Commit 4b49ab70 authored by Andi Kleen's avatar Andi Kleen Committed by Arnaldo Carvalho de Melo
Browse files

perf stat: Use affinity for reading 



Restructure event reading to use affinity to minimize the number of IPIs
needed.

Before on a large test case with 94 CPUs:

  % time     seconds  usecs/call     calls    errors syscall
  ------ ----------- ----------- --------- --------- ----------------
    3.16    0.106079           4     22082           read

After:

    3.43    0.081295           3     22082           read

Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191121001522.180827-11-andi@firstfloor.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 4804e011

tools/perf/builtin-stat.c

+56 −41
Original line number Diff line number Diff line
@@ -266,15 +266,10 @@ static int read_single_counter(struct evsel *counter, int cpu, 
 * Read out the results of a single counter:

 * do not aggregate counts across CPUs in system-wide mode

 */

static int read_counter(struct evsel *counter, struct timespec *rs)

static int read_counter_cpu(struct evsel *counter, struct timespec *rs, int cpu)

{

	int nthreads = perf_thread_map__nr(evsel_list->core.threads);

	int ncpus, cpu, thread;



	if (target__has_cpu(&target) && !target__has_per_thread(&target))

		ncpus = perf_evsel__nr_cpus(counter);

	else

		ncpus = 1;

	int thread;



	if (!counter->supported)

		return -ENOENT;
@@ -283,14 +278,13 @@ static int read_counter(struct evsel *counter, struct timespec *rs) 
		nthreads = 1;



	for (thread = 0; thread < nthreads; thread++) {

		for (cpu = 0; cpu < ncpus; cpu++) {

		struct perf_counts_values *count;



		count = perf_counts(counter->counts, cpu, thread);



		/*

		 * The leader's group read loads data into its group members

			 * (via perf_evsel__read_counter) and sets threir count->loaded.

		 * (via perf_evsel__read_counter()) and sets their count->loaded.

		 */

		if (!perf_counts__is_loaded(counter->counts, cpu, thread) &&

		    read_single_counter(counter, cpu, thread, rs)) {
@@ -317,7 +311,6 @@ static int read_counter(struct evsel *counter, struct timespec *rs) 
					count->val, count->ena, count->run);

		}

	}

	}



	return 0;

}
@@ -325,15 +318,37 @@ static int read_counter(struct evsel *counter, struct timespec *rs) 
static void read_counters(struct timespec *rs)

{

	struct evsel *counter;

	int ret;

	struct affinity affinity;

	int i, ncpus, cpu;



	if (affinity__setup(&affinity) < 0)

		return;



	ncpus = perf_cpu_map__nr(evsel_list->core.all_cpus);

	if (!target__has_cpu(&target) || target__has_per_thread(&target))

		ncpus = 1;

	evlist__for_each_cpu(evsel_list, i, cpu) {

		if (i >= ncpus)

			break;

		affinity__set(&affinity, cpu);



		evlist__for_each_entry(evsel_list, counter) {

		ret = read_counter(counter, rs);

		if (ret)

			pr_debug("failed to read counter %s\n", counter->name);

			if (evsel__cpu_iter_skip(counter, cpu))

				continue;

			if (!counter->err) {

				counter->err = read_counter_cpu(counter, rs,

								counter->cpu_iter - 1);

			}

		}

	}

	affinity__cleanup(&affinity);



		if (ret == 0 && perf_stat_process_counter(&stat_config, counter))

	evlist__for_each_entry(evsel_list, counter) {

		if (counter->err)

			pr_debug("failed to read counter %s\n", counter->name);

		if (counter->err == 0 && perf_stat_process_counter(&stat_config, counter))

			pr_warning("failed to process counter %s\n", counter->name);

		counter->err = 0;

	}

}

tools/perf/util/evsel.h

+1 −0
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ struct evsel { 
	struct list_head	config_terms;

	struct bpf_object	*bpf_obj;

	int			bpf_fd;

	int			err;

	bool			auto_merge_stats;

	bool			merged_stat;

	const char *		metric_expr;

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