perf stat: Enable 1ms interval for printing event counters values (9dc9a95f) · Commits · 戴 / test

Currently print count interval for performance counters values is limited by 10ms so reading the values at frequencies higher than 100Hz is restricted by the tool. This change makes perf stat -I possible on frequencies up to 1KHz and, to some extent, makes perf stat -I to be on-par with perf record sampling profiling. When running perf stat -I for monitoring e.g. PCIe uncore counters and at the same time profiling some I/O workload by perf record e.g. for cpu-cycles and context switches, it is then possible to observe consolidated CPU/OS/IO(Uncore) performance picture for that workload. Tool overhead warning printed when specifying -v option can be missed due to screen scrolling in case you have output to the console so message is moved into help available by running perf stat -h. Signed-off-by:

Alexey Budankov <alexey.budankov@linux.intel.com> Acked-by:

Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/b842ad6a-d606-32e4-afe5-974071b5198e@linux.intel.com Signed-off-by:

Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-stat.txt

+1 −1

Original line number	Diff line number	Diff line
		@@ -153,7 +153,7 @@ 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: 10ms)
		Print count deltas every N milliseconds (minimum: 1ms)
		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'

tools/perf/builtin-stat.c

+2 −12

Original line number	Diff line number	Diff line
		@@ -1943,7 +1943,8 @@ static const struct option stat_options[] = {
		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 (>= 10)"),
		"print counts at regular interval in ms "
		"(overhead is possible for values <= 100ms)"),
		OPT_INTEGER(0, "interval-count", &stat_config.times,
		"print counts for fixed number of times"),
		OPT_UINTEGER(0, "timeout", &stat_config.timeout,
		@@ -2923,17 +2924,6 @@ int cmd_stat(int argc, const char **argv)
		}
		}

		if (interval && interval < 100) {
		if (interval < 10) {
		pr_err("print interval must be >= 10ms\n");
		parse_options_usage(stat_usage, stat_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 (stat_config.times && interval)
		interval_count = true;
		else if (stat_config.times && !interval) {

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