linux-kernel - Re: [PATCH 1/2] perf sched: Prefer sched

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Date:   Fri, 7 Aug 2020 13:50:47 -0600
From:   David Ahern <dsahern@...il.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        David Ahern <dsahern@...nel.org>
Cc:     namhyung@...nel.org, linux-kernel@...r.kernel.org, jolsa@...nel.org
Subject: Re: [PATCH 1/2] perf sched: Prefer sched_waking event when it exists

On 8/7/20 1:43 PM, Arnaldo Carvalho de Melo wrote:
>> @@ -2958,9 +2967,10 @@ static int timehist_check_attr(struct perf_sched *sched,
>>  
>>  static int perf_sched__timehist(struct perf_sched *sched)
>>  {
>> -	const struct evsel_str_handler handlers[] = {
>> +	struct evsel_str_handler handlers[] = {
>>  		{ "sched:sched_switch",       timehist_sched_switch_event, },
>>  		{ "sched:sched_wakeup",	      timehist_sched_wakeup_event, },
>> +		{ "sched:sched_waking",       timehist_sched_wakeup_event, },
>>  		{ "sched:sched_wakeup_new",   timehist_sched_wakeup_event, },
>>  	};
>>  	const struct evsel_str_handler migrate_handlers[] = {
>> @@ -3018,6 +3028,11 @@ static int perf_sched__timehist(struct perf_sched *sched)
>>  
>>  	setup_pager();
>>  
>> +	/* prefer sched_waking if it is captured */
>> +	if (perf_evlist__find_tracepoint_by_name(session->evlist,
>> +						  "sched:sched_waking"))
>> +		handlers[1].handler = timehist_sched_wakeup_ignore;
>> +
> 
> 
> ouch, can't we figure out if its present and then don't ask for the
> wakeup one to be recorded?
> 

This is the analysis side. If someone recorded with sched:* we do not
want to analyze both sched_wakeup and sched_waking. Rather, it should
prefer the latter and ignore the former.