linux-kernel - Re: [PATCH v3 3/7] perf evsel: Add iterator to iterate over events ordered by CPU

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Date:   Wed, 30 Oct 2019 11:06:06 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Andi Kleen <andi@...stfloor.org>
Cc:     acme@...nel.org, jolsa@...nel.org, eranian@...gle.com,
        linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v3 3/7] perf evsel: Add iterator to iterate over events
 ordered by CPU

On Fri, Oct 25, 2019 at 11:14:13AM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> Add some common code that is needed to iterate over all events
> in CPU order. Used in followon patches
> 
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> 
> ---
> 
> v2: Add cpumap__for_each_cpu macro to factor out some common code
> ---
>  tools/perf/util/cpumap.h |  8 ++++++++
>  tools/perf/util/evlist.c | 33 +++++++++++++++++++++++++++++++++
>  tools/perf/util/evlist.h |  4 ++++
>  tools/perf/util/evsel.h  |  1 +
>  4 files changed, 46 insertions(+)
> 
> diff --git a/tools/perf/util/cpumap.h b/tools/perf/util/cpumap.h
> index 2553bef1279d..a9b13d72fd29 100644
> --- a/tools/perf/util/cpumap.h
> +++ b/tools/perf/util/cpumap.h
> @@ -60,4 +60,12 @@ int cpu_map__build_map(struct perf_cpu_map *cpus, struct perf_cpu_map **res,
>  
>  int cpu_map__cpu(struct perf_cpu_map *cpus, int idx);
>  bool cpu_map__has(struct perf_cpu_map *cpus, int cpu);
> +
> +#define __cpumap__for_each_cpu(cpus, index, cpu, maxcpu)\
> +	for ((index) = 0; 				\
> +	     (cpu) = (index) < (maxcpu) ? (cpus)->map[index] : -1, (index) < (maxcpu); \
> +	     (index)++)
> +#define cpumap__for_each_cpu(cpus, index, cpu) \
> +	__cpumap__for_each_cpu(cpus, index, cpu, (cpus)->nr)
> +
>  #endif /* __PERF_CPUMAP_H */
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index fdce590d2278..da3c8f8ef68e 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -342,6 +342,39 @@ static int perf_evlist__nr_threads(struct evlist *evlist,
>  		return perf_thread_map__nr(evlist->core.threads);
>  }
>  
> +struct perf_cpu_map *evlist__cpu_iter_start(struct evlist *evlist)
> +{
> +	struct perf_cpu_map *cpus;
> +	struct evsel *pos;
> +
> +	/*
> +	 * evlist->cpus is not necessarily a superset of all the
> +	 * event's cpus, so compute our own super set. This
> +	 * assume that there is a super set
> +	 */
> +	cpus = evlist->core.cpus;
> +	evlist__for_each_entry(evlist, pos) {
> +		pos->cpu_index = 0;
> +		if (pos->core.cpus->nr > cpus->nr)
> +			cpus = pos->core.cpus;
> +	}
> +	return cpus;

I might not understand the reason for cpu_index, but 
imagine something like below should be enough, no?

	make evlist->all_cpus that contains all events cpus + evlist->core.cpus,
        and iterate it via:

	evlist__for_each_cpu(evlist, cpu) {
		affinity__set(&affinity, cpu);

		evlist__for_each_entry(evlist, evsel) {
			if (!cpu_map__has(perf_evsel__cpus(&evsel->core), cpu)
				continue;

			// here we have evsel with its cpu running on given cpu
		}
	}

jirka