linux-kernel - Re: [PATCH V3 1/3] perf/x86: Add new event for AUX output counter index

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Date:   Fri, 10 Sep 2021 18:04:09 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>, Leo Yan <leo.yan@...aro.org>,
        x86@...nel.org, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 1/3] perf/x86: Add new event for AUX output counter
 index

On Tue, Sep 07, 2021 at 01:45:22PM -0400, Liang, Kan wrote:
> On 9/7/2021 12:39 PM, Adrian Hunter wrote:

> > @@ -4494,8 +4500,16 @@ static int intel_pmu_check_period(struct perf_event *event, u64 value)
> >   	return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0;
> >   }
> > +static void intel_aux_output_init(void)
> > +{
> > +	/* Refer also intel_pmu_aux_output_match() */
> > +	if (x86_pmu.intel_cap.pebs_output_pt_available)
> > +		x86_pmu.assign = intel_pmu_assign_event;
> > +}
> 
> For a hybrid machine, x86_pmu.intel_cap.pebs_output_pt_available is always
> cleared. We probably need the PMU specific
> pmu->intel_cap.pebs_output_pt_available here.
> 
> > +
> >   static int intel_pmu_aux_output_match(struct perf_event *event)
> >   {
> > +	/* intel_pmu_assign_event() is needed, refer intel_aux_output_init() */
> >   	if (!x86_pmu.intel_cap.pebs_output_pt_available)
> >   		return 0;
> > 
> 
> For a hybrid machine, this always return 0. I think we need to fix it first?

AFAICT the patch is correct for !hybrid, and the hybrid PT muck can then
also fix this up, right?