linux-kernel - Re: [PATCH V2 08/25] perf/x86: Hybrid PMU support for hardware cache event

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Message-ID: <b29200cd-88c3-a0c9-d563-d76e819fe5f7@linux.intel.com>
Date:   Thu, 11 Mar 2021 10:09:55 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org, acme@...nel.org,
        tglx@...utronix.de, bp@...en8.de, namhyung@...nel.org,
        jolsa@...hat.com, ak@...ux.intel.com, yao.jin@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, adrian.hunter@...el.com
Subject: Re: [PATCH V2 08/25] perf/x86: Hybrid PMU support for hardware cache
 event



On 3/11/2021 6:07 AM, Peter Zijlstra wrote:
> On Wed, Mar 10, 2021 at 08:37:44AM -0800, kan.liang@...ux.intel.com wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> The hardware cache events are different among hybrid PMUs. Each hybrid
>> PMU should have its own hw cache event table.
>>
>> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
>> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>>   arch/x86/events/core.c       | 11 +++++++++--
>>   arch/x86/events/perf_event.h |  9 +++++++++
>>   2 files changed, 18 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
>> index 039a851..1db4a67 100644
>> --- a/arch/x86/events/core.c
>> +++ b/arch/x86/events/core.c
>> @@ -352,6 +352,7 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>>   {
>>   	struct perf_event_attr *attr = &event->attr;
>>   	unsigned int cache_type, cache_op, cache_result;
>> +	struct x86_hybrid_pmu *pmu = is_hybrid() ? hybrid_pmu(event->pmu) : NULL;
>>   	u64 config, val;
>>   
>>   	config = attr->config;
>> @@ -371,7 +372,10 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>>   		return -EINVAL;
>>   	cache_result = array_index_nospec(cache_result, PERF_COUNT_HW_CACHE_RESULT_MAX);
>>   
>> -	val = hw_cache_event_ids[cache_type][cache_op][cache_result];
>> +	if (pmu)
>> +		val = pmu->hw_cache_event_ids[cache_type][cache_op][cache_result];
>> +	else
>> +		val = hw_cache_event_ids[cache_type][cache_op][cache_result];
>>   
>>   	if (val == 0)
>>   		return -ENOENT;
>> @@ -380,7 +384,10 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>>   		return -EINVAL;
>>   
>>   	hwc->config |= val;
>> -	attr->config1 = hw_cache_extra_regs[cache_type][cache_op][cache_result];
>> +	if (pmu)
>> +		attr->config1 = pmu->hw_cache_extra_regs[cache_type][cache_op][cache_result];
>> +	else
>> +		attr->config1 = hw_cache_extra_regs[cache_type][cache_op][cache_result];
> 
> Why not:
> 
> 	attr->config1 = hybrid(event->pmu, hw_cache_extra_regs)[cache_type][cache_op][cache_result];
> 
> ?

Because hw_cache_extra_regs is not part of the struct x86_pmu.


Thanks,
Kan