Re: [Proposal] QEMU-KVM Interface for granting Performance Monitor to guests

[Avi Kivity <avi@redhat.com>]

On 04/12/2011 07:45 PM, Scott Wood wrote:
> On Tue, 12 Apr 2011 16:05:29 +0000
> Bhushan Bharat-R65777<R65777@freescale.com>  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