linux-kernel - Re: [RFC PATCH] perf: honoring cpuid for number of fixed counters

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Message-ID: <20150604114917.GI3644@twins.programming.kicks-ass.net>
Date:	Thu, 4 Jun 2015 13:49:17 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Imre Palik <imrep.amz@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org, "Palik, Imre" <imrep@...zon.de>,
	Anthony Liguori <aliguori@...zon.com>
Subject: Re: [RFC PATCH] perf: honoring cpuid for number of fixed counters

On Thu, Jun 04, 2015 at 12:35:08PM +0200, Imre Palik wrote:
> On 06/03/15 10:36, Peter Zijlstra wrote:
> > Further, the Intel Arch PerfMon v2 spec actually specifies there to be 3
> > fixed function counters.
> > 
> > So anything that says it is v2+ and does not have the 3, is non
> > compliant.
> >
> > I would suggest you go fix your hypervisor.
> 
> If I set up the hypervisor to advertise Arch PerfMon v1 (0 fixed
> counters), then  without my patch, perf still tries to use fixed
> counters.  So something is clearly broken here.

So the code you deleted does if (version > 1), and last I checked that
should return false if version == 1.

So please check what's happening there first.
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