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Message-ID: <20180215133921.GC22818@kernel.org>
Date: Thu, 15 Feb 2018 10:39:21 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: ufo19890607 <ufo19890607@...il.com>
Cc: peterz@...radead.org, mingo@...hat.com,
alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
dsahern@...il.com, namhyung@...nel.org, milian.wolff@...b.com,
arnaldo.melo@...il.com, yuzhoujian@...ichuxing.com,
adrian.hunter@...el.com, wangnan0@...wei.com, Kan.liang@...el.com,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
acme@...hat.com
Subject: Re: [PATCH v4 2/2] perf stat: Add support to print counts after a
period of time
Em Mon, Jan 29, 2018 at 10:25:23AM +0100, ufo19890607 escreveu:
> From: yuzhoujian <yuzhoujian@...ichuxing.com>
>
> Introduce a new option to print counts after N milliseconds
This doesn't just print counts after N ms, it _stops_ the workload after
that time _and_ prints the counts, right?
Can you please send a followup patch fixing the description and
documentation?
I've applied this already, but clarifying what this option does is in
demand.
- Arnaldo
> and update perf-stat documentation accordingly.
>
> Show below is the output of the new option for perf stat.
>
> $ perf stat --time 2000 -e cycles -a
> Performance counter stats for 'system wide':
>
> 157,260,423 cycles
>
> 2.003060766 seconds time elapsed
>
> We can print the count deltas after N milliseconds with this new
> introduced option. This option is not supported with "-I" option.
> In addition, according to Kangliang's patch(19afd10410957), the
> monitoring overhead for system-wide core event could be very high
> if the interval-print parameter was below 100ms, and the limitation
> value is 10ms. So the same warning will be displayed when the time
> is set between 10ms to 100ms, and the minimal time is limited to
> 10ms. Users can make a decision according to their spcific cases.
>
> Changes since v3:
> - none.
>
> Changes since v2:
> - modify the time check in __run_perf_stat func to keep some consistency
> with the workload case.
> - add the warning when the time is set between 10ms to 100ms.
> - add the pr_err when the time is set below 10ms.
>
> Changes since v1:
> - none.
>
> Signed-off-by: yuzhoujian <yuzhoujian@...ichuxing.com>
> ---
> tools/perf/Documentation/perf-stat.txt | 5 +++++
> tools/perf/builtin-stat.c | 33 +++++++++++++++++++++++++++++++--
> tools/perf/util/stat.h | 1 +
> 3 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
> index 47a21645f60c..c822f374c99a 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -151,6 +151,11 @@ Print count deltas for fixed number of times.
> This option should be used together with "-I" option.
> example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
>
> +--time msecs::
> +Print count deltas after N milliseconds (minimum: 10 ms).
> +This option is not supported with "-I" option.
> + example: 'perf stat --time 2000 -e cycles -a'
> +
> --metric-only::
> Only print computed metrics. Print them in a single line.
> Don't show any raw values. Not supported with --per-thread.
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 7d1d7613bf56..582db3897374 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -573,6 +573,7 @@ static int __run_perf_stat(int argc, const char **argv)
> {
> int interval = stat_config.interval;
> int times = stat_config.times;
> + int time = stat_config.time;
> char msg[BUFSIZ];
> unsigned long long t0, t1;
> struct perf_evsel *counter;
> @@ -586,6 +587,9 @@ static int __run_perf_stat(int argc, const char **argv)
> if (interval) {
> ts.tv_sec = interval / USEC_PER_MSEC;
> ts.tv_nsec = (interval % USEC_PER_MSEC) * NSEC_PER_MSEC;
> + } else if (time) {
> + ts.tv_sec = time / USEC_PER_MSEC;
> + ts.tv_nsec = (time % USEC_PER_MSEC) * NSEC_PER_MSEC;
> } else {
> ts.tv_sec = 1;
> ts.tv_nsec = 0;
> @@ -698,9 +702,11 @@ static int __run_perf_stat(int argc, const char **argv)
> perf_evlist__start_workload(evsel_list);
> enable_counters();
>
> - if (interval) {
> + if (interval || time) {
> while (!waitpid(child_pid, &status, WNOHANG)) {
> nanosleep(&ts, NULL);
> + if (time)
> + break;
> process_interval();
> if (interval_count && !(--times))
> break;
> @@ -720,6 +726,8 @@ static int __run_perf_stat(int argc, const char **argv)
> enable_counters();
> while (!done) {
> nanosleep(&ts, NULL);
> + if (time)
> + break;
> if (interval) {
> process_interval();
> if (interval_count && !(--times))
> @@ -1900,6 +1908,8 @@ static const struct option stat_options[] = {
> "print counts at regular interval in ms (>= 10)"),
> OPT_INTEGER(0, "interval-count", &stat_config.times,
> "print counts for fixed number of times"),
> + OPT_UINTEGER(0, "time", &stat_config.time,
> + "print counts after a period of time in ms (>= 10)"),
> OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
> "aggregate counts per processor socket", AGGR_SOCKET),
> OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
> @@ -2697,7 +2707,7 @@ int cmd_stat(int argc, const char **argv)
> int status = -EINVAL, run_idx;
> const char *mode;
> FILE *output = stderr;
> - unsigned int interval;
> + unsigned int interval, time;
> const char * const stat_subcommands[] = { "record", "report" };
>
> setlocale(LC_ALL, "");
> @@ -2728,6 +2738,7 @@ int cmd_stat(int argc, const char **argv)
> return __cmd_report(argc, argv);
>
> interval = stat_config.interval;
> + time = stat_config.time;
>
> /*
> * For record command the -o is already taken care of.
> @@ -2879,6 +2890,7 @@ int cmd_stat(int argc, const char **argv)
> "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) {
> @@ -2889,6 +2901,23 @@ int cmd_stat(int argc, const char **argv)
> goto out;
> }
>
> + if (time && time < 100) {
> + if (time < 10) {
> + pr_err("time must be >= 10ms.\n");
> + parse_options_usage(stat_usage, stat_options, "time", 0);
> + goto out;
> + } else
> + pr_warning("time < 100ms. "
> + "The overhead percentage could be high in some cases. "
> + "Please proceed with caution.\n");
> + }
> + if (time && interval) {
> + pr_err("time option is not supported with interval-print.\n");
> + parse_options_usage(stat_usage, stat_options, "time", 0);
> + parse_options_usage(stat_usage, stat_options, "I", 1);
> + goto out;
> + }
> +
> if (perf_evlist__alloc_stats(evsel_list, interval))
> goto out;
>
> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
> index 540fbb350e53..fc1ab635f7e0 100644
> --- a/tools/perf/util/stat.h
> +++ b/tools/perf/util/stat.h
> @@ -90,6 +90,7 @@ struct perf_stat_config {
> bool scale;
> FILE *output;
> unsigned int interval;
> + unsigned int time;
> int times;
> struct runtime_stat *stats;
> int stats_num;
> --
> 2.14.1
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