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Tue, 7 Jul 2020 13:14:11 +0000 (UTC) Received: from krava (unknown [10.40.195.209]) by smtp.corp.redhat.com (Postfix) with SMTP id 793F77742D; Tue, 7 Jul 2020 13:14:04 +0000 (UTC) Date: Tue, 7 Jul 2020 15:14:03 +0200 From: Jiri Olsa To: Alexey Budankov Cc: Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Peter Zijlstra , Ingo Molnar , Andi Kleen , linux-kernel Subject: Re: [PATCH v9 11/15] perf stat: implement control commands handling Message-ID: <20200707131403.GD3424581@krava> References: <21669f5a-6220-df0a-09f1-b73b32487f23@linux.intel.com> <20200706123436.GD3401866@krava> <6cf91811-ea6a-3c7c-8bbf-7f96bfa1fc82@linux.intel.com> <20200706193418.GB3424581@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > >>>> --- > >>>> 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 cpu-cycles > >> 2.003146566 cpu-cycles > >> 3.005073317 cpu-cycles > >> 4.006337062 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 cpu-cycles > >> 17.031131311 cpu-cycles > >> 18.033010580 cpu-cycles > >> 19.034918883 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