linux-kernel - Re: [PATCH V2 2/3] x86, perf: Add a separate Arch Perfmon v4 PMI handler

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Message-ID: <79e026f0-dabc-ba29-2a90-a6b24521b525@linux.intel.com>
Date:   Thu, 27 Sep 2018 09:53:28 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org, eranian@...gle.com,
        ak@...ux.intel.com, alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH V2 2/3] x86, perf: Add a separate Arch Perfmon v4 PMI
 handler



On 9/27/2018 8:51 AM, Peter Zijlstra wrote:
> On Wed, Aug 08, 2018 at 12:12:07AM -0700, kan.liang@...ux.intel.com wrote:
>> @@ -4325,6 +4428,8 @@ __init int intel_pmu_init(void)
>>   		x86_pmu.extra_regs = intel_skl_extra_regs;
>>   		x86_pmu.pebs_aliases = intel_pebs_aliases_skl;
>>   		x86_pmu.pebs_prec_dist = true;
>> +		x86_pmu.counter_freezing = disable_counter_freezing ?
>> +					   false : true;
>>   		/* all extra regs are per-cpu when HT is on */
>>   		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
>>   		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
> 
> 
> How about so instead? It is very much tied to the perfmon version, not
> the FMS.
>

Yes, it matches the name of the handler.
But the change as below is not sufficient. We have to temporarily 
disable counter_freezing in this patch for small core.
The 3/3 patch will also be impact.

I will send V3 patch for these changes.

Thanks,
Kan

> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -4049,6 +4049,9 @@ __init int intel_pmu_init(void)
>   			max((int)edx.split.num_counters_fixed, assume);
>   	}
>   
> +	if (version >= 4)
> +		x86_pmu.counter_freezing = !disable_counter_freezing;
> +
>   	if (boot_cpu_has(X86_FEATURE_PDCM)) {
>   		u64 capabilities;
>   
> @@ -4428,8 +4431,6 @@ __init int intel_pmu_init(void)
>   		x86_pmu.extra_regs = intel_skl_extra_regs;
>   		x86_pmu.pebs_aliases = intel_pebs_aliases_skl;
>   		x86_pmu.pebs_prec_dist = true;
> -		x86_pmu.counter_freezing = disable_counter_freezing ?
> -					   false : true;
>   		/* all extra regs are per-cpu when HT is on */
>   		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
>   		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
>