diff options
| -rw-r--r-- | tools/perf/Documentation/perf-stat.txt | 5 | ||||
| -rw-r--r-- | tools/perf/builtin-stat.c | 13 |
2 files changed, 12 insertions, 6 deletions
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt index 47469abdcc1c..4e074a660826 100644 --- a/tools/perf/Documentation/perf-stat.txt +++ b/tools/perf/Documentation/perf-stat.txt @@ -128,8 +128,9 @@ perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- m -I msecs:: --interval-print msecs:: - Print count deltas every N milliseconds (minimum: 100ms) - example: perf stat -I 1000 -e cycles -a sleep 5 +Print count deltas every N milliseconds (minimum: 10ms) +The overhead percentage could be high in some cases, for instance with small, sub 100ms intervals. Use with caution. + example: 'perf stat -I 1000 -e cycles -a sleep 5' --per-socket:: Aggregate counts per processor socket for system-wide mode measurements. This diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index a96fb5c3bedb..5ef88f760b12 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -1179,7 +1179,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused) OPT_STRING(0, "post", &post_cmd, "command", "command to run after to the measured command"), OPT_UINTEGER('I', "interval-print", &stat_config.interval, - "print counts at regular interval in ms (>= 100)"), + "print counts at regular interval in ms (>= 10)"), OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode, "aggregate counts per processor socket", AGGR_SOCKET), OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode, @@ -1332,9 +1332,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused) thread_map__read_comms(evsel_list->threads); if (interval && interval < 100) { - pr_err("print interval must be >= 100ms\n"); - parse_options_usage(stat_usage, options, "I", 1); - goto out; + if (interval < 10) { + pr_err("print interval must be >= 10ms\n"); + parse_options_usage(stat_usage, options, "I", 1); + goto out; + } else + pr_warning("print interval < 100ms. " + "The overhead percentage could be high in some cases. " + "Please proceed with caution.\n"); } if (perf_evlist__alloc_stats(evsel_list, interval)) |