linux-kernel - Re: [PATCH 3/5] perf cpumap: Add intersect function.

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Date:   Mon, 28 Mar 2022 17:28:18 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Kajol Jain <kjain@...ux.ibm.com>,
        James Clark <james.clark@....com>,
        German Gomez <german.gomez@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 3/5] perf cpumap: Add intersect function.

Em Sun, Mar 27, 2022 at 11:24:12PM -0700, Ian Rogers escreveu:
> The merge function gives the union of two cpu maps. Add an intersect
> function which will be used in the next change.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/lib/perf/cpumap.c              | 38 ++++++++++++++++++++++++++++
>  tools/lib/perf/include/perf/cpumap.h |  2 ++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> index 953bc50b0e41..56b4d213039f 100644
> --- a/tools/lib/perf/cpumap.c
> +++ b/tools/lib/perf/cpumap.c
> @@ -393,3 +393,41 @@ struct perf_cpu_map *perf_cpu_map__merge(struct perf_cpu_map *orig,
>  	perf_cpu_map__put(orig);
>  	return merged;
>  }
> +
> +struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig,
> +					     struct perf_cpu_map *other)
> +{
> +	struct perf_cpu *tmp_cpus;
> +	int tmp_len;
> +	int i, j, k;
> +	struct perf_cpu_map *merged = NULL;
> +
> +	if (perf_cpu_map__is_subset(other, orig))
> +		return orig;
> +	if (perf_cpu_map__is_subset(orig, other)) {
> +		perf_cpu_map__put(orig);

Why this put(orig)?

> +		return perf_cpu_map__get(other);

And why the get here and not on the first if?

> +	}
> +
> +	tmp_len = max(orig->nr, other->nr);
> +	tmp_cpus = malloc(tmp_len * sizeof(struct perf_cpu));
> +	if (!tmp_cpus)
> +		return NULL;
> +
> +	i = j = k = 0;
> +	while (i < orig->nr && j < other->nr) {
> +		if (orig->map[i].cpu < other->map[j].cpu)
> +			i++;
> +		else if (orig->map[i].cpu > other->map[j].cpu)
> +			j++;
> +		else {
> +			j++;
> +			tmp_cpus[k++] = orig->map[i++];
> +		}
> +	}
> +	if (k)
> +		merged = cpu_map__trim_new(k, tmp_cpus);
> +	free(tmp_cpus);
> +	perf_cpu_map__put(orig);
> +	return merged;
> +}
> diff --git a/tools/lib/perf/include/perf/cpumap.h b/tools/lib/perf/include/perf/cpumap.h
> index 4a2edbdb5e2b..a2a7216c0b78 100644
> --- a/tools/lib/perf/include/perf/cpumap.h
> +++ b/tools/lib/perf/include/perf/cpumap.h
> @@ -19,6 +19,8 @@ LIBPERF_API struct perf_cpu_map *perf_cpu_map__read(FILE *file);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map);
>  LIBPERF_API struct perf_cpu_map *perf_cpu_map__merge(struct perf_cpu_map *orig,
>  						     struct perf_cpu_map *other);
> +LIBPERF_API struct perf_cpu_map *perf_cpu_map__intersect(struct perf_cpu_map *orig,
> +							 struct perf_cpu_map *other);
>  LIBPERF_API void perf_cpu_map__put(struct perf_cpu_map *map);
>  LIBPERF_API struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx);
>  LIBPERF_API int perf_cpu_map__nr(const struct perf_cpu_map *cpus);
> -- 
> 2.35.1.1021.g381101b075-goog

-- 

- Arnaldo