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Date: Mon, 2 Aug 2021 11:15:41 +0800
From: "Jin, Yao" <yao.jin@...ux.intel.com>
To: Riccardo Mancini <rickyman7@...il.com>
Cc: acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
mingo@...hat.com, alexander.shishkin@...ux.intel.com,
Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
ak@...ux.intel.com, kan.liang@...el.com
Subject: Re: [PATCH v3 1/2] perf pmu: Add PMU alias support
Hi Riccardo,
On 7/30/2021 4:28 PM, Riccardo Mancini wrote:
> Hi,
>
> thanks for your quick revision.
>
> There is still one small memory issue with a variable not being freed, which I
> noticed when running this patchset together with John's patchset.
>
> On Fri, 2021-07-30 at 15:07 +0800, Jin Yao wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> A perf uncore PMU may have two PMU names, a real name and an alias. The
>> alias is exported at /sys/bus/event_source/devices/uncore_*/alias.
>> The perf tool should support the alias as well.
>>
>> Add alias_name in the struct perf_pmu to store the alias. For the PMU
>> which doesn't have an alias. It's NULL.
>>
>> Introduce two X86 specific functions to retrieve the real name and the
>> alias separately.
>>
>> Only go through the sysfs to retrieve the mapping between the real name
>> and the alias once. The result is cached in a list, uncore_pmu_list.
>>
>> Nothing changed for the other ARCHs.
>>
>> With the patch, the perf tool can monitor the PMU with either the real
>> name or the alias.
>>
>> Use the real name,
>> $ perf stat -e uncore_cha_2/event=1/ -x,
>> 4044879584,,uncore_cha_2/event=1/,2528059205,100.00,,
>>
>> Use the alias,
>> $ perf stat -e uncore_type_0_2/event=1/ -x,
>> 3659675336,,uncore_type_0_2/event=1/,2287306455,100.00,,
>>
>> Co-developed-by: Jin Yao <yao.jin@...ux.intel.com>
>> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
>> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>> v3:
>> - Use fgets to read alias string from sysfs.
>> - Resource cleanup.
>>
>> v2:
>> - No change.
>>
>> tools/perf/arch/x86/util/pmu.c | 129 ++++++++++++++++++++++++++++++++-
>> tools/perf/util/parse-events.y | 3 +-
>> tools/perf/util/pmu.c | 26 ++++++-
>> tools/perf/util/pmu.h | 5 ++
>> 4 files changed, 158 insertions(+), 5 deletions(-)
>>
> <SNIP>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index 44b90d638ad5..cc9af7942e7b 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -944,13 +944,28 @@ static int pmu_max_precise(const char *name)
>> return max_precise;
>> }
>>
>> -static struct perf_pmu *pmu_lookup(const char *name)
>> +char * __weak
>> +pmu_find_real_name(const char *name)
>> +{
>> + return strdup(name);
>> +}
>> +
>> +char * __weak
>> +pmu_find_alias_name(const char *name __maybe_unused)
>> +{
>> + return NULL;
>> +}
>> +
>> +static struct perf_pmu *pmu_lookup(const char *lookup_name)
>> {
>> struct perf_pmu *pmu;
>> + char *name;
>> LIST_HEAD(format);
>> LIST_HEAD(aliases);
>> __u32 type;
>>
>> + name = pmu_find_real_name(lookup_name);
>
> name is not freed if one of the following checks fails.
>
> /*
> * The pmu data we store & need consists of the pmu
> * type value and format definitions. Load both right
> * now.
> */
> if (pmu_format(name, &format))
> return NULL;
>
> /*
> * Check the type first to avoid unnecessary work.
> */
> if (pmu_type(name, &type))
> return NULL;
>
> if (pmu_aliases(name, &aliases))
> return NULL;
>
> Thanks,
> Riccardo
>
Thanks so much for pointing this out. I also find I need to rebase the patch because it has some
conflicts with John's patch. I will prepare v4 (which will be based on tmp.perf/urgent).
Thanks
Jin Yao
>
>> @@ -973,7 +988,8 @@ static struct perf_pmu *pmu_lookup(const char *name)
>> return NULL;
>>
>> pmu->cpus = pmu_cpumask(name);
>> - pmu->name = strdup(name);
>> + pmu->name = name;
>> + pmu->alias_name = pmu_find_alias_name(name);
>> pmu->type = type;
>> pmu->is_uncore = pmu_is_uncore(name);
>> if (pmu->is_uncore)
>> @@ -1003,7 +1019,8 @@ static struct perf_pmu *pmu_find(const char *name)
>> struct perf_pmu *pmu;
>>
>> list_for_each_entry(pmu, &pmus, list)
>> - if (!strcmp(pmu->name, name))
>> + if (!strcmp(pmu->name, name) ||
>> + (pmu->alias_name && !strcmp(pmu->alias_name, name)))
>> return pmu;
>>
>> return NULL;
>> @@ -1898,6 +1915,9 @@ bool perf_pmu__has_hybrid(void)
>>
>> int perf_pmu__match(char *pattern, char *name, char *tok)
>> {
>> + if (!name)
>> + return -1;
>> +
>> if (fnmatch(pattern, name, 0))
>> return -1;
>>
>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>> index 926da483a141..f6ca9f6a06ef 100644
>> --- a/tools/perf/util/pmu.h
>> +++ b/tools/perf/util/pmu.h
>> @@ -21,6 +21,7 @@ enum {
>> #define PERF_PMU_FORMAT_BITS 64
>> #define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
>> #define CPUS_TEMPLATE_CPU "%s/bus/event_source/devices/%s/cpus"
>> +#define MAX_PMU_NAME_LEN 128
>>
>> struct perf_event_attr;
>>
>> @@ -32,6 +33,7 @@ struct perf_pmu_caps {
>>
>> struct perf_pmu {
>> char *name;
>> + char *alias_name; /* PMU alias name */
>> char *id;
>> __u32 type;
>> bool selectable;
>> @@ -135,4 +137,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu,
>> __u64 config,
>> bool perf_pmu__has_hybrid(void);
>> int perf_pmu__match(char *pattern, char *name, char *tok);
>>
>> +char *pmu_find_real_name(const char *name);
>> +char *pmu_find_alias_name(const char *name);
>> +
>> #endif /* __PMU_H */
>
>
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