linux-kernel - Re: [PATCH] perf tools: fix failed to use cpu list for uncore events

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Message-ID: <Yg+Yn16Xyzqc2kRr@kernel.org>
Date:   Fri, 18 Feb 2022 10:01:19 -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 tools: fix failed to use cpu list for uncore events

Em Fri, Feb 18, 2022 at 05:31:27PM +0800, zhengjun.xing@...ux.intel.com escreveu:
> From: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
> 
> The 'perf record' and 'perf stat' commands have supported the option
> '-C/--cpus' to count or collect only on the list of CPUs provided.
> commit 1d3351e631fc ("perf tools: Enable on a list of CPUs for hybrid")
> add it to be supported for hybrid. For hybrid support, it checks the
> cpu list are available on hybrid PMU. But when we test only uncore
> events(or events not in cpu_core and cpu_atom), there is a bug:
> 
> Before:
>  # perf stat -C0  -e uncore_clock/clockticks/ sleep 1
>    failed to use cpu list 0
> 
> In this case, for uncore event, its pmu_name is not cpu_core or cpu_atom,
> so in evlist__fix_hybrid_cpus, perf_pmu__find_hybrid_pmu should return
> NULL,both events_nr and unmatched_count should be 0 ,then the cpu list
> check function evlist__fix_hybrid_cpus return -1 and the error "failed
> to use cpu list 0" will happen. Bypass "events_nr=0" case then the issue
> is fixed.

Thanks, applied.

- Arnaldo