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Subject[PATCH 1/2] perf tools: Add --quiet option to perf stat
Date
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>
---
tools/perf/Documentation/perf-stat.txt | 4 ++++
tools/perf/builtin-stat.c | 6 +++++-
tools/perf/util/stat.h | 1 +
3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 9f9f29025e49..b138dd192423 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -316,6 +316,10 @@ 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.
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index b01af171d94f..743fe47e7a88 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -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";

diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 487010c624be..05adf8165025 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -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;
--
2.28.0
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