On 04/12/2011 07:45 PM, Scott Wood wrote:
On Tue, 12 Apr 2011 16:05:29 +0000 Bhushan Bharat-R65777<R65777@xxxxxxxxxxxxx> wrote: > > > > -----Original Message----- > > From: Avi Kivity [mailto:avi@xxxxxxxxxx] > > Sent: Tuesday, April 12, 2011 8:09 PM > > To: Bhushan Bharat-R65777 > > Cc: kvm@xxxxxxxxxxxxxxx; bharatb.yadav@xxxxxxxxx > > 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.
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