linux-kernel - Re: [PATCH] perf parse: Fix event parser error for hybrid systems

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Date:   Sat, 12 Mar 2022 10:54:57 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     zhengjun.xing@...ux.intel.com
Cc:     peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...el.com, jolsa@...hat.com,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        irogers@...gle.com, adrian.hunter@...el.com, ak@...ux.intel.com,
        kan.liang@...ux.intel.com
Subject: Re: [PATCH] perf parse: Fix event parser error for hybrid systems

Em Mon, Mar 07, 2022 at 11:16:27PM +0800, zhengjun.xing@...ux.intel.com escreveu:
> From: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
> 
> This bug happened on hybrid systems when both cpu_core and cpu_atom
> have the same event name such as "UOPS_RETIRED.MS" while their event
> terms are different, then during perf stat, the event for cpu_atom
> will parse fail and then no output for cpu_atom.
> 
> UOPS_RETIRED.MS -> cpu_core/period=0x1e8483,umask=0x4,event=0xc2,frontend=0x8/
> UOPS_RETIRED.MS -> cpu_atom/period=0x1e8483,umask=0x1,event=0xc2/
> 
> It is because event terms in the "head" of parse_events_multi_pmu_add
> will be changed to event terms for cpu_core after parsing UOPS_RETIRED.MS
> for cpu_core, then when parsing the same event for cpu_atom, it still
> uses the event terms for cpu_core, but event terms for cpu_atom are
> different with cpu_core, the event parses for cpu_atom will fail. This
> patch fixes it, the event terms should be parsed from the original
> event.
> 
> This patch can work for the hybrid systems that have the same event
> in more than 2 PMUs. It also can work in non-hybrid systems.
> 
> Before:
> 
>  #perf stat -v  -e  UOPS_RETIRED.MS  -a sleep 1
> 
> Using CPUID GenuineIntel-6-97-1
> UOPS_RETIRED.MS -> cpu_core/period=0x1e8483,umask=0x4,event=0xc2,frontend=0x8/
> Control descriptor is not initialized
> UOPS_RETIRED.MS: 2737845 16068518485 16068518485
> 
>  Performance counter stats for 'system wide':
> 
>          2,737,845      cpu_core/UOPS_RETIRED.MS/
> 
>        1.002553850 seconds time elapsed
> 
> After:
> 
>  #perf stat -v  -e  UOPS_RETIRED.MS  -a sleep 1
> 
> Using CPUID GenuineIntel-6-97-1
> UOPS_RETIRED.MS -> cpu_core/period=0x1e8483,umask=0x4,event=0xc2,frontend=0x8/
> UOPS_RETIRED.MS -> cpu_atom/period=0x1e8483,umask=0x1,event=0xc2/
> Control descriptor is not initialized
> UOPS_RETIRED.MS: 1977555 16076950711 16076950711
> UOPS_RETIRED.MS: 568684 8038694234 8038694234

Thanks, applied.

- Arnaldo