From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Proposal] QEMU-KVM Interface for granting Performance Monitor to guests Date: Tue, 12 Apr 2011 19:47:32 +0300 Message-ID: <4DA48224.7040509@redhat.com> References: <4DA46405.2050308@redhat.com> <20110412114538.46e3455d@schlenkerla.am.freescale.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Bhushan Bharat-R65777 , "kvm@vger.kernel.org" , "bharatb.yadav@gmail.com" To: Scott Wood Return-path: Received: from mx1.redhat.com ([209.132.183.28]:29934 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754684Ab1DLQri (ORCPT ); Tue, 12 Apr 2011 12:47:38 -0400 In-Reply-To: <20110412114538.46e3455d@schlenkerla.am.freescale.net> Sender: kvm-owner@vger.kernel.org List-ID: On 04/12/2011 07:45 PM, Scott Wood wrote: > On Tue, 12 Apr 2011 16:05:29 +0000 > Bhushan Bharat-R65777 wrote: > > > > > > > > -----Original Message----- > > > From: Avi Kivity [mailto:avi@redhat.com] > > > Sent: Tuesday, April 12, 2011 8:09 PM > > > To: Bhushan Bharat-R65777 > > > Cc: kvm@vger.kernel.org; bharatb.yadav@gmail.com > > > Subject: Re: [Proposal] QEMU-KVM Interface for granting Performance > > > Monitor to guests > > > > > > On 04/12/2011 10:29 AM, Bhushan Bharat-R65777 wrote: > > > > Hi All, > > > > > > > > The proposal is to about defining the qemu-kvm interface for reserving > > > the performance monitor for guest(guests) in Embedded Power Architecture. > > > The plan is to reserve the Performance Monitor for guest/s on guest boot- > > > up and will be released only on guest reset/exit. If a Performance > > > Monitor reserved by host then it can't be reserved for guest and vice- > > > versa. So when Performance monitor is reserved by host then performance > > > monitor can't be used by guests and if reserved by guest then it should > > > not be used by host. > > > > > > In general we greatly prefer sharing vs. reservation (there are > > > exceptions, for example PCI device assignment). > > > > > > Is there a compelling reason to assign the performance monitor to a > > > single guest? > > > > No, Guest can share with other guests but not with host. > > Note that the reservation system is already in use in the host kernel, > between perf event and oprofile (and I think between users of oprofile). > > Maybe something could be done with KVM acting as a perf event client. > That is the plan for x86 - using perf events to provide a virtual PMU to the guest. -- error compiling committee.c: too many arguments to function