Re: [PATCH v5 2/8] perf tool: Parse pmu caps sysfs only once

From: Ravi Bangoria <ravi.bangoria@amd.com>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: acme@kernel.org, jolsa@kernel.org, irogers@google.com,
	peterz@infradead.org, rrichter@amd.com, mingo@redhat.com,
	mark.rutland@arm.com, namhyung@kernel.org, tglx@linutronix.de,
	bp@alien8.de, james.clark@arm.com, leo.yan@linaro.org,
	ak@linux.intel.com, eranian@google.com, like.xu.linux@gmail.com,
	x86@kernel.org, linux-perf-users@vger.kernel.org,
	linux-kernel@vger.kernel.org, sandipan.das@amd.com,
	ananth.narayan@amd.com, kim.phillips@amd.com,
	santosh.shukla@amd.com, Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [PATCH v5 2/8] perf tool: Parse pmu caps sysfs only once
Date: Wed, 1 Jun 2022 19:21:58 +0530	[thread overview]
Message-ID: <0c795f97-c582-8059-fcf8-82b43239f0d1@amd.com> (raw)
In-Reply-To: <47584a6b-20b9-9a3d-3125-d9fe848cea54@linux.intel.com>

Hi Kan,

[...]

>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>> index 541889fa9f9c..4b45fd8da5a3 100644
>> --- a/tools/perf/util/pmu.h
>> +++ b/tools/perf/util/pmu.h
>> @@ -46,6 +46,8 @@ struct perf_pmu {
>>       struct perf_cpu_map *cpus;
>>       struct list_head format;  /* HEAD struct perf_pmu_format -> list */
>>       struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
>> +    bool caps_initialized;
>> +    u32 nr_caps;
> 
> If they are just used for the cache purpose, I don't think we need to add the variables in the struct perf_pmu.
> 
> A static variable should be good enough. See sysctl__nmi_watchdog_enabled().

These fields are per pmu. Static variable won't help :) And they are
used in subsequent patches as well.

Thanks,
Ravi