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

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Date:   Tue, 21 Feb 2017 08:54:37 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, David Ahern <dsahern@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCHv2 4/5] perf stat: Add -a as a default target

On Mon, Feb 20, 2017 at 11:47:16PM +0100, Borislav Petkov wrote:
> On Mon, Feb 20, 2017 at 06:22:54PM -0300, Arnaldo Carvalho de Melo wrote:
> > Well, this one should be read (and written in the tool output as):
> > 
> > <not supported in workload only mode, try system wide, using -a>
> 
> Do you want to change that CNTR_NOT_SUPPORTED string unconditionally to
> something like above?
> 
> Because perf_evsel.supported seems like it means that counter is not
> supported but not necessarily only because of the missing -a for an
> uncore event, AFAICT. I could be wrong.
> 
> > Right, the ENOTSUPP in this case needs to be properly expanded into
> > something meaningful, as suggested above.
> 
> I dumped errno in __run_perf_stat():
> 
> ./perf stat -v -e amd_nb/event=0xe0,umask=0x1f/ sleep 1
> Using CPUID AuthenticAMD-21-2
> Warning:
> amd_nb/event=0xe0,umask=0x1f/ event is not supported by the kernel: 22.
> 
> It is -EINVAL and the syscall returns -EINVAL in bunch of places so I'm
> guessing this might not be a good way to match the retval to the proper
> error message.
> 
> Peterz said something about scanning all events supplied by -e and if
> all are uncore, to set -a automatically. Can we do that?

right, so that's different from what we actually did.. ;-)

I'll check on this one.. might not be as straight forward,
because some uncore events might have already cpumask limit

jirka