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authorLinus Torvalds2022-12-15 18:01:16 -0800
committerLinus Torvalds2022-12-15 18:01:16 -0800
commitfe36bb8736ee9e38fa6173e1271ed8c5cf7bc907 (patch)
tree15948d02fe68c2b8c8d6de803006a82f226853de /Documentation
parent851f657a86421dded42b6175c6ea0f4f5e86af97 (diff)
parenteb9d58947d40699d93e5e69e1ddc54e41da7e132 (diff)
Merge tag 'trace-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing updates from Steven Rostedt: - Add options to the osnoise tracer: - 'panic_on_stop' option that panics the kernel if osnoise is greater than some user defined threshold. - 'preempt' option, to test noise while preemption is disabled - 'irq' option, to test noise when interrupts are disabled - Add .percent and .graph suffix to histograms to give different outputs - Add nohitcount to disable showing hitcount in histogram output - Add new __cpumask() to trace event fields to annotate that a unsigned long array is a cpumask to user space and should be treated as one. - Add trace_trigger kernel command line parameter to enable trace event triggers at boot up. Useful to trace stack traces, disable tracing and take snapshots. - Fix x86/kmmio mmio tracer to work with the updates to lockdep - Unify the panic and die notifiers - Add back ftrace_expect reference that is used to extract more information in the ftrace_bug() code. - Have trigger filter parsing errors show up in the tracing error log. - Updated MAINTAINERS file to add kernel tracing mailing list and patchwork info - Use IDA to keep track of event type numbers. - And minor fixes and clean ups * tag 'trace-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (44 commits) tracing: Fix cpumask() example typo tracing: Improve panic/die notifiers ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels tracing: Do not synchronize freeing of trigger filter on boot up tracing: Remove pointer (asterisk) and brackets from cpumask_t field tracing: Have trigger filter parsing errors show up in error_log x86/mm/kmmio: Remove redundant preempt_disable() tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line Documentation/osnoise: Add osnoise/options documentation tracing/osnoise: Add preempt and/or irq disabled options tracing/osnoise: Add PANIC_ON_STOP option Documentation/osnoise: Escape underscore of NO_ prefix tracing: Fix some checker warnings tracing/osnoise: Make osnoise_options static tracing: remove unnecessary trace_trigger ifdef ring-buffer: Handle resize in early boot up tracing/hist: Fix issue of losting command info in error_log tracing: Fix issue of missing one synthetic field tracing/hist: Fix out-of-bound write on 'action_data.var_ref_idx' tracing/hist: Fix wrong return value in parse_action_params() ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt19
-rw-r--r--Documentation/trace/histogram.rst10
-rw-r--r--Documentation/trace/osnoise-tracer.rst32
3 files changed, 58 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb388c6c8c60..5a0eff3231c6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6266,6 +6266,25 @@
See also Documentation/trace/ftrace.rst "trace options"
section.
+ trace_trigger=[trigger-list]
+ [FTRACE] Add a event trigger on specific events.
+ Set a trigger on top of a specific event, with an optional
+ filter.
+
+ The format is is "trace_trigger=<event>.<trigger>[ if <filter>],..."
+ Where more than one trigger may be specified that are comma deliminated.
+
+ For example:
+
+ trace_trigger="sched_switch.stacktrace if prev_state == 2"
+
+ The above will enable the "stacktrace" trigger on the "sched_switch"
+ event but only trigger it if the "prev_state" of the "sched_switch"
+ event is "2" (TASK_UNINTERUPTIBLE).
