* Avi Kivity <avi@xxxxxxxxxx> [2010-12-11 09:31:24]: > On 12/10/2010 07:03 AM, Balbir Singh wrote: > >> > >> Scheduler people, please flame me with anything I may have done > >> wrong, so I can do it right for a next version :) > >> > > > >This is a good problem statement, there are other things to consider > >as well > > > >1. If a hard limit feature is enabled underneath, donating the > >timeslice would probably not make too much sense in that case > > What's the alternative? > > Consider a two vcpu guest with a 50% hard cap. Suppose the workload > involves ping-ponging within the guest. If the scheduler decides to > schedule the vcpus without any overlap, then the throughput will be > dictated by the time slice. If we allow donation, throughput is > limited by context switch latency. > If the vpcu holding the lock runs more and capped, the timeslice transfer is a heuristic that will not help. -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
