On Mon, 2013-04-22 at 22:44 +0200, Peter Zijlstra wrote: > On Mon, 2013-04-22 at 16:32 -0400, Rik van Riel wrote: > > > > IIRC one of the reasons was that the performance improvement wasn't > > as obvious. Rescheduling VCPUs takes a fair amount of time, quite > > probably more than the typical hold time of a spinlock. > > IIRC it would spin for a while before blocking.. > > /me goes re-read some of that thread... > > Ah, its because PLE is curing most of it.. !PLE it had huge gains but > apparently nobody cares about !PLE hardware anymore :-)
Hmm.. it looked like under light overcommit the paravirt ticket lock still had some gain (~10%) and of course it brings the fairness thing which is always good. I can only imagine the mess unfair + vcpu preemption can bring to guest tasks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
