linux-kernel - Re: [PATCH 6/8] perf: Account freq events per cpu

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Message-ID: <20130801140352.GE27162@twins.programming.kicks-ass.net>
Date:	Thu, 1 Aug 2013 16:03:52 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Jiri Olsa <jolsa@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 6/8] perf: Account freq events per cpu

On Thu, Aug 01, 2013 at 03:55:27PM +0200, Frederic Weisbecker wrote:
> On Thu, Aug 01, 2013 at 03:31:55PM +0200, Peter Zijlstra wrote:
> > 
> > Where the freq thing is new and shiney, but we already had the other
> > two. Of those, cgroup events must be per cpu so that should be good,
> > the branch_stack thing tests ATTACH_TASK, which should also be good, but
> > leaves me wonder wth they do for those that are attached to tasks.
> > 
> > But yes, the frequency thing is borken.
> 
> Aie, so the freq thing,  I can either account to all CPUs (inc to all
> and send an IPI to all), or when the event scheds in/out. Probably we
> should do the former to avoid sending an IPI at all context switches.

Yeah, just go with a single global state for now..
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