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SubjectRe: [PATCH v9] perf stat: Fix wrong skipping for per-die aggregation
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Hi Arnaldo,

On 2/1/2021 6:27 AM, Jiri Olsa wrote:
> On Thu, Jan 28, 2021 at 09:34:17AM +0800, Jin Yao wrote:
>> Uncore becomes die-scope on Xeon Cascade Lake-AP and perf has supported
>> --per-die aggregation yet.
>>
>> One issue is found in check_per_pkg() for uncore events running on
>> AP system. On cascade Lake-AP, we have:
>>
>> S0-D0
>> S0-D1
>> S1-D0
>> S1-D1
>>
>> But in check_per_pkg(), S0-D1 and S1-D1 are skipped because the
>> mask bits for S0 and S1 have been set for S0-D0 and S1-D0. It doesn't
>> check die_id. So the counting for S0-D1 and S1-D1 are set to zero.
>> That's not correct.
>>
>> root@lkp-csl-2ap4 ~# ./perf stat -a -I 1000 -e llc_misses.mem_read --per-die -- sleep 5
>> 1.001460963 S0-D0 1 1317376 Bytes llc_misses.mem_read
>> 1.001460963 S0-D1 1 998016 Bytes llc_misses.mem_read
>> 1.001460963 S1-D0 1 970496 Bytes llc_misses.mem_read
>> 1.001460963 S1-D1 1 1291264 Bytes llc_misses.mem_read
>> 2.003488021 S0-D0 1 1082048 Bytes llc_misses.mem_read
>> 2.003488021 S0-D1 1 1919040 Bytes llc_misses.mem_read
>> 2.003488021 S1-D0 1 890752 Bytes llc_misses.mem_read
>> 2.003488021 S1-D1 1 2380800 Bytes llc_misses.mem_read
>> 3.005613270 S0-D0 1 1126080 Bytes llc_misses.mem_read
>> 3.005613270 S0-D1 1 2898176 Bytes llc_misses.mem_read
>> 3.005613270 S1-D0 1 870912 Bytes llc_misses.mem_read
>> 3.005613270 S1-D1 1 3388608 Bytes llc_misses.mem_read
>> 4.007627598 S0-D0 1 1124608 Bytes llc_misses.mem_read
>> 4.007627598 S0-D1 1 3884416 Bytes llc_misses.mem_read
>> 4.007627598 S1-D0 1 921088 Bytes llc_misses.mem_read
>> 4.007627598 S1-D1 1 4451840 Bytes llc_misses.mem_read
>> 5.001479927 S0-D0 1 963328 Bytes llc_misses.mem_read
>> 5.001479927 S0-D1 1 4831936 Bytes llc_misses.mem_read
>> 5.001479927 S1-D0 1 895104 Bytes llc_misses.mem_read
>> 5.001479927 S1-D1 1 5496640 Bytes llc_misses.mem_read
>>
>> From above output, we can see S0-D1 and S1-D1 don't report the interval
>> values, they are continued to grow. That's because check_per_pkg() wrongly
>> decides to use zero counts for S0-D1 and S1-D1.
>>
>> So in check_per_pkg(), we should use hashmap(socket,die) to decide if
>> the cpu counts needs to skip. Only considering socket is not enough.
>>
>> Now with this patch,
>>
>> root@lkp-csl-2ap4 ~# ./perf stat -a -I 1000 -e llc_misses.mem_read --per-die -- sleep 5
>> 1.001586691 S0-D0 1 1229440 Bytes llc_misses.mem_read
>> 1.001586691 S0-D1 1 976832 Bytes llc_misses.mem_read
>> 1.001586691 S1-D0 1 938304 Bytes llc_misses.mem_read
>> 1.001586691 S1-D1 1 1227328 Bytes llc_misses.mem_read
>> 2.003776312 S0-D0 1 1586752 Bytes llc_misses.mem_read
>> 2.003776312 S0-D1 1 875392 Bytes llc_misses.mem_read
>> 2.003776312 S1-D0 1 855616 Bytes llc_misses.mem_read
>> 2.003776312 S1-D1 1 949376 Bytes llc_misses.mem_read
>> 3.006512788 S0-D0 1 1338880 Bytes llc_misses.mem_read
>> 3.006512788 S0-D1 1 920064 Bytes llc_misses.mem_read
>> 3.006512788 S1-D0 1 877184 Bytes llc_misses.mem_read
>> 3.006512788 S1-D1 1 1020736 Bytes llc_misses.mem_read
>> 4.008895291 S0-D0 1 926592 Bytes llc_misses.mem_read
>> 4.008895291 S0-D1 1 906368 Bytes llc_misses.mem_read
>> 4.008895291 S1-D0 1 892224 Bytes llc_misses.mem_read
>> 4.008895291 S1-D1 1 987712 Bytes llc_misses.mem_read
>> 5.001590993 S0-D0 1 962624 Bytes llc_misses.mem_read
>> 5.001590993 S0-D1 1 912512 Bytes llc_misses.mem_read
>> 5.001590993 S1-D0 1 891200 Bytes llc_misses.mem_read
>> 5.001590993 S1-D1 1 978432 Bytes llc_misses.mem_read
>>
>> On no-die system, die_id is 0, actually it's hashmap(socket,0), original behavior
>> is not changed.
>>
>> Reported-by: Huang Ying <ying.huang@intel.com>
>> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
>> ---
>> v9:
>> Rename zero_per_pkg to evsel__zero_per_pkg and move it to evsel.c. Then
>> evsel__zero_per_pkg can be called under different code path.
>>
>> Call evsel__zero_per_pkg in evsel__exit().
>
> Acked-by: Jiri Olsa <jolsa@redhat.com>
>
> thanks,
> jirka
>

Can this fix be accepted or anything else I need to improve?

Thanks
Jin Yao

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