linux-kernel - Re: [PATCH v9 11/15] perf stat: implement control commands handling

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Message-ID: <20200706123436.GD3401866@krava>
Date:   Mon, 6 Jul 2020 14:34:36 +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 v9 11/15] perf stat: implement control commands handling

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@...ux.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?

thanks,
jirka