linux-kernel - Re: [PATCH v2 3/5] perf arm-spe: Save per CPU information in metadata

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Message-ID: <4eea0c0e-e651-49cc-96ee-ef9809e80012@arm.com>
Date: Fri, 27 Sep 2024 09:16:34 +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 3/5] perf arm-spe: Save per CPU information in metadata

On 9/27/24 07:21, Namhyung Kim wrote:>
> On Sat, Sep 14, 2024 at 10:54:56PM +0100, Leo Yan wrote:
>> Save the Arm SPE information on a per-CPU basis. This approach is easier
>> in the decoding phase for retrieving metadata based on the CPU number of
>> every Arm SPE record.
>>
>> Signed-off-by: Leo Yan <leo.yan@....com>
>> ---
>>   tools/perf/arch/arm64/util/arm-spe.c | 71 +++++++++++++++++++++++++++-
>>   1 file changed, 70 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
>> index 15478989ef30..2790a37709a5 100644
>> --- a/tools/perf/arch/arm64/util/arm-spe.c
>> +++ b/tools/perf/arch/arm64/util/arm-spe.c
>> @@ -26,6 +26,8 @@
>>   #include "../../../util/arm-spe.h"
>>   #include <tools/libc_compat.h> // reallocarray
>>
>> +#define ARM_SPE_CPU_MAGIC            0x1010101010101010ULL
>> +
>>   #define KiB(x) ((x) * 1024)
>>   #define MiB(x) ((x) * 1024 * 1024)
>>
>> @@ -73,14 +75,66 @@ arm_spe_info_priv_size(struct auxtrace_record *itr __maybe_unused,
>>        return size;
>>   }
>>
>> +static int arm_spe_save_cpu_header(struct auxtrace_record *itr,
>> +                                struct perf_cpu cpu, __u64 data[])
>> +{
>> +     struct arm_spe_recording *sper =
>> +                     container_of(itr, struct arm_spe_recording, itr);
>> +     struct perf_pmu *pmu = NULL;
>> +     struct perf_pmu tmp_pmu;
>> +     char cpu_id_str[16];
>> +     char *cpuid = NULL;
>> +     u64 val;
>> +
>> +     snprintf(cpu_id_str, sizeof(cpu_id_str), "%d", cpu.cpu);
>> +     tmp_pmu.cpus = perf_cpu_map__new(cpu_id_str);
>> +     if (!tmp_pmu.cpus)
>> +             return -ENOMEM;
>> +
>> +     /* Read CPU MIDR */
>> +     cpuid = perf_pmu__getcpuid(&tmp_pmu);
>> +     if (!cpuid)
>> +             return -ENOMEM;
> 
> You'd better call perf_cpu_map__put() before return.

Will do.

Just for recording, 'cpuid' should be released at the end of function.

>> +     val = strtol(cpuid, NULL, 16);
>> +     perf_cpu_map__put(tmp_pmu.cpus);
>> +
>> +     data[ARM_SPE_MAGIC] = ARM_SPE_CPU_MAGIC;
>> +     data[ARM_SPE_CPU] = cpu.cpu;
>> +     data[ARM_SPE_CPU_NR_PARAMS] = ARM_SPE_CPU_PRIV_MAX - ARM_SPE_CPU_MIDR;
>> +     data[ARM_SPE_CPU_MIDR] = val;
>> +
>> +     /* Find the associate Arm SPE PMU for the CPU */
>> +     if (perf_cpu_map__has(sper->arm_spe_pmu->cpus, cpu))
>> +             pmu = sper->arm_spe_pmu;
>> +
>> +     if (!pmu) {
>> +             /* No Arm SPE PMU is found */
>> +             data[ARM_SPE_CPU_PMU_TYPE] = ULLONG_MAX;
>> +             data[ARM_SPE_CAP_MIN_IVAL] = 0;
>> +     } else {
>> +             data[ARM_SPE_CPU_PMU_TYPE] = pmu->type;
>> +
>> +             if (perf_pmu__scan_file(pmu, "caps/min_interval", "%lu", &val) != 1)
>> +                     val = 0;
>> +             data[ARM_SPE_CAP_MIN_IVAL] = val;
>> +     }
>> +
>> +     return ARM_SPE_CPU_PRIV_MAX;
>> +}
>> +
>>   static int arm_spe_info_fill(struct auxtrace_record *itr,
>>                             struct perf_session *session,
>>                             struct perf_record_auxtrace_info *auxtrace_info,
>>                             size_t priv_size)
>>   {
>> +     int i, ret;
>> +     size_t offset;
>>        struct arm_spe_recording *sper =
>>                        container_of(itr, struct arm_spe_recording, itr);
>>        struct perf_pmu *arm_spe_pmu = sper->arm_spe_pmu;
>> +     struct perf_cpu_map *cpu_map = arm_spe_find_cpus(session->evlist);
> 
> Maybe you can move this to later in the function to make the error
> handling easier.  Otherwise it should call perf_cpu_map__put().

Good point. Will do.

>> +     struct perf_cpu cpu;
>> +     __u64 *data;
>>
>>        if (priv_size != arm_spe_info_priv_size(itr, session->evlist))
>>                return -EINVAL;
>> @@ -89,8 +143,23 @@ static int arm_spe_info_fill(struct auxtrace_record *itr,
>>                return -EINVAL;
>>
>>        auxtrace_info->type = PERF_AUXTRACE_ARM_SPE;
>> -     auxtrace_info->priv[ARM_SPE_PMU_TYPE] = arm_spe_pmu->type;
>> +     auxtrace_info->priv[ARM_SPE_HEADER_VERSION] = ARM_SPE_HEADER_CURRENT_VERSION;
>> +     auxtrace_info->priv[ARM_SPE_HEADER_SIZE] =
>> +             ARM_SPE_AUXTRACE_PRIV_MAX - ARM_SPE_HEADER_VERSION;
>> +     auxtrace_info->priv[ARM_SPE_SHARED_PMU_TYPE] = arm_spe_pmu->type;
>> +     auxtrace_info->priv[ARM_SPE_CPUS_NUM] = perf_cpu_map__nr(cpu_map);
>> +
>> +     offset = ARM_SPE_AUXTRACE_PRIV_MAX;
>> +     perf_cpu_map__for_each_cpu(cpu, i, cpu_map) {
>> +             assert(offset < priv_size);
>> +             data = &auxtrace_info->priv[offset];
>> +             ret = arm_spe_save_cpu_header(itr, cpu, data);
>> +             if (ret < 0)
>> +                     return ret;
> 
> Please break the loop and release the cpu map.

Will do.

Thanks for good catchings!

Leo