From: Mel Gorman <mgorman@techsingularity.net>
To: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Matt Fleming <matt@codeblueprint.co.uk>,
Mike Galbraith <mgalbraith@suse.de>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched: Make schedstats a runtime tunable that is disabled by default
Date: Mon, 25 Jan 2016 17:07:16 +0000 [thread overview]
Message-ID: <20160125170716.GI3162@techsingularity.net> (raw)
In-Reply-To: <20160125154635.GB4031@gmail.com>
On Mon, Jan 25, 2016 at 04:46:35PM +0100, Ingo Molnar wrote:
> > Of course, it'll be our luck that tracking the data for these
> > tracepoints is the most expensive part of schedstats ...
> >
> > Ingo?
>
> IIRC it needed only a small subset of schedstats to make those tracepoints work.
>
> We already have too much overhead in the scheduler as-is - and the extra cache
> footprint does not even show on the typically cache-rich enterprise CPUs most of
> the scalability testing goes on.
>
> My minimum requirement for such runtime enablement would be to make it entirely
> static-branch patched and triggered at the call sites as well - not hidden inside
> schedstat functions.
>
As it is, it's static-branch patched but I'm struggling to see why they
cannot be hidden in the schedstat_* functions which are just preprocessor
macros. The checks could be put in the callsites but it's a lot of updates
and I don't think the end result would be very nice to read.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2016-01-25 17:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 10:05 [PATCH] sched: Make schedstats a runtime tunable that is disabled by default Mel Gorman
2016-01-25 11:26 ` Peter Zijlstra
2016-01-25 13:39 ` Mel Gorman
2016-01-25 14:59 ` Peter Zijlstra
2016-01-25 15:46 ` Ingo Molnar
2016-01-25 17:07 ` Mel Gorman [this message]
2016-01-25 18:40 ` Ingo Molnar
2016-01-25 20:11 ` Mel Gorman
2016-01-25 20:45 ` Mel Gorman
2016-01-26 8:13 ` Ingo Molnar
2016-01-25 17:05 ` Mel Gorman
2016-01-25 15:29 ` Matt Fleming
2016-01-25 16:46 ` Mel Gorman
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