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

Jiri Olsa
2019-10-30T10:06:16Z

On Fri, Oct 25, 2019 at 11:14:13AM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.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@linux.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