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perf stat: No need to setup affinities when starting a workload

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I.e. the simple:

  $ perf stat sleep 1

Uses a dummy CPU map and thus there is no need to setup/cleanup
affinities to avoid IPIs, etc.

With this we're down to a sched_getaffinity() call, in the libnuma
initialization, that probably can be removed in a followup patch.

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220117160931.1191712-3-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2022-01-17 13:09:29 -03:00
parent 1855b796f2
commit 49de179577
1 changed files with 10 additions and 7 deletions
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15
tools/perf/builtin-stat.c
View file

@ -788,7 +788,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
const bool forks = (argc > 0); const bool forks = (argc > 0);
bool is_pipe = STAT_RECORD ? perf_stat.data.is_pipe : false; bool is_pipe = STAT_RECORD ? perf_stat.data.is_pipe : false;
struct evlist_cpu_iterator evlist_cpu_itr; struct evlist_cpu_iterator evlist_cpu_itr;
struct affinity affinity; struct affinity saved_affinity, *affinity = NULL;
int err; int err;
bool second_pass = false; bool second_pass = false;
@ -803,8 +803,11 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
if (group) if (group)
evlist__set_leader(evsel_list); evlist__set_leader(evsel_list);
if (affinity__setup(&affinity) < 0) if (!cpu_map__is_dummy(evsel_list->core.cpus)) {
if (affinity__setup(&saved_affinity) < 0)
return -1; return -1;
affinity = &saved_affinity;
}
evlist__for_each_entry(evsel_list, counter) { evlist__for_each_entry(evsel_list, counter) {
if (bpf_counter__load(counter, &target)) if (bpf_counter__load(counter, &target))
@ -813,7 +816,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
all_counters_use_bpf = false; all_counters_use_bpf = false;
} }
evlist__for_each_cpu(evlist_cpu_itr, evsel_list, &affinity) { evlist__for_each_cpu(evlist_cpu_itr, evsel_list, affinity) {
counter = evlist_cpu_itr.evsel; counter = evlist_cpu_itr.evsel;
/* /*
@ -869,7 +872,7 @@ try_again:
*/ */
/* First close errored or weak retry */ /* First close errored or weak retry */
evlist__for_each_cpu(evlist_cpu_itr, evsel_list, &affinity) { evlist__for_each_cpu(evlist_cpu_itr, evsel_list, affinity) {
counter = evlist_cpu_itr.evsel; counter = evlist_cpu_itr.evsel;
if (!counter->reset_group && !counter->errored) if (!counter->reset_group && !counter->errored)
@ -878,7 +881,7 @@ try_again:
perf_evsel__close_cpu(&counter->core, evlist_cpu_itr.cpu_map_idx); perf_evsel__close_cpu(&counter->core, evlist_cpu_itr.cpu_map_idx);
} }
/* Now reopen weak */ /* Now reopen weak */
evlist__for_each_cpu(evlist_cpu_itr, evsel_list, &affinity) { evlist__for_each_cpu(evlist_cpu_itr, evsel_list, affinity) {
counter = evlist_cpu_itr.evsel; counter = evlist_cpu_itr.evsel;
if (!counter->reset_group && !counter->errored) if (!counter->reset_group && !counter->errored)
@ -904,7 +907,7 @@ try_again_reset:
counter->supported = true; counter->supported = true;
} }
} }
affinity__cleanup(&affinity); affinity__cleanup(affinity);
evlist__for_each_entry(evsel_list, counter) { evlist__for_each_entry(evsel_list, counter) {
if (!counter->supported) { if (!counter->supported) {