linux-kernel - Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on

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Message-ID: <20170215125128.GB4020@kernel.org>
Date:   Wed, 15 Feb 2017 09:51:28 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc:     Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        vince@...ter.net, eranian@...gle.com,
        Arnaldo Carvalho de Melo <acme@...radead.org>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX
 operation is on

Em Wed, Feb 15, 2017 at 10:34:58AM +0200, Alexander Shishkin escreveu:
> Arnaldo Carvalho de Melo <acme@...nel.org> writes:
> > Em Tue, Feb 14, 2017 at 03:24:16PM +0200, Alexander Shishkin escreveu:
> > Yeah, I saw that as well, and Andi told me about this limitation, so,
> > for quite a while now, everytime I need to test PT on the only machine I
> > have with it, I have to stop my kvm sessions :-\

> > Thanks for working on this!

> Well, we can't make the limitation go away. You'll still have to stop
> kvms to get any 'meaningful' PT data.

If we can't make the limitation go away we need to at least warn users
instead of let 'perf record' sit there doing nothing and then at the end
return as if everything went well only to when trying to use 'perf
script' nothing will appear.

- Arnaldo