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perf stat: Add --quiet option 

Add a new --quiet option to 'perf stat'. This is useful with 'perf stat
record' to write the data only to the perf.data file, which can lower
measurement overhead because the data doesn't need to be formatted.

On my 4C desktop:

  % time ./perf stat record  -e $(python -c 'print ",".join(["cycles"]*1000)')  -a -I 1000 sleep 5
  ...
  real    0m5.377s
  user    0m0.238s
  sys     0m0.452s
  % time ./perf stat record --quiet -e $(python -c 'print ",".join(["cycles"]*1000)')  -a -I 1000 sleep 5

  real    0m5.452s
  user    0m0.183s
  sys     0m0.423s

In this example it cuts the user time by 20%. On systems with more cores
the savings are higher.

Signed-off-by: Andi Kleen <andi@firstfloor.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Link: http://lore.kernel.org/lkml/20201027002737.30942-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Andi Kleen 2020-10-26 17:27:36 -07:00 committed by Arnaldo Carvalho de Melo
parent bb1c15b60b
commit 55a4de94c6
3 changed files with 10 additions and 1 deletions
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4
tools/perf/Documentation/perf-stat.txt
View File

@ -317,6 +317,10 @@ small group that need not have multiplexing is lowered. This option
forbids the event merging logic from sharing events between groups and
may be used to increase accuracy in this case.
--quiet::
Don't print output. This is useful with perf stat record below to only
write data to the perf.data file.
STAT RECORD
-----------
Stores stat data into perf data file.

6
tools/perf/builtin-stat.c
View File

@ -972,6 +972,8 @@ static void print_counters(struct timespec *ts, int argc, const char **argv)
/* Do not print anything if we record to the pipe. */
if (STAT_RECORD && perf_stat.data.is_pipe)
return;
if (stat_config.quiet)
return;
perf_evlist__print_counters(evsel_list, &stat_config, &target,
ts, argc, argv);
@ -1171,6 +1173,8 @@ static struct option stat_options[] = {
"threads of same physical core"),
OPT_BOOLEAN(0, "summary", &stat_config.summary,
"print summary for interval mode"),
OPT_BOOLEAN(0, "quiet", &stat_config.quiet,
"don't print output (useful with record)"),
#ifdef HAVE_LIBPFM
OPT_CALLBACK(0, "pfm-events", &evsel_list, "event",
"libpfm4 event selector. use 'perf list' to list available events",
@ -2132,7 +2136,7 @@ int cmd_stat(int argc, const char **argv)
goto out;
}
if (!output) {
if (!output && !stat_config.quiet) {
struct timespec tm;
mode = append_file ? "a" : "w";

1
tools/perf/util/stat.h
View File

@ -122,6 +122,7 @@ struct perf_stat_config {
bool metric_no_group;
bool metric_no_merge;
bool stop_read_counter;
bool quiet;
FILE *output;
unsigned int interval;
unsigned int timeout;