Commit 101592b4 authored by Alexey Budankov's avatar Alexey Budankov Committed by Arnaldo Carvalho de Melo
Browse files

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



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: default avatarAlexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Tested-by: default avatarArnaldo 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e2f73a18

include/uapi/linux/perf_event.h

+15 −3
Original line number Diff line number Diff line
@@ -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)

/*

 * 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

 */

kernel/events/core.c

+4 −0
Original line number Diff line number Diff line
@@ -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);

tools/include/uapi/linux/perf_event.h

+15 −3
Original line number Diff line number Diff line
@@ -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)

/*

 * 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

 */

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