From: Jiri Olsa <jolsa@redhat.com>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v9 11/15] perf stat: implement control commands handling
Date: Tue, 7 Jul 2020 15:14:03 +0200 [thread overview]
Message-ID: <20200707131403.GD3424581@krava> (raw)
In-Reply-To: <b28806b9-b66e-aa2e-5425-4d9f00341387@linux.intel.com>
On Tue, Jul 07, 2020 at 04:07:42PM +0300, Alexey Budankov wrote:
>
> On 06.07.2020 22:34, Jiri Olsa wrote:
> > On Mon, Jul 06, 2020 at 05:47:54PM +0300, Alexey Budankov wrote:
> >>
> >> On 06.07.2020 15:34, Jiri Olsa wrote:
> >>> On Fri, Jul 03, 2020 at 10:47:22AM +0300, Alexey Budankov wrote:
> >>>>
> >>>> Implement handling of 'enable' and 'disable' control commands
> >>>> coming from control file descriptor. process_evlist() function
> >>>> checks for events on control fds and makes required operations.
> >>>> If poll event splits initiated timeout interval then the reminder
> >>>> is calculated and still waited in the following poll() syscall.
> >>>>
> >>>> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> >>>> ---
> >>>> tools/perf/builtin-stat.c | 75 ++++++++++++++++++++++++++++-----------
> >>>> 1 file changed, 55 insertions(+), 20 deletions(-)
> >>>>
> >>>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> >>>> index 9e4288ecf2b8..5021f7286422 100644
> >>>> --- a/tools/perf/builtin-stat.c
> >>>> +++ b/tools/perf/builtin-stat.c
> >>>> @@ -485,6 +485,31 @@ static bool handle_interval(unsigned int interval, int *times)
> >>>> return false;
> >>>> }
> >>>>
> >>>> +static bool process_evlist(struct evlist *evlist, unsigned int interval, int *times)
> >>>> +{
> >>>> + bool stop = false;
> >>>> + enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
> >>>> +
> >>>> + if (evlist__ctlfd_process(evlist, &cmd) > 0) {
> >>>> + switch (cmd) {
> >>>> + case EVLIST_CTL_CMD_ENABLE:
> >>>> + pr_info(EVLIST_ENABLED_MSG);
> >>>> + stop = handle_interval(interval, times);
> >>>> + break;
> >>>> + case EVLIST_CTL_CMD_DISABLE:
> >>>> + stop = handle_interval(interval, times);
> >>>
> >>> I still don't understand why you call handle_interval in here
> >>>
> >>> I don't see it being necessary.. you enable events and handle_interval,
> >>> wil be called in the next iteration of dispatch_events, why complicate
> >>> this function with that?
> >>
> >> Printing event counts at the moment of command processing lets scripts
> >> built on top of stat output to provide more plain and accurate metrics.
> >> Otherwise it may get spikes in the beginning of the next time interval
> >> because not all counts lay inside [Events enabled, Events disable]
> >> If -I interval is large tail event count can be also large. Compare the
> >> output below with the output in the cover letter. Either way is possible
> >> but the latter one likely complicates the scripts I mentioned above.
> >>
> >> perf=tools/perf/perf
> >> ${perf} stat -D -1 -e cpu-cycles -a -I 1000 \
> >> --control fd:${ctl_fd},${ctl_fd_ack} \
> >> -- sleep 40 &
> >>
> >> Events disabled
> >> # time counts unit events
> >> 1.001100723 <not counted> cpu-cycles
> >> 2.003146566 <not counted> cpu-cycles
> >> 3.005073317 <not counted> cpu-cycles
> >> 4.006337062 <not counted> cpu-cycles
> >> Events enabled
> >> enable acked(ack)
> >> 5.011182000 54,128,692 cpu-cycles <===
> >> 6.012300167 3,648,804,827 cpu-cycles
> >> 7.013631689 590,438,536 cpu-cycles
> >> 8.015558583 406,935,663 cpu-cycles
> >> 9.017455505 407,806,862 cpu-cycles
> >> 10.019300780 399,351,824 cpu-cycles
> >> 11.021180025 404,584,417 cpu-cycles
> >> 12.023033661 537,787,981 cpu-cycles
> >> 13.024422354 699,395,364 cpu-cycles
> >> 14.026325749 397,871,324 cpu-cycles
> >> disable acked()
> >> Events disabled
> >> 15.027857981 396,956,159 cpu-cycles <===
> >> 16.029279264 <not counted> cpu-cycles
> >> 17.031131311 <not counted> cpu-cycles
> >> 18.033010580 <not counted> cpu-cycles
> >> 19.034918883 <not counted> cpu-cycles
> >> enable acked(ack)
> >> Events enabled
> >> 20.036758793 183,544,975 cpu-cycles <===
> >> 21.038163289 419,054,544 cpu-cycles
> >> 22.040108245 413,993,309 cpu-cycles
> >> 23.042042365 403,584,493 cpu-cycles
> >> 24.043985381 416,512,094 cpu-cycles
> >> 25.045925682 401,513,429 cpu-cycles
> >> # time counts unit events
> >> 26.047822238 461,205,096 cpu-cycles
> >> 27.049784263 414,319,162 cpu-cycles
> >> 28.051745360 403,706,915 cpu-cycles
> >> 29.053674600 416,502,883 cpu-cycles
> >> disable acked()
> >> Events disabled
> >> 30.054750685 414,184,409 cpu-cycles <===
> >
> > ok, but we could still take handle_interval out of process_evlist
> > and the interval process will be more clear for me (with some
> > additional comments in the code) ... perhaps something like below?
