linux-kernel - Re: [RFC PATCH v1 02/37] libperf cpumap: improve max function

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Date:   Tue, 31 Aug 2021 15:47:10 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Riccardo Mancini <rickyman7@...il.com>
Cc:     Ian Rogers <irogers@...gle.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [RFC PATCH v1 02/37] libperf cpumap: improve max function

Em Sat, Aug 21, 2021 at 11:19:08AM +0200, Riccardo Mancini escreveu:
> >From commit 7074674e7338863e ("perf cpumap: Maintain cpumaps ordered and
> without dups"), perf_cpu_map elements are sorted in ascending order.
> 
> This patch improves the perf_cpu_map__max function by returning the last
> element.
> 
> Signed-off-by: Riccardo Mancini <rickyman7@...il.com>
> ---
>  tools/lib/perf/cpumap.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> index fb633272be3aaed9..80e03b2f0c60cce7 100644
> --- a/tools/lib/perf/cpumap.c
> +++ b/tools/lib/perf/cpumap.c
> @@ -284,14 +284,10 @@ int perf_cpu_map__idx(struct perf_cpu_map *cpus, int cpu)
>  
>  int perf_cpu_map__max(struct perf_cpu_map *map)
>  {
> -	int i, max = -1;
> -
> -	for (i = 0; i < map->nr; i++) {
> -		if (map->map[i] > max)
> -			max = map->map[i];
> -	}
> -
> -	return max;
> +	if (map->nr > 0)
> +		return map->map[map->nr-1];
> +	else
> +		return -1;

Applying, but adding spaces around the '-',

Thanks.

- Arnaldo