linux-kernel - Re: [PATCH 1/2] perf/x86/intel: Support adaptive PEBS for fixed counters

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Date:   Wed, 10 Apr 2019 09:57:50 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
        acme@...nel.org, jolsa@...nel.org, eranian@...gle.com,
        alexander.shishkin@...ux.intel.com, ak@...ux.intel.com
Subject: Re: [PATCH 1/2] perf/x86/intel: Support adaptive PEBS for fixed
 counters



On 4/10/2019 3:41 AM, Peter Zijlstra wrote:
> On Tue, Apr 09, 2019 at 06:09:59PM -0700, kan.liang@...ux.intel.com wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> Fixed counters can also generate adaptive PEBS record, if the
>> corresponding bit in IA32_FIXED_CTR_CTRL is set.
>> Otherwise, only basic record is generated.
>>
>> Unconditionally set the bit when PEBS is enabled on fixed counters.
>> Let MSR_PEBS_CFG decide which format of PEBS record should be generated.
>> There is no harmful to leave the bit set.
> 
> I'll merge this back into:
> 
>    Subject: perf/x86/intel: Support adaptive PEBSv4
> 
> such that this bug never existed, ok?

Yes, please.

Thanks,
Kan

> 
>>
>> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>>   arch/x86/events/intel/core.c      | 5 +++++
>>   arch/x86/include/asm/perf_event.h | 1 +
>>   2 files changed, 6 insertions(+)
>>
>> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
>> index 56df0f6..f34d92b 100644
>> --- a/arch/x86/events/intel/core.c
>> +++ b/arch/x86/events/intel/core.c
>> @@ -2174,6 +2174,11 @@ static void intel_pmu_enable_fixed(struct perf_event *event)
>>   	bits <<= (idx * 4);
>>   	mask = 0xfULL << (idx * 4);
>>   
>> +	if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip) {
>> +		bits |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
>> +		mask |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
>> +	}
>> +
>>   	rdmsrl(hwc->config_base, ctrl_val);
>>   	ctrl_val &= ~mask;
>>   	ctrl_val |= bits;
>> diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
>> index dcb8bac..ce0dc88 100644
>> --- a/arch/x86/include/asm/perf_event.h
>> +++ b/arch/x86/include/asm/perf_event.h
>> @@ -33,6 +33,7 @@
>>   #define HSW_IN_TX					(1ULL << 32)
>>   #define HSW_IN_TX_CHECKPOINTED				(1ULL << 33)
>>   #define ICL_EVENTSEL_ADAPTIVE				(1ULL << 34)
>> +#define ICL_FIXED_0_ADAPTIVE				(1ULL << 32)
>>   
>>   #define AMD64_EVENTSEL_INT_CORE_ENABLE			(1ULL << 36)
>>   #define AMD64_EVENTSEL_GUESTONLY			(1ULL << 40)
>> -- 
>> 2.7.4
>>