Subject: Re: [PATCH v4 01/48] libperf: Add comments to perf_cpu_map.
To:     Ian Rogers <irogers@google.com>, Andi Kleen <ak@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        John Garry <john.garry@huawei.com>,
        "Paul A . Clarke" <pc@us.ibm.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Riccardo Mancini <rickyman7@gmail.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        Vineet Singh <vineet.singh@intel.com>,
        James Clark <james.clark@arm.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mike Leach <mike.leach@linaro.org>,
        Leo Yan <leo.yan@linaro.org>, coresight@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org, zhengjun.xing@intel.com
Cc:     eranian@google.com
References: <20220105061351.120843-1-irogers@google.com>
 <20220105061351.120843-2-irogers@google.com>
From:   kajoljain <kjain@linux.ibm.com>
Message-ID: <7344589b-1e17-ea8f-2d31-2905331fdcb3@linux.ibm.com>
Date:   Wed, 12 Jan 2022 11:05:51 +0530
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On 1/5/22 11:43 AM, Ian Rogers wrote:
> A particular observed problem is confusing the index with the CPU value,
> documentation should hopefully reduce this type of problem.
> 

Patch looks good.

Reviewed-by: Kajol Jain<kjain@linux.ibm.com>

> Reviewed-by: James Clark <james.clark@arm.com>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/lib/perf/include/internal/cpumap.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/lib/perf/include/internal/cpumap.h b/tools/lib/perf/include/internal/cpumap.h
> index 840d4032587b..4054169c12c5 100644
> --- a/tools/lib/perf/include/internal/cpumap.h
> +++ b/tools/lib/perf/include/internal/cpumap.h
> @@ -4,9 +4,18 @@
>  
>  #include <linux/refcount.h>
>  
> +/**
> + * A sized, reference counted, sorted array of integers representing CPU
> + * numbers. This is commonly used to capture which CPUs a PMU is associated
> + * with. The indices into the cpumap are frequently used as they avoid having
> + * gaps if CPU numbers were used. For events associated with a pid, rather than
> + * a CPU, a single dummy map with an entry of -1 is used.
> + */
>  struct perf_cpu_map {
>  	refcount_t	refcnt;
> +	/** Length of the map array. */
>  	int		nr;
> +	/** The CPU values. */
>  	int		map[];
>  };
>  
>