From: Andi Kleen <a...@linux.intel.com>
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: Andi Kleen <a...@linux.intel.com>
---
tools/perf/builtin-stat.c | 97 ++++++++++++++++++++++-----------------
tools/perf/util/evsel.h | 1 +
2 files changed, 57 insertions(+), 41 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 651ee9ddf0a3..b52121bb28a3 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -264,15 +264,10 @@ 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(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;
@@ -281,40 +276,38 @@ 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.
- */
- if (!perf_counts__is_loaded(counter->counts, cpu,
thread) &&
- read_single_counter(counter, cpu, thread, rs)) {
- counter->counts->scaled = -1;
- perf_counts(counter->counts, cpu, thread)->ena
= 0;
- perf_counts(counter->counts, cpu, thread)->run
= 0;
- return -1;
- }
+ struct perf_counts_values *count;
- perf_counts__set_loaded(counter->counts, cpu, thread,
false);
+ count = perf_counts(counter->counts, cpu, thread);
- if (STAT_RECORD) {
- if (perf_evsel__write_stat_event(counter, cpu,
thread, count)) {
- pr_err("failed to write stat event\n");
- return -1;
- }
- }
+ /*
+ * The leader's group read loads data into its group members
+ * (via perf_evsel__read_counter) and sets threir count->loaded.
+ */
+ if (!perf_counts__is_loaded(counter->counts, cpu, thread) &&
+ read_single_counter(counter, cpu, thread, rs)) {
+ counter->counts->scaled = -1;
+ perf_counts(counter->counts, cpu, thread)->ena = 0;
+ perf_counts(counter->counts, cpu, thread)->run = 0;
+ return -1;
+ }
+
+ perf_counts__set_loaded(counter->counts, cpu, thread, false);
- if (verbose > 1) {
- fprintf(stat_config.output,
- "%s: %d: %" PRIu64 " %" PRIu64 " %"
PRIu64 "\n",
- perf_evsel__name(counter),
- cpu,
- count->val, count->ena,
count->run);
+ if (STAT_RECORD) {
+ if (perf_evsel__write_stat_event(counter, cpu, thread,
count)) {
+ pr_err("failed to write stat event\n");
+ return -1;
}
}
+
+ if (verbose > 1) {
+ fprintf(stat_config.output,
+ "%s: %d: %" PRIu64 " %" PRIu64 " %" PRIu64 "\n",
+ perf_evsel__name(counter),
+ cpu,
+ count->val, count->ena, count->run);
+ }
}
return 0;
@@ -323,15 +316,37 @@ 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;
+ struct perf_cpu_map *cpus;
+
+ if (affinity__setup(&affinity) < 0)
+ return;
+
+ cpus = evlist__cpu_iter_start(evsel_list);
+
+ ncpus = cpus->nr;
+ if (!(target__has_cpu(&target) && !target__has_per_thread(&target)))
+ ncpus = 1;
+ for (i = 0; i < ncpus; i++) {
+ int cpu = cpus->map[i];
+ affinity__set(&affinity, cpu);
+
+ evlist__for_each_entry(evsel_list, counter) {
+ if (evlist__cpu_iter_skip(counter, cpu))
+ continue;
+ counter->err = read_counter(counter, rs,
counter->cpu_index);
+ evlist__cpu_iter_next(counter);
+ }
+ }
+ affinity__cleanup(&affinity);
evlist__for_each_entry(evsel_list, counter) {
- ret = read_counter(counter, rs);
- if (ret)
+ if (counter->err)
pr_debug("failed to read counter %s\n", counter->name);
-
- if (ret == 0 && perf_stat_process_counter(&stat_config,
counter))
+ if (counter->err == 0 &&
perf_stat_process_counter(&stat_config, counter))
pr_warning("failed to process counter %s\n",
counter->name);
+ counter->err = 0;
}
}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 28692abe1d42..ef87b76c0565 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -163,6 +163,7 @@ 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;
--
2.21.0
