* [RFC PATCH] perf/core: exposing type of context-switch-out event
@ 2018-03-01 15:40 Alexey Budankov
2018-03-01 18:08 ` Andi Kleen
0 siblings, 1 reply; 5+ messages in thread
From: Alexey Budankov @ 2018-03-01 15:40 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo
Cc: Alexander Shishkin, Jiri Olsa, Namhyung Kim, Andi Kleen,
linux-kernel, Dmitri Prokhorov
Hi,
This patch prototypes exposing the type of context-switch-out event using
PERF_RECORD_MISC_EXT_RESERVED bit for PERF_RECORD_SWITCH[_CPU_WIDE] records.
Types of context-switch-out events introduced by the patch meant to be
a) preempted (task->state == TASK_RUNNING) or b) yielded == !preempted;
The changes have been manually tested on Fedora 27 with the patched kernel:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf/core
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
kernel/events/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 57898102847f..e3ca597f4e2b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7216,6 +7216,8 @@ 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 ? 0 : PERF_RECORD_MISC_EXT_RESERVED);
/* N.B. caller checks nr_switch_events != 0 */
@@ -7225,7 +7227,7 @@ 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 */
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [RFC PATCH] perf/core: exposing type of context-switch-out event
2018-03-01 15:40 [RFC PATCH] perf/core: exposing type of context-switch-out event Alexey Budankov
@ 2018-03-01 18:08 ` Andi Kleen
2018-03-01 19:19 ` Milian Wolff
0 siblings, 1 reply; 5+ messages in thread
From: Andi Kleen @ 2018-03-01 18:08 UTC (permalink / raw)
To: Alexey Budankov
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Alexander Shishkin, Jiri Olsa, Namhyung Kim, linux-kernel,
Dmitri Prokhorov
On Thu, Mar 01, 2018 at 06:40:04PM +0300, Alexey Budankov wrote:
> Hi,
>
> This patch prototypes exposing the type of context-switch-out event using
> PERF_RECORD_MISC_EXT_RESERVED bit for PERF_RECORD_SWITCH[_CPU_WIDE] records.
It would be better to define an actually named bit in perf_event.h.
It can be the same value.
Also we would need a patch for perf script / perf report -D to print this
information.
The rest looks good to me.
-Andi
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH] perf/core: exposing type of context-switch-out event
2018-03-01 18:08 ` Andi Kleen
@ 2018-03-01 19:19 ` Milian Wolff
2018-03-01 19:36 ` Andi Kleen
0 siblings, 1 reply; 5+ messages in thread
From: Milian Wolff @ 2018-03-01 19:19 UTC (permalink / raw)
To: Andi Kleen
Cc: Alexey Budankov, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Alexander Shishkin, Jiri Olsa,
Namhyung Kim, linux-kernel, Dmitri Prokhorov
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On Donnerstag, 1. März 2018 19:08:05 CET Andi Kleen wrote:
> On Thu, Mar 01, 2018 at 06:40:04PM +0300, Alexey Budankov wrote:
> > Hi,
> >
> > This patch prototypes exposing the type of context-switch-out event using
> > PERF_RECORD_MISC_EXT_RESERVED bit for PERF_RECORD_SWITCH[_CPU_WIDE]
> > records.
> It would be better to define an actually named bit in perf_event.h.
> It can be the same value.
>
> Also we would need a patch for perf script / perf report -D to print this
> information.
>
> The rest looks good to me.
Please also add documentation Documentation/perf.data-file-format.txt, but I
just noticed that not even PERF_RECORD_SWITCH is documented there...
Otherwise I also think that this would be a very nice feature addition!
--
Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt, C++ and OpenGL Experts
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH] perf/core: exposing type of context-switch-out event
2018-03-01 19:19 ` Milian Wolff
@ 2018-03-01 19:36 ` Andi Kleen
2018-03-01 20:57 ` Milian Wolff
0 siblings, 1 reply; 5+ messages in thread
From: Andi Kleen @ 2018-03-01 19:36 UTC (permalink / raw)
To: Milian Wolff
Cc: Alexey Budankov, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Alexander Shishkin, Jiri Olsa,
Namhyung Kim, linux-kernel, Dmitri Prokhorov
> Please also add documentation Documentation/perf.data-file-format.txt, but I
> just noticed that not even PERF_RECORD_SWITCH is documented there...
That file only covers fields not generated by the kernel, but this
is coming from the kernel.
Kernel records are documented in the manpage, but Vince usually updates
that on his own.
-Andi
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH] perf/core: exposing type of context-switch-out event
2018-03-01 19:36 ` Andi Kleen
@ 2018-03-01 20:57 ` Milian Wolff
0 siblings, 0 replies; 5+ messages in thread
From: Milian Wolff @ 2018-03-01 20:57 UTC (permalink / raw)
To: Andi Kleen
Cc: Alexey Budankov, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Alexander Shishkin, Jiri Olsa,
Namhyung Kim, linux-kernel, Dmitri Prokhorov
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On Donnerstag, 1. März 2018 20:36:59 CET Andi Kleen wrote:
> > Please also add documentation Documentation/perf.data-file-format.txt, but
> > I just noticed that not even PERF_RECORD_SWITCH is documented there...
>
> That file only covers fields not generated by the kernel, but this
> is coming from the kernel.
>
> Kernel records are documented in the manpage, but Vince usually updates
> that on his own.
Ah, TIL - thanks for that tip! But I still think it would be good to have a
complete documentation of the perf.data file format in one place. I guess
patches would be welcome to add more aspects of the file format there, even if
it's generated by the kernel? That helps for thirdparty tools that parse the
perf.data files (like perfparser used by QtCreator and hotspot).
Cheers
--
Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt, C++ and OpenGL Experts
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2018-03-01 15:40 [RFC PATCH] perf/core: exposing type of context-switch-out event Alexey Budankov
2018-03-01 18:08 ` Andi Kleen
2018-03-01 19:19 ` Milian Wolff
2018-03-01 19:36 ` Andi Kleen
2018-03-01 20:57 ` Milian Wolff
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