All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH 0/3] tracing/perf: perf_trace_buf/perf_xxx hacks.
@ 2013-06-18 19:21 Oleg Nesterov
  2013-06-18 19:22 ` [PATCH 1/3] tracing/perf: expand TRACE_EVENT(sched_stat_runtime) Oleg Nesterov
                   ` (4 more replies)
  0 siblings, 5 replies; 21+ messages in thread
From: Oleg Nesterov @ 2013-06-18 19:21 UTC (permalink / raw)
  To: Steven Rostedt, Peter Zijlstra
  Cc: Frederic Weisbecker, Ingo Molnar, Masami Hiramatsu,
	Srikar Dronamraju, zhangwei(Jovi),
	linux-kernel

Hello.

On top of "PATCH 0/3] tracing: more list_empty(perf_events) checks"
series I sent yesterday.

Compile tested only, not for inclusion yet.

But I'll appreciate if you can take a look. I'll try to test this
tomorrow somehow and let you know. Right now I am looking at asm code,
looks correct...

I also compiled the kernel with the additional patch below, everything
compiles except sched/core.o as expected.

Oleg.

--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -664,6 +664,8 @@ perf_trace_##call(void *__data, proto)					\
 									\
 	__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
 									\
+	BUILD_BUG_ON(!(__builtin_constant_p(!__task) && !__task));	\
+									\
 	head = this_cpu_ptr(event_call->perf_events);			\
 	if (__builtin_constant_p(!__task) && !__task &&			\
 				hlist_empty(head))			\


^ permalink raw reply	[flat|nested] 21+ messages in thread
* [PATCH RESEND 0/3] Teach perf_trace_##call() to check hlist_empty(perf_events)
@ 2013-07-18 18:30 Oleg Nesterov
  2013-07-18 18:30 ` [PATCH 3/3] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Oleg Nesterov
  0 siblings, 1 reply; 21+ messages in thread
From: Oleg Nesterov @ 2013-07-18 18:30 UTC (permalink / raw)
  To: Frederic Weisbecker, Peter Zijlstra, Steven Rostedt
  Cc: David Ahern, Ingo Molnar, Masami Hiramatsu, zhangwei(Jovi), linux-kernel

Hello.

The patches are the same, I only tried to update the changelogs a bit.
I am also quoting my old email below, to explain what this hack tries
to do.

	Say, "perf record -e sched:sched_switch -p1".

	Every task except /sbin/init will do perf_trace_sched_switch() and
	perf_trace_buf_prepare() + perf_trace_buf_submit for no reason(),
	it doesn't have a counter.

	So it makes sense to add the fast-path check at the start of
	perf_trace_##call(),

		if (hlist_empty(event_call->perf_events))
			return;

	The problem is, we should not do this if __task != NULL (iow, if
	DECLARE_EVENT_CLASS() uses __perf_task()), perf_tp_event() has the
	additional code for this case.

	So we should do

		if (!__task && hlist_empty(event_call->perf_events))
			return;

	But __task is changed by "{ assign; }" block right before
	perf_trace_buf_submit(). Too late for the fast-path check,
	we already called perf_trace_buf_prepare/fetch_regs.

	So. After 2/3 __perf_task() (and __perf_count/addr) is called
	when ftrace_get_offsets_##call(args) evaluates the arguments,
	and we can check !__task && hlist_empty() right after that.

Oleg.


^ permalink raw reply	[flat|nested] 21+ messages in thread
* [PATCH 0/3] Teach perf_trace_##call() to check hlist_empty(perf_events)
@ 2013-08-05 16:50 Oleg Nesterov
  2013-08-05 16:51 ` [PATCH 3/3] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Oleg Nesterov
  0 siblings, 1 reply; 21+ messages in thread
From: Oleg Nesterov @ 2013-08-05 16:50 UTC (permalink / raw)
  To: Ingo Molnar
  Cc: Steven Rostedt, Frederic Weisbecker, Peter Zijlstra, David Ahern,
	Masami Hiramatsu, zhangwei(Jovi),
	linux-kernel

Sorry for double post, forgot to cc lkml...

