Re: [PATCH 21/22] perf cpumap: Trim the cpu_aggr_map

[Jiri Olsa]

On Tue, Dec 07, 2021 at 06:46:06PM -0800, Ian Rogers wrote:
> cpu_aggr_map__new removes duplicates, when this happens shrink the
> array.
> 
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
>  tools/perf/util/cpumap.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
> index 8a72ee996722..985c87f1f1ca 100644
> --- a/tools/perf/util/cpumap.c
> +++ b/tools/perf/util/cpumap.c
> @@ -185,7 +185,12 @@ struct cpu_aggr_map *cpu_aggr_map__new(const struct perf_cpu_map *cpus,
>  			c->nr++;
>  		}
>  	}
> -
> +	/* Trim. */
> +	if (c->nr != cpus->nr) {
> +		c = realloc(c, sizeof(struct cpu_aggr_map) + sizeof(struct aggr_cpu_id) * c->nr);
> +		if (!c)
> +			return NULL;
> +	}

curious.. we should do this, but did you detect some big waste in here?

thanks,
jirka

>  	/* ensure we process id in increasing order */
>  	qsort(c->map, c->nr, sizeof(struct aggr_cpu_id), aggr_cpu_id__cmp);
>  
> -- 
> 2.34.1.400.ga245620fadb-goog
>