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From: Peter Zijlstra <peterz@infradead.org>
To: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	linux-kernel@vger.kernel.org,
	Alexey Kardashevskiy <aik@au1.ibm.com>,
	Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] perf, powerpc: Fix power_pmu_event_init to not use event->ctx
Date: Tue, 19 Oct 2010 13:50:30 +0200	[thread overview]
Message-ID: <1287489030.1994.8.camel@twins> (raw)
In-Reply-To: <1287476932.29097.1617.camel@twins>

On Tue, 2010-10-19 at 10:28 +0200, Peter Zijlstra wrote:
 
> > (The reason it needs to know whether it is a per-task event is because
> > there are some hardware events on Power systems which only count when
> > the processor is not idle, and there are some fixed-function counters
> > which count such events.  For example, the "run cycles" event counts
> > cycles when the processor is not idle.  If the user asks to count
> > cycles, we can use "run cycles" if this is a per-task event, since the
> > processor is running when the task is running, by definition.  We
> > can't use "run cycles" if the user asks for "cycles" on a system-wide
> > counter.)

Right, so the problem comes from you using run-cycles as cycles? How
does that interact with things like cpu_relax() will that generate a
difference in run-cycles vs cycles?



  reply	other threads:[~2010-10-19 11:50 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-19  5:55 [PATCH] perf, powerpc: Fix power_pmu_event_init to not use event->ctx Paul Mackerras
2010-10-19  8:28 ` Peter Zijlstra
2010-10-19 11:50   ` Peter Zijlstra [this message]
2010-10-19 21:56     ` Paul Mackerras
2010-10-19 10:48 ` [tip:perf/core] " tip-bot for Paul Mackerras

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