linux-kernel - Re: Hardware performance events are not counted by "perf" in a 2.6.31.12 KVM guest

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Message-ID: <20100328115758.GP14800@8bytes.org>
Date:	Sun, 28 Mar 2010 13:57:58 +0200
From:	Joerg Roedel <joro@...tes.org>
To:	Naresh Rapolu <nrapolu@...due.edu>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Hardware performance events are not counted by  "perf"   in a
	2.6.31.12 KVM guest

On Fri, Mar 26, 2010 at 10:03:10PM -0400, Naresh Rapolu wrote:
> "perf"  tool does not count  hardware performance events ( cache misses  
> etc) in a  KVM guest ( Ubuntu 9.10 karmic,  2.6.31-14-generic  kernel)  
> on  Xeon 5530 quad-core.  The host  is  2.6.28  kernel , Ubuntu 8.04  
> LTS, Hardy.

The KVM guest has no access to the hardware counters of the cpu. KVM
ignores these accesses from guests. Making this work needs proper
virtualization of the PMU which is not implemented yet.

Regards,

	Joerg

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