linux-kernel - Re: [PATCH] perf vendor events: Update datasource event name to fix duplicate events

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Message-Id: <BD37AC99-0B4A-4F37-9ECB-80A79EFF30A2@linux.vnet.ibm.com>
Date:   Tue, 5 Dec 2023 12:44:05 +0530
From:   Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
To:     Ian Rogers <irogers@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        James Clark <james.clark@....com>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Disha Goel <disgoel@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf vendor events: Update datasource event name to fix
 duplicate events



> On 05-Dec-2023, at 1:42 AM, Ian Rogers <irogers@...gle.com> wrote:
> 
> On Thu, Nov 23, 2023 at 8:01 AM Athira Rajeev
> <atrajeev@...ux.vnet.ibm.com> wrote:
>> 
>> Running "perf list" on powerpc fails with segfault
>> as below:
>> 
>>   ./perf list
>>   Segmentation fault (core dumped)
>> 
>> This happens because of duplicate events in the json list.
>> The powerpc Json event list contains some event with same
>> event name, but different event code. They are:
>> - PM_INST_FROM_L3MISS (Present in datasource and frontend)
>> - PM_MRK_DATA_FROM_L2MISS (Present in datasource and marked)
>> - PM_MRK_INST_FROM_L3MISS (Present in datasource and marked)
>> - PM_MRK_DATA_FROM_L3MISS (Present in datasource and marked)
>> 
>> pmu_events_table__num_events uses the value from
>> table_pmu->num_entries which includes duplicate events as
>> well. This causes issue during "perf list" and results in
>> segmentation fault.
>> 
>> Since both event codes are valid, append _DSRC to the Data
>> Source events (datasource.json), so that they would have a
>> unique name. Also add PM_DATA_FROM_L2MISS_DSRC and
>> PM_DATA_FROM_L3MISS_DSRC events. With the fix, perf list
>> works as expected.
>> 
>> Fixes: fc1435807533 ("perf vendor events power10: Update JSON/events")
>> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
> 
> Given duplicate events creates broken pmu-events.c we should capture
> that as an exception in jevents.py. That way a JEVENTS_ARCH=all build
> will fail if any vendor/architecture would break in this way. We
> should also add JEVENTS_ARCH=all to tools/perf/tests/make. Athira, do
> you want to look at doing this?
> 
> Thanks,
> Ian

Hi Ian,

That’s a great suggestion. This will definitely help to capture the issues ahead.
I am interested and will work on adding this as part of tools/perf/tests/make

Thanks
Athira
> 
>> ---
>> .../arch/powerpc/power10/datasource.json       | 18 ++++++++++++++----
>> 1 file changed, 14 insertions(+), 4 deletions(-)
>> 
>> diff --git a/tools/perf/pmu-events/arch/powerpc/power10/datasource.json b/tools/perf/pmu-events/arch/powerpc/power10/datasource.json
>> index 6b0356f2d301..0eeaaf1a95b8 100644
>> --- a/tools/perf/pmu-events/arch/powerpc/power10/datasource.json
>> +++ b/tools/perf/pmu-events/arch/powerpc/power10/datasource.json
>> @@ -99,6 +99,11 @@
>>     "EventName": "PM_INST_FROM_L2MISS",
>>     "BriefDescription": "The processor's instruction cache was reloaded from a source beyond the local core's L2 due to a demand miss."
>>   },
>> +  {
>> +    "EventCode": "0x0003C0000000C040",
>> +    "EventName": "PM_DATA_FROM_L2MISS_DSRC",
>> +    "BriefDescription": "The processor's L1 data cache was reloaded from a source beyond the local core's L2 due to a demand miss."
>> +  },
>>   {
>>     "EventCode": "0x000380000010C040",
>>     "EventName": "PM_INST_FROM_L2MISS_ALL",
>> @@ -161,9 +166,14 @@
>>   },
>>   {
>>     "EventCode": "0x000780000000C040",
>> -    "EventName": "PM_INST_FROM_L3MISS",
>> +    "EventName": "PM_INST_FROM_L3MISS_DSRC",
>>     "BriefDescription": "The processor's instruction cache was reloaded from beyond the local core's L3 due to a demand miss."
>>   },
>> +  {
>> +    "EventCode": "0x0007C0000000C040",
>> +    "EventName": "PM_DATA_FROM_L3MISS_DSRC",
>> +    "BriefDescription": "The processor's L1 data cache was reloaded from beyond the local core's L3 due to a demand miss."
>> +  },
>>   {
>>     "EventCode": "0x000780000010C040",
>>     "EventName": "PM_INST_FROM_L3MISS_ALL",
>> @@ -981,7 +991,7 @@
>>   },
>>   {
>>     "EventCode": "0x0003C0000000C142",
>> -    "EventName": "PM_MRK_DATA_FROM_L2MISS",
>> +    "EventName": "PM_MRK_DATA_FROM_L2MISS_DSRC",
>>     "BriefDescription": "The processor's L1 data cache was reloaded from a source beyond the local core's L2 due to a demand miss for a marked instruction."
>>   },
>>   {
>> @@ -1046,12 +1056,12 @@
>>   },
>>   {
>>     "EventCode": "0x000780000000C142",
>> -    "EventName": "PM_MRK_INST_FROM_L3MISS",
>> +    "EventName": "PM_MRK_INST_FROM_L3MISS_DSRC",
>>     "BriefDescription": "The processor's instruction cache was reloaded from beyond the local core's L3 due to a demand miss for a marked instruction."
>>   },
>>   {
>>     "EventCode": "0x0007C0000000C142",
>> -    "EventName": "PM_MRK_DATA_FROM_L3MISS",
>> +    "EventName": "PM_MRK_DATA_FROM_L3MISS_DSRC",
>>     "BriefDescription": "The processor's L1 data cache was reloaded from beyond the local core's L3 due to a demand miss for a marked instruction."
>>   },
>>   {
>> --
>> 2.39.3