+
+ See also "Event triggers" in Documentation/trace/events.rst
+
+
traceoff_on_warning
[FTRACE] enable this option to disable tracing when a
warning is hit. This turns off "tracing_on". Tracing can
diff --git a/Documentation/trace/histogram.rst b/Documentation/trace/histogram.rst
index 87bd772836c0..f95459aa984f 100644
--- a/Documentation/trace/histogram.rst
+++ b/Documentation/trace/histogram.rst
@@ -25,7 +25,7 @@ Documentation written by Tom Zanussi
hist:keys=<field1[,field2,...]>[:values=<field1[,field2,...]>]
[:sort=<field1[,field2,...]>][:size=#entries][:pause][:continue]
- [:clear][:name=histname1][:<handler>.<action>] [if <filter>]
+ [:clear][:name=histname1][:nohitcount][:<handler>.<action>] [if <filter>]
When a matching event is hit, an entry is added to a hash table
using the key(s) and value(s) named. Keys and values correspond to
@@ -79,6 +79,8 @@ Documentation written by Tom Zanussi
.log2 display log2 value rather than raw number
.buckets=size display grouping of values rather than raw number
.usecs display a common_timestamp in microseconds
+ .percent display a number of percentage value
+ .graph display a bar-graph of a value
============= =================================================
Note that in general the semantics of a given field aren't
@@ -137,6 +139,12 @@ Documentation written by Tom Zanussi
existing trigger, rather than via the '>' operator, which will cause
the trigger to be removed through truncation.
+ The 'nohitcount' (or NOHC) parameter will suppress display of
+ raw hitcount in the histogram. This option requires at least one
+ value field which is not a 'raw hitcount'. For example,
+ 'hist:...:vals=hitcount:nohitcount' is rejected, but
+ 'hist:...:vals=hitcount.percent:nohitcount' is OK.
+
- enable_hist/disable_hist
The enable_hist and disable_hist triggers can be used to have one
diff --git a/Documentation/trace/osnoise-tracer.rst b/Documentation/trace/osnoise-tracer.rst
index 963def9f97c6..140ef2533d26 100644
--- a/Documentation/trace/osnoise-tracer.rst
+++ b/Documentation/trace/osnoise-tracer.rst
@@ -92,8 +92,8 @@ Note that the example above shows a high number of HW noise samples.
The reason being is that this sample was taken on a virtual machine,
and the host interference is detected as a hardware interference.
-Tracer options
----------------------
+Tracer Configuration
+--------------------
The tracer has a set of options inside the osnoise directory, they are:
@@ -109,6 +109,27 @@ The tracer has a set of options inside the osnoise directory, they are:
- tracing_threshold: the minimum delta between two time() reads to be
considered as noise, in us. When set to 0, the default value will
be used, which is currently 5 us.
+ - osnoise/options: a set of on/off options that can be enabled by
+ writing the option name to the file or disabled by writing the option
+ name preceded with the 'NO\_' prefix. For example, writing
+ NO_OSNOISE_WORKLOAD disables the OSNOISE_WORKLOAD option. The
+ special DEAFAULTS option resets all options to the default value.
+
+Tracer Options
+--------------
+
+The osnoise/options file exposes a set of on/off configuration options for
+the osnoise tracer. These options are:
+
+ - DEFAULTS: reset the options to the default value.
+ - OSNOISE_WORKLOAD: do not dispatch osnoise workload (see dedicated
+ section below).
+ - PANIC_ON_STOP: call panic() if the tracer stops. This option serves to
+ capture a vmcore.
+ - OSNOISE_PREEMPT_DISABLE: disable preemption while running the osnoise
+ workload, allowing only IRQ and hardware-related noise.
+ - OSNOISE_IRQ_DISABLE: disable IRQs while running the osnoise workload,
+ allowing only NMIs and hardware-related noise, like hwlat tracer.
Additional Tracing
------------------
@@ -150,3 +171,10 @@ tracepoints is smaller than eight us reported in the sample_threshold.
The reason roots in the overhead of the entry and exit code that happens
before and after any interference execution. This justifies the dual
approach: measuring thread and tracing.
+
+Running osnoise tracer without workload
+---------------------------------------
+
+By enabling the osnoise tracer with the NO_OSNOISE_WORKLOAD option set,
+the osnoise: tracepoints serve to measure the execution time of
+any type of Linux task, free from the interference of other tasks.