Re: [PATCH] qemu-kvm: response to SIGUSR1 to start/stop a VCPU (v2)

Chris Wright
2010-12-01T17:47:44Z

* Peter Zijlstra (a.p.zijlstra@chello.nl) wrote:
> On Wed, 2010-12-01 at 09:17 -0800, Chris Wright wrote:
> > Directed yield and fairness don't mix well either. You can end up
> > feeding the other tasks more time than you'll ever get back.
>
> If the directed yield is always to another task in your cgroup then
> inter-guest scheduling fairness should be maintained.
>
> Yes, but not the inter-vcpu fairness.

That same vcpu doesn't get fair scheduling if it spends its entire
timeslice spinning on a lock held by a de-scheduled vcpu.