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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Clark Williams <williams@redhat.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Alexey Budankov <alexey.budankov@linux.intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>, Jiri Olsa <jolsa@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 02/17] perf/core: Store context switch out type in PERF_RECORD_SWITCH[_CPU_WIDE]
Date: Fri, 20 Apr 2018 11:32:12 -0300	[thread overview]
Message-ID: <20180420143227.16030-3-acme@kernel.org> (raw)
In-Reply-To: <20180420143227.16030-1-acme@kernel.org>

From: Alexey Budankov <alexey.budankov@linux.intel.com>

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>
---
 include/uapi/linux/perf_event.h       | 18 +++++++++++++++---
 kernel/events/core.c                  |  4 ++++
 tools/include/uapi/linux/perf_event.h | 18 +++++++++++++++---
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 912b85b52344..b8e288a1f740 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -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
  */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2d5fe26551f8..1bae80aaabfb 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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);
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 912b85b52344..b8e288a1f740 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -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
  */
-- 
2.14.3

  reply	other threads:[~2018-04-20 14:33 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20 14:32 [GIT PULL 00/17] perf/urgent fixes and improvements Arnaldo Carvalho de Melo
2018-04-20 14:32 ` Arnaldo Carvalho de Melo [this message]
2018-04-20 14:32 ` [PATCH 03/17] perf report: Extend raw dump (-D) out with switch out event type Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 04/17] perf script: Extend misc field decoding " Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 05/17] perf list: Add s390 support for detailed/verbose PMU event description Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 06/17] perf: Return proper values for user stack errors Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 07/17] perf: Fix sample_max_stack maximum check Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 08/17] perf: Remove superfluous allocation error check Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 09/17] perf trace: Support MAP_FIXED_NOREPLACE Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 10/17] perf mem: Allow all record/report options Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 11/17] perf hists browser: Clarify top/report browser help Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 12/17] perf record: Remove misleading error suggestion Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 13/17] perf record: Remove suggestion to enable APIC Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 14/17] perf tools: Add '\n' at the end of parse-options error messages Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 15/17] perf tests mmap: Show which tracepoint is failing Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 16/17] perf test BPF: Fixup BPF test using epoll_pwait syscall function probe Arnaldo Carvalho de Melo
2018-04-20 14:32 ` [PATCH 17/17] coresight: Move to SPDX identifier Arnaldo Carvalho de Melo
2018-04-21  7:39 ` [GIT PULL 00/17] perf/urgent fixes and improvements Ingo Molnar

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