From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Matt Fleming <matt@codeblueprint.co.uk>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/2] sched/debug: fix deadlock when enabling sched events
Date: Wed, 8 Jun 2016 08:12:37 -0500 [thread overview]
Message-ID: <20160608131237.3tixvrtpqvfv5kmg@treble> (raw)
In-Reply-To: <20160608075612.GA9369@gmail.com>
On Wed, Jun 08, 2016 at 09:56:12AM +0200, Ingo Molnar wrote:
>
> * Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -789,6 +789,13 @@ static void update_curr_fair(struct rq *rq)
> > update_curr(cfs_rq_of(&rq->curr->se));
> > }
> >
> > +void trace_sched_stat_register(void)
> > +{
> > +#ifdef CONFIG_SCHEDSTATS
> > + force_schedstat_enabled();
> > +#endif
> > +}
>
> I think it would be cleaner to provide an empty force_schedstat_enabled()
> definition in sched.h, on !CONFIG_SCHEDSTATS.
Yes, agreed.
> But it might make sense to further decouple schedstats from tracing?
Looking at how we could do that:
- The sched_stat_wait tracepoint is dependent on the wait_start schedstat.
- The sched_stat_sleep tracepoint is dependent on the sleep_start
schedstat.
- The sched_stat_iowait and sched_stat_blocked tracepoints are dependent
on the block_start schedstat.
We could move those three schedstats values out of sched_statistics and
into sched_entity, and then always update them regardless of
CONFIG_SCHEDSTATS.
That would ensure these tracepoints always work. But then again it
would add a little bit of runtime overhead.
I don't have a strong opinion either way. Thoughts?
--
Josh
next prev parent reply other threads:[~2016-06-08 13:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 19:43 [PATCH 0/2] sched/debug: more schedstats fixes Josh Poimboeuf
2016-06-07 19:43 ` [PATCH 1/2] sched/debug: fix 'schedstats=enable' cmdline option Josh Poimboeuf
2016-06-08 8:06 ` Mel Gorman
2016-06-08 14:21 ` [tip:sched/core] sched/debug: Fix " tip-bot for Josh Poimboeuf
2016-06-07 19:43 ` [PATCH 2/2] sched/debug: fix deadlock when enabling sched events Josh Poimboeuf
2016-06-07 19:54 ` Peter Zijlstra
2016-06-07 21:02 ` Josh Poimboeuf
2016-06-08 8:13 ` Mel Gorman
2016-06-07 21:06 ` Josh Poimboeuf
2016-06-08 7:56 ` Ingo Molnar
2016-06-08 13:12 ` Josh Poimboeuf [this message]
2016-06-08 13:15 ` Ingo Molnar
2016-06-13 7:32 ` [PATCH v2] " Josh Poimboeuf
2016-06-14 11:35 ` [tip:sched/urgent] sched/debug: Fix " tip-bot for Josh Poimboeuf
2016-06-08 8:11 ` [PATCH 2/2] sched/debug: fix " Mel Gorman
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