Re: [PATCH] perf, powerpc: Fix power_pmu_event_init to not useevent->ctx

[Peter Zijlstra]

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?


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