linux-kernel - Re: [PATCH v4 04/10] perf stat: factor out event handling loop into a function

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Date:   Mon, 1 Jun 2020 10:38:49 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.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 v4 04/10] perf stat: factor out event handling loop into a
 function


On 31.05.2020 21:19, Jiri Olsa wrote:
> On Mon, May 25, 2020 at 05:19:45PM +0300, Alexey Budankov wrote:
> 
> SNIP
> 
>> @@ -544,12 +598,10 @@ static enum counter_recovery stat_handle_error(struct evsel *counter)
>>  static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>  {
>>  	int interval = stat_config.interval;
>> -	int times = stat_config.times;
>>  	int timeout = stat_config.timeout;
>>  	char msg[BUFSIZ];
>>  	unsigned long long t0, t1;
>>  	struct evsel *counter;
>> -	struct timespec ts;
>>  	size_t l;
>>  	int status = 0;
>>  	const bool forks = (argc > 0);
>> @@ -558,17 +610,6 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>  	int i, cpu;
>>  	bool second_pass = false;
>>  
>> -	if (interval) {
>> -		ts.tv_sec  = interval / USEC_PER_MSEC;
>> -		ts.tv_nsec = (interval % USEC_PER_MSEC) * NSEC_PER_MSEC;
>> -	} else if (timeout) {
>> -		ts.tv_sec  = timeout / USEC_PER_MSEC;
>> -		ts.tv_nsec = (timeout % USEC_PER_MSEC) * NSEC_PER_MSEC;
>> -	} else {
>> -		ts.tv_sec  = 1;
>> -		ts.tv_nsec = 0;
>> -	}
>> -
>>  	if (forks) {
>>  		if (perf_evlist__prepare_workload(evsel_list, &target, argv, is_pipe,
>>  						  workload_exec_failed_signal) < 0) {
>> @@ -725,16 +766,9 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>  		perf_evlist__start_workload(evsel_list);
>>  		enable_counters();
>>  
>> -		if (interval || timeout) {
>> -			while (!waitpid(child_pid, &status, WNOHANG)) {
>> -				nanosleep(&ts, NULL);
>> -				if (timeout)
>> -					break;
>> -				process_interval();
>> -				if (interval_count && !(--times))
>> -					break;
>> -			}
>> -		}
>> +		if (interval || timeout)
>> +			dispatch_events(child_pid, &stat_config);
>> +
>>  		if (child_pid != -1) {
>>  			if (timeout)
>>  				kill(child_pid, SIGTERM);
>> @@ -751,18 +785,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>  			psignal(WTERMSIG(status), argv[0]);
>>  	} else {
>>  		enable_counters();
>> -		while (!done) {
>> -			nanosleep(&ts, NULL);
>> -			if (!is_target_alive(&target, evsel_list->core.threads))
>> -				break;
>> -			if (timeout)
>> -				break;
>> -			if (interval) {
>> -				process_interval();
>> -				if (interval_count && !(--times))
>> -					break;
>> -			}
>> -		}
>> +		dispatch_events(-1, &stat_config);
> 
> hum, from the discussion we had on v3  I expected more smaller patches
> with easy changes, so the change is more transparent and easy to review
> 
> as I said before this part really makes me worried and needs to be as clear
> as possible.. please introdce the new function first and replace the factored
> places separately, also more verbose changelog would help ;-)

Ok. Will try to reshape the patch that way.

~Alexey