> >
> > thanks,
> > jirka
> >
> >
> > ---
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index 5021f7286422..af83bf6b2db0 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -485,19 +485,18 @@ static bool handle_interval(unsigned int interval, int *times)
> > return false;
> > }
> >
> > -static bool process_evlist(struct evlist *evlist, unsigned int interval, int *times)
> > +static bool process_evlist(struct evlist *evlist)
> > {
> > - bool stop = false;
> > enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
> > + bool enabled = false;
> >
> > if (evlist__ctlfd_process(evlist, &cmd) > 0) {
> > switch (cmd) {
> > case EVLIST_CTL_CMD_ENABLE:
> > pr_info(EVLIST_ENABLED_MSG);
> > - stop = handle_interval(interval, times);
> > + enabled = true;
> > break;
> > case EVLIST_CTL_CMD_DISABLE:
> > - stop = handle_interval(interval, times);
> > pr_info(EVLIST_DISABLED_MSG);
> > break;
> > case EVLIST_CTL_CMD_ACK:
> > @@ -507,7 +506,7 @@ static bool process_evlist(struct evlist *evlist, unsigned int interval, int *ti
> > }
> > }
> >
> > - return stop;
> > + return enabled;
> > }
> >
> > static void enable_counters(void)
> > @@ -618,7 +617,8 @@ static int dispatch_events(bool forks, int timeout, int interval, int *times)
> > stop = handle_interval(interval, times);
> > time_to_sleep = sleep_time;
> > } else { /* fd revent */
> > - stop = process_evlist(evsel_list, interval, times);
> > + if (process_evlist(evsel_list))
> > + stop = handle_interval(interval, times);
>
> It will call only on enable command and lead to artificial spikes in the beginning of interval.
> May be just take handle_interval() out of process_evlist() and have it similar to record case?
it can be called also for disable case then
jirka
next prev parent reply other threads:[~2020-07-07 13:14 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-03 7:38 [PATCH v9 00/15] perf: support enable and disable commands in stat and record modes Alexey Budankov
2020-07-03 7:41 ` [PATCH v9 01/15] tools/libperf: avoid fds moving by fdarray__filter() Alexey Budankov
2020-07-03 7:41 ` [PATCH v9 02/15] tools/libperf: add properties to struct pollfd *entries objects Alexey Budankov
2020-07-06 12:24 ` Jiri Olsa
2020-07-06 13:05 ` Alexey Budankov
2020-07-03 7:42 ` [PATCH v9 03/15] tools/libperf: don't count nonfilterable fds by fdarray__filter() Alexey Budankov
2020-07-03 7:43 ` [PATCH v9 04/15] perf evlist: introduce control file descriptors Alexey Budankov
2020-07-03 7:43 ` [PATCH v9 05/15] perf evlist: implement control command handling functions Alexey Budankov
2020-07-03 7:44 ` [PATCH v9 06/15] perf stat: factor out body of event handling loop for system wide Alexey Budankov
2020-07-03 7:45 ` [PATCH v9 07/15] perf stat: move target check to loop control statement Alexey Budankov
2020-07-03 7:45 ` [PATCH v9 08/15] perf stat: factor out body of event handling loop for fork case Alexey Budankov
2020-07-03 7:46 ` [PATCH v9 09/15] perf stat: factor out event handling loop into dispatch_events() Alexey Budankov
2020-07-06 12:27 ` Jiri Olsa
2020-07-06 13:07 ` Alexey Budankov
2020-07-03 7:46 ` [PATCH v9 10/15] perf stat: extend -D,--delay option with -1 value Alexey Budankov
2020-07-03 7:47 ` [PATCH v9 11/15] perf stat: implement control commands handling Alexey Budankov
2020-07-06 12:34 ` Jiri Olsa
2020-07-06 14:47 ` Alexey Budankov
2020-07-06 19:34 ` Jiri Olsa
2020-07-07 13:07 ` Alexey Budankov
2020-07-07 13:14 ` Jiri Olsa [this message]
2020-07-07 13:24 ` Alexey Budankov
2020-07-07 14:23 ` Jiri Olsa
2020-07-07 14:55 ` Alexey Budankov
2020-07-07 16:05 ` Jiri Olsa
2020-07-07 16:43 ` Alexey Budankov
2020-07-07 17:19 ` Alexey Budankov
2020-07-06 12:37 ` Jiri Olsa
2020-07-06 13:10 ` Alexey Budankov
2020-07-03 7:47 ` [PATCH v9 12/15] perf stat: introduce --control fd:ctl-fd[,ack-fd] options Alexey Budankov
2020-07-03 7:48 ` [PATCH v9 13/15] perf record: extend -D,--delay option with -1 value Alexey Budankov
2020-07-03 7:49 ` [PATCH v9 14/15] perf record: implement control commands handling Alexey Budankov
2020-07-03 7:49 ` [PATCH v9 15/15] perf record: introduce --control fd:ctl-fd[,ack-fd] options Alexey Budankov
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