Re: [PATCHv2 4/5] perf stat: Add -a as a default target

From: Arnaldo Carvalho de Melo
Date: Mon Feb 20 2017 - 16:23:27 EST

Em Mon, Feb 20, 2017 at 09:31:49PM +0100, Borislav Petkov escreveu:
> Btw, I received your mail just now - probably greylisting...
> On Mon, Feb 20, 2017 at 10:44:33AM -0300, Arnaldo Carvalho de Melo wrote:
> > Isn't this confusing, i.e. people runnin 'tool workload' can be lead to
> > think that the events reported took place just when the workload was
> > running, i.e. on the same cpu and while it was being scheduled?
> That's a good point.
> > I understand the desire to avoid asking people to use -a, i.e. if it
> > only makes sense as system wide, hey, do it as system wide, but can't
> > this be confusing?
> Well, I did
> tool workload
> and it said <not supported>. Now, if I'm the only one to stare puzzled

Well, this one should be read (and written in the tool output as):

<not supported in workload only mode, try system wide, using -a>

> at this and wonder why it says "not supported", then sure, I know now
> that I should use -a.
> But if other users are as confused as me, you probably want to tell them
> to try -a too, no?
> IOW, we probably could extend my other patch which says that people
> should try to disable the HW NMI watchdog to say "try using -a for
> uncore-only events" when it detects <not supported>.

Right, the ENOTSUPP in this case needs to be properly expanded into
something meaningful, as suggested above.

> Thoughts?
> --
> Regards/Gruss,
> Boris.
> Good mailing practices for 400: avoid top-posting and trim the reply.