Re: KVM call agenda for Feb 9

Avi Kivity
2010-02-09T06:56:26Z

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
- rcuify/fine-grain qemu locks

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.