linux-kernel - Re: [PATCH 2/3] perf, x86: Use GO/HO bits in perf-ctr

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Date:	Tue, 10 May 2011 17:04:12 +0200
From:	"Roedel, Joerg" <Joerg.Roedel@....com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	benh <benh@...nel.crashing.org>,
	Anton Blanchard <anton@...ba.org>, davem <davem@...emloft.net>
Subject: Re: [PATCH 2/3] perf, x86: Use GO/HO bits in perf-ctr

On Tue, May 10, 2011 at 10:48:20AM -0400, Peter Zijlstra wrote:
> On Tue, 2011-05-10 at 16:35 +0200, Joerg Roedel wrote:
> > The AMD perf-counters support counting in guest or host-mode
> > only. Make use of that feature when user-space specified
> > guest/host-mode only counting.
> 
> Subject mentions x86, does Intel have anything similar so you can make
> it work for them too?

Intel does not support guest or host-only counting in the hardware (at
least according to my documentation). If wanted it could be approximated by
enabling/disabling the counters in the guest-entry path.
So subject should better say "perf, amd", right?

> Also, might be nice to ask the power and sparc64 people if their archs
> can also differentiate between guest and host thingies.

Right, I don't know if their hardware has similar features. I'll try to
find this out.

	Joerg


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