From f9cef0a90c4e7637f1ec98474a1a099aec45eb65 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 28 Apr 2011 18:17:11 +0200 Subject: perf stat: Add --sync/-S option --sync will tell perf stat to run sync() before starting a command. This allows IO-heavy tests to be used with --repeat, without one iteration impacting the other. Elapsed time will stabilize for example: before: 3.971525714 seconds time elapsed ( +- 8.56% ) after: 3.211098537 seconds time elapsed ( +- 1.52% ) So measurements will be more accurate. Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Link: http://lkml.kernel.org/n/tip-7y40wib8n1eqio7hjpn1dsrm@git.kernel.org Signed-off-by: Ingo Molnar --- tools/perf/builtin-stat.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'tools') diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 003caa857a44..5658a770dbd7 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -128,6 +128,7 @@ static pid_t target_tid = -1; static pid_t child_pid = -1; static bool null_run = false; static bool detailed_run = false; +static bool sync_run = false; static bool big_num = true; static int big_num_opt = -1; static const char *cpu_list; @@ -819,6 +820,8 @@ static const struct option options[] = { "null run - dont start any counters"), OPT_BOOLEAN('d', "detailed", &detailed_run, "detailed run - start a lot of events"), + OPT_BOOLEAN('S', "sync", &sync_run, + "call sync() before starting a run"), OPT_CALLBACK_NOOPT('B', "big-num", NULL, NULL, "print large numbers with thousands\' separators", stat__set_big_num), @@ -944,6 +947,10 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used) for (run_idx = 0; run_idx < run_count; run_idx++) { if (run_count != 1 && verbose) fprintf(stderr, "[ perf stat: executing run #%d ... ]\n", run_idx + 1); + + if (sync_run) + sync(); + status = run_perf_stat(argc, argv); } -- cgit v1.2.1