From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752397AbeDCSDP (ORCPT ); Tue, 3 Apr 2018 14:03:15 -0400 Received: from mga09.intel.com ([134.134.136.24]:49547 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751461AbeDCSDO (ORCPT ); Tue, 3 Apr 2018 14:03:14 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,402,1517904000"; d="scan'208";a="30739329" Subject: Re: [PATCH v1] perf stat: enable 1ms interval for printing event counters values To: Jiri Olsa Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , Andi Kleen , linux-kernel References: <1480cba7-2307-8827-0ca6-0d6029ccdad9@linux.intel.com> <20180403152204.GA2313@krava> From: Alexey Budankov Organization: Intel Corp. Message-ID: Date: Tue, 3 Apr 2018 21:03:05 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180403152204.GA2313@krava> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >> --- >> 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) { >