Re: [PATCH] perf util: Use target->per_thread and target->system_wide flags

[Jin, Yao]

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