Re: [PATCH v9] perf stat: Fix wrong skipping for per-die aggregation

[Jiri Olsa]

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@xxxxxxxxx>
> Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>

thanks,
jirka