Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-12-06 Thread Avi Kivity
On 12/01/2010 11:34 PM, Stefan Hajnoczi wrote: >> 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 >> breathing space. > > Thanks f

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-12-01 Thread Stefan Hajnoczi
On Wed, Dec 1, 2010 at 12:30 PM, Avi Kivity wrote: > On 12/01/2010 01:44 PM, Stefan Hajnoczi wrote: >> >> >> >> >>  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

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-12-01 Thread Avi Kivity
On 12/01/2010 01:44 PM, Stefan Hajnoczi wrote: >> >> 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): http://wiki.qemu.org/Features/VirtioIoeventfd The host CPU utilization i

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-12-01 Thread Stefan Hajnoczi
On Mon, Nov 15, 2010 at 11:20 AM, Stefan Hajnoczi wrote: > On Sun, Nov 14, 2010 at 12:19 PM, Avi Kivity 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 thr

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-15 Thread Stefan Hajnoczi
On Sun, Nov 14, 2010 at 12:19 PM, Avi Kivity 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 a

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-14 Thread Avi Kivity
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.

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-14 Thread Avi Kivity
On 11/14/2010 12:37 PM, Stefan Hajnoczi wrote: On Sun, Nov 14, 2010 at 10:34 AM, Avi Kivity wrote: > On 11/12/2010 11:20 AM, Stefan Hajnoczi wrote: >> >> >Who guarantees that less common virtio-blk and virtio-net guest drivers >> >for non-Linux OSes are fine with it? Maybe you should

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-14 Thread Stefan Hajnoczi
On Sun, Nov 14, 2010 at 10:34 AM, Avi Kivity wrote: > On 11/12/2010 11:20 AM, Stefan Hajnoczi wrote: >> >> >  Who guarantees that less common virtio-blk and virtio-net guest drivers >> >  for non-Linux OSes are fine with it?  Maybe you should add a feature >> > flag >> >  that the guest has to ACK

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-14 Thread Avi Kivity
On 11/12/2010 11:20 AM, Stefan Hajnoczi wrote: > Who guarantees that less common virtio-blk and virtio-net guest drivers > for non-Linux OSes are fine with it? Maybe you should add a feature flag > that the guest has to ACK to enable it. Virtio-blk and virtio-net are fine. Both of those dev

Re: [Qemu-devel] Re: [PATCH 2/3] virtio-pci: Use ioeventfd for virtqueue notify

2010-11-12 Thread Stefan Hajnoczi
On Thu, Nov 11, 2010 at 4:45 PM, Christoph Hellwig wrote: > On Thu, Nov 11, 2010 at 01:47:21PM +, Stefan Hajnoczi wrote: >> Some virtio devices are known to have guest drivers which expect a notify to >> be >> processed synchronously and spin waiting for completion.  Only enable >> ioeventfd