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Subject[PATCH v3 1/3] perf/core: store context switch out type into Perf trace
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Store thread context-switch-out event type into Perf trace as a part of
PERF_RECORD_SWITCH[_CPU_WIDE] records.

Introduced types of switch-out events assumed to be
a) preempt: task->state == TASK_RUNNING and b) !preempt;

New !preempt event type is encoded using new
PERF_RECORD_MISC_SWITCH_OUT_PREEMPT bit extending
existing PERF_RECORD_MISC_SWITCH_OUT bit of switch out event:

misc &= PERF_RECORD_MISC_SWITCH_OUT | PERF_RECORD_MISC_SWITCH_OUT_PREEMPT

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
include/uapi/linux/perf_event.h | 4 ++++
kernel/events/core.c | 4 +++-
tools/include/uapi/linux/perf_event.h | 4 ++++
3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 912b85b52344..cd6ad7e13824 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -655,6 +655,10 @@ struct perf_event_mmap_page {
* perf_event_attr::precise_ip.
*/
#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
+/*
+ * Indicates that thread was preempted in TASK_RUNNING state
+ */
+#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 74a6e8f12a3c..0d39192215bc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7556,6 +7556,8 @@ static void perf_event_switch(struct task_struct *task,
struct task_struct *next_prev, bool sched_in)
{
struct perf_switch_event switch_event;
+ __u16 switch_type = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT |
+ (task->state == TASK_RUNNING ? PERF_RECORD_MISC_SWITCH_OUT_PREEMPT : 0);

/* N.B. caller checks nr_switch_events != 0 */

@@ -7565,7 +7567,7 @@ static void perf_event_switch(struct task_struct *task,
.event_id = {
.header = {
/* .type */
- .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT,
+ .misc = switch_type,
/* .size */
},
/* .next_prev_pid */
diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 912b85b52344..cd6ad7e13824 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -655,6 +655,10 @@ struct perf_event_mmap_page {
* perf_event_attr::precise_ip.
*/
#define PERF_RECORD_MISC_EXACT_IP (1 << 14)
+/*
+ * Indicates that thread was preempted in TASK_RUNNING state
+ */
+#define PERF_RECORD_MISC_SWITCH_OUT_PREEMPT (1 << 14)
/*
* Reserve the last bit to indicate some extended misc field
*/
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