On 07/19, Ingo Molnar wrote:
>
> * Oleg Nesterov <oleg@redhat.com> wrote:
>
> > Hello.
> >
> > The patches are the same, I only tried to update the changelogs a bit.
> > I am also quoting my old email below, to explain what this hack tries
> > to do.
> >
> > 	Say, "perf record -e sched:sched_switch -p1".
> >
> > 	Every task except /sbin/init will do perf_trace_sched_switch() and
> > 	perf_trace_buf_prepare() + perf_trace_buf_submit for no reason(),
> > 	it doesn't have a counter.
> >
> > 	So it makes sense to add the fast-path check at the start of
> > 	perf_trace_##call(),
> >
> > 		if (hlist_empty(event_call->perf_events))
> > 			return;
> >
> > 	The problem is, we should not do this if __task != NULL (iow, if
> > 	DECLARE_EVENT_CLASS() uses __perf_task()), perf_tp_event() has the
> > 	additional code for this case.
> >
> > 	So we should do
> >
> > 		if (!__task && hlist_empty(event_call->perf_events))
> > 			return;
> >
> > 	But __task is changed by "{ assign; }" block right before
> > 	perf_trace_buf_submit(). Too late for the fast-path check,
> > 	we already called perf_trace_buf_prepare/fetch_regs.
> >
> > 	So. After 2/3 __perf_task() (and __perf_count/addr) is called
> > 	when ftrace_get_offsets_##call(args) evaluates the arguments,
> > 	and we can check !__task && hlist_empty() right after that.
> >
> > Oleg.
>
> Nice improvement.
>
> Peter, Steve, any objections?

Ingo,

It seems that everybody agree with this hack but it was forgotten,
let me resend it again.

The only change is that I added the following tags:

	Tested-by: David Ahern <dsahern@gmail.com>
	Reviewed-and-Acked-by: Steven Rostedt <rostedt@goodmis.org>

Oleg.

 include/trace/events/sched.h |   22 ++++++++--------------
 include/trace/ftrace.h       |   33 ++++++++++++++++++++-------------
 2 files changed, 28 insertions(+), 27 deletions(-)


^ permalink raw reply	[flat|nested] 21+ messages in thread
end of thread, other threads:[~2013-08-05 16:56 UTC | newest]

Thread overview: 21+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-06-18 19:21 [PATCH 0/3] tracing/perf: perf_trace_buf/perf_xxx hacks Oleg Nesterov
2013-06-18 19:22 ` [PATCH 1/3] tracing/perf: expand TRACE_EVENT(sched_stat_runtime) Oleg Nesterov
2013-06-18 19:22 ` [PATCH 2/3] tracing/perf: reimplement TP_perf_assign() logic Oleg Nesterov
2013-06-18 19:22 ` [PATCH 3/3] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Oleg Nesterov
2013-06-18 20:02   ` Steven Rostedt
2013-06-19 18:12     ` Oleg Nesterov
2013-06-19 18:24       ` Steven Rostedt
2013-06-19 12:10 ` [PATCH 0/3] tracing/perf: perf_trace_buf/perf_xxx hacks Peter Zijlstra
2013-06-19 15:28   ` Oleg Nesterov
2013-06-19 17:51     ` Oleg Nesterov
2013-06-19 18:50       ` David Ahern
2013-06-19 19:58         ` Oleg Nesterov
2013-06-20 18:23           ` Steven Rostedt
2013-06-20 18:35             ` David Ahern
2013-06-20 18:47               ` Steven Rostedt
2013-06-20 18:53                 ` David Ahern
2013-06-20 18:53                 ` Steven Rostedt
2013-06-20 22:20                   ` Steven Rostedt
2013-07-18  3:06 ` Steven Rostedt
2013-07-18 18:30 [PATCH RESEND 0/3] Teach perf_trace_##call() to check hlist_empty(perf_events) Oleg Nesterov
2013-07-18 18:30 ` [PATCH 3/3] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Oleg Nesterov
2013-08-05 16:50 [PATCH 0/3] Teach perf_trace_##call() to check hlist_empty(perf_events) Oleg Nesterov
2013-08-05 16:51 ` [PATCH 3/3] tracing/perf: Avoid perf_trace_buf_*() in perf_trace_##call() when possible Oleg Nesterov

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.