linux-kernel - Re: [PATCH v3 0/5] Cavium ThunderX uncore PMU support

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Message-ID: <20161020112351.GC13708@hardcore>
Date:   Thu, 20 Oct 2016 13:23:51 +0200
From:   Jan Glauber <jan.glauber@...iumnetworks.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     Mark Rutland <mark.rutland@....com>,
        Will Deacon <will.deacon@....com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 0/5] Cavium ThunderX uncore PMU support

On Thu, Oct 20, 2016 at 12:37:07PM +0200, Peter Zijlstra wrote:
> On Thu, Oct 20, 2016 at 11:30:36AM +0200, Jan Glauber wrote:
> > Note:
> > I'm using perf_sw_context in difference to perf_invalid_context
> > (see WARN_ON in perf_pmu_register). Reason is that with perf_invalid_context
> > add() is never called and the counter results are shown as "unsupported" by
> > perf. With perf_sw_context everything works as expected.
> 
> What?! All the uncore PMUs use perf_invalid_context. What doesn't work
> for you?

OK, so using perf_invalid_context and "-a" seems to work.

But I must say that I hate that from a user perspective. The user needs to know about
the type of PMU behind the event and then provide "-a" or get a "<not supported"
as counter value?