linux-kernel - Re: [PATCH v2 2/5] perf arm-spe: Calculate meta data size

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Message-ID: <fe152d28-703b-4f97-9656-b351295a506a@arm.com>
Date: Fri, 27 Sep 2024 09:07:16 +0100
From: Leo Yan <leo.yan@....com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
 James Clark <james.clark@...aro.org>, Mike Leach <mike.leach@...aro.org>,
 Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>,
 linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/5] perf arm-spe: Calculate meta data size



On 9/27/24 07:14, Namhyung Kim wrote:
> Warning: EXTERNAL SENDER, use caution when opening links or attachments.
> 
> 
> On Sat, Sep 14, 2024 at 10:54:55PM +0100, Leo Yan wrote:
>> The metadata is designed to contain a header and per CPU information.
>>
>> The arm_spe_find_cpus() function is introduced to identify how many CPUs
>> support ARM SPE. Based on the CPU number, calculates the metadata size.
>>
>> Signed-off-by: Leo Yan <leo.yan@....com>
>> ---
>>   tools/perf/arch/arm64/util/arm-spe.c | 35 +++++++++++++++++++++++++---
>>   1 file changed, 32 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
>> index c2d5c8ca4900..15478989ef30 100644
>> --- a/tools/perf/arch/arm64/util/arm-spe.c
>> +++ b/tools/perf/arch/arm64/util/arm-spe.c
>> @@ -37,11 +37,40 @@ struct arm_spe_recording {
>>        bool                    *wrapped;
>>   };
>>
>> +static struct perf_cpu_map *arm_spe_find_cpus(struct evlist *evlist)
> 
> Please add a comment that it returns a new cpu map, and caller should
> release the reference after use.

Will do.

Thanks,
Leo

>> +{
>> +     struct perf_cpu_map *event_cpus = evlist->core.user_requested_cpus;
>> +     struct perf_cpu_map *online_cpus = perf_cpu_map__new_online_cpus();
>> +     struct perf_cpu_map *intersect_cpus;
>> +
>> +     /* cpu map is not "any" CPU , we have specific CPUs to work with */
>> +     if (!perf_cpu_map__has_any_cpu(event_cpus)) {
>> +             intersect_cpus = perf_cpu_map__intersect(event_cpus, online_cpus);
>> +             perf_cpu_map__put(online_cpus);
>> +     /* Event can be "any" CPU so count all CPUs. */
>> +     } else {
>> +             intersect_cpus = online_cpus;
>> +     }
>> +
>> +     return intersect_cpus;
>> +}