[PATCH] perf bench: flush stats when pipe it to a file or to tee

Sohaib Mohamed
2021-11-12T21:54:00Z

The output of perf bench gets buffered when I pipe it to a file or to
tee, in such a way that I can see it only at the end.

E.g.
$ perf bench internals synthesize -t
< output comes out fine after each test run >

$ perf bench internals synthesize -t | tee file.txt
< output comes out only at the end of all tests >

See, also:
$ perf bench mem all | tee file.txt
$ perf bench sched all | tee file.txt
$ perf bench internals all -t | tee file.txt
$ perf bench internals all | tee file.txt

Suggested-by: Riccardo Mancini <rickyman7@gmail.com>
Signed-off-by: Sohaib Mohamed <sohaib.amhmd@gmail.com>
---
tools/perf/bench/find-bit-bench.c | 1 +
tools/perf/bench/synthesize.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/tools/perf/bench/find-bit-bench.c b/tools/perf/bench/find-bit-bench.c
index 22b5cfe97023..39fb4184fbcb 100644
--- a/tools/perf/bench/find-bit-bench.c
+++ b/tools/perf/bench/find-bit-bench.c
@@ -113,6 +113,7 @@ static int do_for_each_set_bit(unsigned int num_bits)

if (use_of_val == accumulator) /* Try to avoid compiler tricks. */
printf("\n");
+ fflush(stdout);
}
bitmap_free(to_test);
return 0;
diff --git a/tools/perf/bench/synthesize.c b/tools/perf/bench/synthesize.c
index 7401ebbac100..d21d311df61b 100644
--- a/tools/perf/bench/synthesize.c
+++ b/tools/perf/bench/synthesize.c
@@ -92,6 +92,7 @@ static int do_run_single_threaded(struct perf_session *session,
update_stats(&event_stats, atomic_read(&event_count));
}

+ fflush(stdout);
time_average = avg_stats(&time_stats);
time_stddev = stddev_stats(&time_stats);
printf(" Average %ssynthesis took: %.3f usec (+- %.3f usec)\n",
@@ -186,6 +187,7 @@ static int do_run_multi_threaded(struct target *target,
perf_session__delete(session);
}

+ fflush(stdout);
time_average = avg_stats(&time_stats);
time_stddev = stddev_stats(&time_stats);
printf(" Average synthesis took: %.3f usec (+- %.3f usec)\n",
--
2.25.1