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Commit 9dc9a95f authored by Alexey Budankov's avatar Alexey Budankov Committed by Arnaldo Carvalho de Melo
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perf stat: Enable 1ms interval for printing event counters values 



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: default avatarAlexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: default avatarJiri 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 50268a3d

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) {