On 03.04.2018 18:22, Jiri Olsa wrote:
> 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
Yep, will do. Thanks for noticing this.
Thanks,
Alexey
>
> 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) {
>
