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

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Message-ID: <20200623145442.GE2619137@krava>
Date:   Tue, 23 Jun 2020 16:54:42 +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 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?

jirka