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Re: [PATCH] sched: Make schedstats a runtime tunable that is disabled by default

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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.

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[PATCH] sched: Make schedstats a runtime tunable that is disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 11:10 +0100
  Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Peter Zijlstra <peterz@infradead.org> - 2016-01-25 12:30 +0100
    Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 14:50 +0100
      Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Peter Zijlstra <peterz@infradead.org> - 2016-01-25 16:00 +0100
        Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Ingo Molnar <mingo@kernel.org> - 2016-01-25 16:50 +0100
          Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 18:10 +0100
            Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Ingo Molnar <mingo@kernel.org> - 2016-01-25 19:50 +0100
              Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 21:20 +0100
                Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 21:50 +0100
                Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Ingo Molnar <mingo@kernel.org> - 2016-01-26 09:20 +0100
        Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 18:10 +0100
  Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-25 16:30 +0100
    Re: [PATCH] sched: Make schedstats a runtime tunable that is  disabled by default Mel Gorman <mgorman@techsingularity.net> - 2016-01-25 17:50 +0100

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