Groups > linux.kernel > #1282079

Re: [PATCH 3/7] perf: Migrate perf to use new tick dependency mask model

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/7] perf: Migrate perf to use new tick dependency mask model
Date	2015-12-02 18:20 +0100
Message-ID	<qBjes-1JE-43@gated-at.bofh.it> (permalink)
References	(1 earlier) <qunwu-7y6-33@gated-at.bofh.it> <qyotY-21n-35@gated-at.bofh.it> <qyHwC-6ho-19@gated-at.bofh.it> <qBiim-161-3@gated-at.bofh.it> <qBj4L-1FO-39@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Dec 02, 2015 at 06:03:14PM +0100, Frederic Weisbecker wrote:
> Right, I can do either that or I can move the dependency to the CPU level
> and count nr_freq to the cpu_ctx when any ctx gets scheduled in/out. Then
> everytime we inc and nr_freq == 1, we set the dependency (all that should
> be serialized as it only happens locally).

Doing it per CPU would, as you say, add accounting crap to the context
switch path. Now given that context switches with perf enabled are
already silly expensive that might just fall away into the noise.
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Re: [PATCH 3/7] perf: Migrate perf to use new tick dependency mask  model Peter Zijlstra <peterz@infradead.org> - 2015-12-02 17:20 +0100
  Re: [PATCH 3/7] perf: Migrate perf to use new tick dependency mask  model Frederic Weisbecker <fweisbec@gmail.com> - 2015-12-02 18:10 +0100
    Re: [PATCH 3/7] perf: Migrate perf to use new tick dependency mask  model Peter Zijlstra <peterz@infradead.org> - 2015-12-02 18:20 +0100

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