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perf/core: Store context switch out type in PERF_RECORD_SWITCH[_CPU_WIDE]

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Store preempting context switch out event into Perf trace as a part of
PERF_RECORD_SWITCH[_CPU_WIDE] record.

Percentage of preempting and non-preempting context switches help
understanding the nature of workloads (CPU or IO bound) that are running
on a machine;

The event is treated as preemption one when task->state value of the
thread being switched out is TASK_RUNNING. Event type encoding is
implemented using PERF_RECORD_MISC_SWITCH_OUT_PREEMPT bit;

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/9ff84e83-a0ca-dd82-a6d0-cb951689be74@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Alexey Budankov 2018-04-09 10:25:32 +03:00 committed by Arnaldo Carvalho de Melo
parent e2f73a1828
commit 101592b490
3 changed files with 34 additions and 6 deletions
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18
include/uapi/linux/perf_event.h
View File

@ -650,11 +650,23 @@ struct perf_event_mmap_page {
#define PERF_RECORD_MISC_COMM_EXEC (1 << 13)
#define PERF_RECORD_MISC_SWITCH_OUT (1 << 13)
/*
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
* perf_event_attr::precise_ip.
* These PERF_RECORD_MISC_* flags below are safely reused
* for the following events:
*
* PERF_RECORD_MISC_EXACT_IP - PERF_RECORD_SAMPLE of precise events
* PERF_RECORD_MISC_SWITCH_OUT_PREEMPT - PERF_RECORD_SWITCH* events
*
*
* PERF_RECORD_MISC_EXACT_IP:
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
* perf_event_attr::precise_ip.
*
* PERF_RECORD_MISC_SWITCH_OUT_PREEMPT:
* Indicates that thread was preempted in TASK_RUNNING state.
*/
#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
#define PERF_RECORD_MISC_SWITCH_OUT_PREEMPT (1 << 14)
/*
* Reserve the last bit to indicate some extended misc field
*/

4
kernel/events/core.c
View File

@ -7587,6 +7587,10 @@ static void perf_event_switch(struct task_struct *task,
},
};
if (!sched_in && task->state == TASK_RUNNING)
switch_event.event_id.header.misc |=
PERF_RECORD_MISC_SWITCH_OUT_PREEMPT;
perf_iterate_sb(perf_event_switch_output,
&switch_event,
NULL);

18
tools/include/uapi/linux/perf_event.h
View File

@ -650,11 +650,23 @@ struct perf_event_mmap_page {
#define PERF_RECORD_MISC_COMM_EXEC (1 << 13)
#define PERF_RECORD_MISC_SWITCH_OUT (1 << 13)
/*
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
* perf_event_attr::precise_ip.
* These PERF_RECORD_MISC_* flags below are safely reused
* for the following events:
*
* PERF_RECORD_MISC_EXACT_IP - PERF_RECORD_SAMPLE of precise events
* PERF_RECORD_MISC_SWITCH_OUT_PREEMPT - PERF_RECORD_SWITCH* events
*
*
* PERF_RECORD_MISC_EXACT_IP:
* Indicates that the content of PERF_SAMPLE_IP points to
* the actual instruction that triggered the event. See also
* perf_event_attr::precise_ip.
*
* PERF_RECORD_MISC_SWITCH_OUT_PREEMPT:
* Indicates that thread was preempted in TASK_RUNNING state.
*/
#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
#define PERF_RECORD_MISC_SWITCH_OUT_PREEMPT (1 << 14)
/*
* Reserve the last bit to indicate some extended misc field
*/