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 12:29:06 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
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 9/10/2021 12:04 PM, Peter Zijlstra wrote:
> 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?
> 

Yes, for !hybrid, the patch is good.

Since PEBS via PT is temporarily disabled for hybrid for now, the patch 
set should not bring any issues with hybrid either.
The hybrid PT can be fixed separately.

Thanks,
Kan