On 09.02.2010, at 07:56, Avi Kivity wrote: > On 02/09/2010 03:28 AM, Chris Wright wrote: >> Please send in any agenda items you are interested in covering. >> > > hpet overhead on large smp guests > > I measured hpet consuming about a half a core's worth of cpu on an idle > Windows 2008 R2 64-way guest. This is mostly due to futex contention, likely > from the qemu mutex. > > Options: > - ignore, this is about 1% of the entire system (but overhead might increase > greatly if a workload triggers more hpet accesses) > - push hpet into kernel, with virtio-net, virtio-blk, and kernel-hpet, > there's little reason to exit into qemu
That sounds like a good idea to me. It'd make the hpet en par with the lapic as timing source concerning overhead. > - rcuify/fine-grain qemu locks And this should be done either way, but is probably not a short-term goal. Alex
