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Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue
Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify
Wed, 1 Dec 2010 11:44:10 +0000
On Mon, Nov 15, 2010 at 11:20 AM, Stefan Hajnoczi <address@hidden> wrote:
> On Sun, Nov 14, 2010 at 12:19 PM, Avi Kivity <address@hidden> wrote:
>> On 11/14/2010 01:05 PM, Avi Kivity wrote:
>>>> I agree, but let's enable virtio-ioeventfd carefully because bad code
>>>> is out there.
>>> Sure. Note as long as the thread waiting on ioeventfd doesn't consume too
>>> much cpu, it will awaken quickly and we won't have the "transaction per
>>> timeslice" effect.
>>> btw, what about virtio-blk with linux-aio? Have you benchmarked that with
>>> and without ioeventfd?
>> And, what about efficiency? As in bits/cycle?
> We are running benchmarks with this latest patch and will report results.
Full results here (thanks to Khoa Huynh):
The host CPU utilization is scaled to 16 CPUs so a 2-3% reduction is
actually in the 32-48% range for a single CPU.
The guest CPU utilization numbers include an efficiency metric: %vcpu
per MB/sec. Here we see significant improvements too. Guests that
previously couldn't get more CPU work done now have regained some
- Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify,
Stefan Hajnoczi <=