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Date: Wed, 24 Jan 2018 08:12:33 +0800 From: "Jin, Yao" <yao.jin@...ux.intel.com> To: Jiri Olsa <jolsa@...hat.com> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>, Arnaldo Carvalho de Melo <acme@...nel.org>, jolsa@...nel.org, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>, kan.liang@...el.com, yao.jin@...el.com Subject: Re: [PATCH] perf util: Use target->per_thread and target->system_wide flags On 1/23/2018 10:40 PM, Jiri Olsa wrote: > On Tue, Jan 23, 2018 at 07:02:44AM +0800, Jin, Yao wrote: > > SNIP > >>>> threads = thread_map__new_str(target->pid, target->tid, target->uid, >>>> - target->per_thread); >>>> + target->per_thread && target->system_wide); >>> >>> At first glance I thought your solution would do the trick but perf >>> record does use target->system_wide when the '-a' switch is used. >>> Moreover specifying the '-a' switch doesn't prevent the '--per-thread' >>> option from being used as well, making both target->perf_thread and >>> target_system_wide equal to true (and that is not good). >>> >>> Although not a fan of adding more to struct target, the advantage of >>> having target->all_threads is that we are guaranteed that it isn't >>> used anywhere else. >>> >>> Let me know what you think, >>> Mathieu >>> >> >> If we specify both '-a' and '--per-thread' to perf record, perf record will >> override'--per-thread'. So now target->per_thread = false, and >> target->system_wide = true. >> >> If we specify '--per-thread' only to perf record, target->per_thread = true, >> and target->system_wide = false. >> >> So whatever for any case, target->per_thread && target->system_wide is >> false. >> >> Since the parameter is false, in thread_map__new_str(), it will not execute >> the thread_map__new_all_cpus(). So that will not change perf record previous >> behavior. >> >> In perf stat, it allows the case that target->per_thread and >> target->system_wide are all true. That means we want to collect system-wide >> per-thread metrics. > > could you please put this description into comment > before the thread_map__new_str is called? > > thanks, > jirka > OK, I will put this comment in v2. I will send v2 soon. Thanks Jin Yao
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