linux-kernel - Re: [PATCH v8 09/13] perf stat: implement control commands handling

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Message-ID: <20200625121453.GH2719003@krava>
Date:   Thu, 25 Jun 2020 14:14:53 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 09/13] perf stat: implement control commands handling

On Wed, Jun 24, 2020 at 05:10:10PM +0300, Alexey Budankov wrote:
> 
> On 23.06.2020 17:54, Jiri Olsa wrote:
> > On Wed, Jun 17, 2020 at 11:41:30AM +0300, Alexey Budankov wrote:
> > 
> > SNIP
> > 
> >>  
> >>  	while (1) {
> >>  		if (forks)
> >> @@ -581,8 +617,17 @@ static int dispatch_events(bool forks, int timeout, int interval, int *times, st
> >>  		if (done || stop || child)
> >>  			break;
> >>  
> >> -		nanosleep(ts, NULL);
> >> -		stop = process_timeout(timeout, interval, times);
> >> +		clock_gettime(CLOCK_MONOTONIC, &time_start);
> >> +		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
> >> +			stop = process_timeout(timeout, interval, times);
> >> +			time_to_sleep = sleep_time;
> >> +		} else { /* fd revent */
> >> +			stop = process_evlist(evsel_list, interval, times);
> >> +			clock_gettime(CLOCK_MONOTONIC, &time_stop);
> >> +			diff_timespec(&time_diff, &time_stop, &time_start);
> >> +			time_to_sleep -= time_diff.tv_sec * MSEC_PER_SEC +
> >> +					time_diff.tv_nsec / NSEC_PER_MSEC;
> > 
> > should we check time_to_sleep > time_diff first?
> 
> Probably and if time_diff > time_to_sleep then time_to_sleep = 0 ?

or extra call to process_timeout? if we dont want to call evlist_poll
with 0 timeout

jirka

> 
> ~Alexey
> 
> > 
> > jirka
> > 
>