Re: VM performance issue in KVM guests.

[Srivatsa Vaddagiri]

On Thu, Apr 15, 2010 at 03:33:18PM +0200, Peter Zijlstra wrote:
> On Thu, 2010-04-15 at 11:18 +0300, Avi Kivity wrote:
> > 
> > Certainly that has even greater potential for Linux guests.  Note that 
> > we spin on mutexes now, so we need to prevent preemption while the lock 
> > owner is running. 
> 
> either that, or disable spinning on (para) virt kernels. Para virt
> kernels could possibly extend the thing by also checking to see if the
> owner's vcpu is running.

I suspect we will need a combination of both approaches, given that we will not
be able to avoid preempting guests in their critical section always (too long
critical sections or real-time tasks wanting to preempt). Other idea is to
gang-schedule VCPUs of the same guest as much as possible?

- vatsa
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