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From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Ingo Molnar <mingo@kernel.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 12:26:06 +0100	[thread overview]
Message-ID: <20160125112606.GV6357@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1453716331-21029-1-git-send-email-mgorman@techsingularity.net>

On Mon, Jan 25, 2016 at 10:05:31AM +0000, Mel Gorman wrote:
> schedstats is very useful during debugging and performance tuning but it
> incurs overhead. As such, even though it can be disabled at build time,
> it is often enabled as the information is useful.  This patch adds a
> kernel command-line and sysctl tunable to enable or disable schedstats on
> demand. It is disabled by default as someone who knows they need it can
> also learn to enable it when necessary.

So the reason its often enabled in distro configs is (IIRC) that it
enables trace_sched_stat_{wait,sleep,iowait,blocked}().

I've not looked at the details of this patch, but I suspect this patch
would make these tracepoints available but non-functional unless you
poke the magic button.

  reply	other threads:[~2016-01-25 11:26 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 [this message]
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
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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