[PATCH v4 01/48] libperf: Add comments to perf_cpu_map.

[kajoljain]

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 at linux.ibm.com>

> Reviewed-by: James Clark <james.clark at arm.com>
> Signed-off-by: Ian Rogers <irogers at 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[];
>  };
>  
>