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

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Date:   Tue, 7 Jul 2020 18:05:24 +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 Tue, Jul 07, 2020 at 05:55:14PM +0300, Alexey Budankov wrote:

SNIP

> process_evlist() now looks suboptimal since record mode code directly calls evlist__ctlfd_process()
> and then handles returned command specifically to the mode. So in v10 I replaced process_evlist()
> call with direct evlist__ctlfd_process() call and then handling the returned command by printing
> command msg tag and counter values in the required order. Like this:
> 
> +		clock_gettime(CLOCK_MONOTONIC, &time_start);
> +		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
> +			if (timeout)
> +				break;
> +			else
> +				stop = handle_interval(interval, times);
> +			time_to_sleep = sleep_time;
> +		} else { /* fd revent */
> +			if (evlist__ctlfd_process(evsel_list, &cmd) > 0) {
> +				if (interval) {
> +					switch (cmd) {
> +					case EVLIST_CTL_CMD_ENABLE:
> +						pr_info(EVLIST_ENABLED_MSG);
> +						process_interval();
> +						break;
> +					case EVLIST_CTL_CMD_DISABLE:
> +						process_interval();
> +						pr_info(EVLIST_DISABLED_MSG);
> +						break;
> +					case EVLIST_CTL_CMD_ACK:
> +					case EVLIST_CTL_CMD_UNSUPPORTED:
> +					default:
> +						break;
> +					}
> +				}
> +			}
> +			clock_gettime(CLOCK_MONOTONIC, &time_stop);
> +			compute_tts(&time_start, &time_stop, &time_to_sleep);
> +		}


hum, why not just get the bool from process_evlist like below?

jirka


---
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 5021f7286422..32dd3de93f35 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -485,20 +485,20 @@ 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 display = 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);
+			display = true;
 			break;
 		case EVLIST_CTL_CMD_DISABLE:
-			stop = handle_interval(interval, times);
 			pr_info(EVLIST_DISABLED_MSG);
+			display = true;
 			break;
 		case EVLIST_CTL_CMD_ACK:
 		case EVLIST_CTL_CMD_UNSUPPORTED:
@@ -507,7 +507,7 @@ static bool process_evlist(struct evlist *evlist, unsigned int interval, int *ti
 		}
 	}
 
-	return stop;
+	return display;
 }
 
 static void enable_counters(void)
@@ -618,7 +618,8 @@ 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);
 			clock_gettime(CLOCK_MONOTONIC, &time_stop);
 			diff_timespec(&time_diff, &time_stop, &time_start);
 			time_to_sleep -= time_diff.tv_sec * MSEC_PER_SEC +