Re: [PATCH V6 3/6] perf, x86: large PEBS interrupt threshold

From: Peter Zijlstra
Date: Wed Apr 15 2015 - 14:41:32 EST


On Wed, Apr 15, 2015 at 06:35:48PM +0000, Liang, Kan wrote:
>
> >
> > On Thu, Apr 09, 2015 at 12:37:43PM -0400, Kan Liang wrote:
> > > @@ -280,8 +280,9 @@ static int alloc_pebs_buffer(int cpu)
> > > ds->pebs_absolute_maximum = ds->pebs_buffer_base +
> > > max * x86_pmu.pebs_record_size;
> > >
> > > - ds->pebs_interrupt_threshold = ds->pebs_buffer_base +
> > > - thresh * x86_pmu.pebs_record_size;
> > > + if (x86_pmu.intel_cap.pebs_format < 1)
> > > + ds->pebs_interrupt_threshold = ds->pebs_buffer_base +
> > > + x86_pmu.pebs_record_size;
> > >
> > > return 0;
> > > }
> >
> > I can't seem to figure out what this is about.. help?
>
> We move AUTO_RELOAD and large PEBS check to intel_pmu_hw_config.
> But for earlier platform, it calls x86_pmu_hw_config.
> So we force single PEBS record for old platform.

We're talking about intel_pmu vs core_pmu right? I don't think core_pmu
supports PEBS at all.
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