups from inside sched/. + */ + rcu_assign_pointer(task->cgroups, to); + + if (move_psi) { + if (task_flags) + psi_task_change(task, 0, task_flags); + + task_rq_unlock(rq, task, &rf); + } +} +#endif /* CONFIG_CGROUPS */ + +int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res) { int full; |