On Tue, Apr 03, 2018 at 06:04:13PM +0300, Alexey Budankov wrote:
>
> 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.budan...@linux.intel.com>
> ---
> tools/perf/builtin-stat.c | 14 ++------------
> 1 file changed, 2 insertions(+), 12 deletions(-)
I don't mind taking out the limit, but please update also
the stat man page, it mentiones the 10ms minimum
thanks,
jirka
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index f5c454855908..147a27e8c937 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -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) {
