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[Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue noti
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify |
Date: |
Sun, 12 Dec 2010 23:09:59 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sun, Dec 12, 2010 at 10:56:34PM +0200, Michael S. Tsirkin wrote:
> On Sun, Dec 12, 2010 at 10:42:28PM +0200, Michael S. Tsirkin wrote:
> > On Sun, Dec 12, 2010 at 10:41:28PM +0200, Michael S. Tsirkin wrote:
> > > On Sun, Dec 12, 2010 at 03:02:04PM +0000, Stefan Hajnoczi wrote:
> > > > See below for the v5 changelog.
> > > >
> > > > Due to lack of connectivity I am sending from GMail. Git should retain
> > > > my
> > > > address@hidden From address.
> > > >
> > > > Virtqueue notify is currently handled synchronously in userspace
> > > > virtio. This
> > > > prevents the vcpu from executing guest code while hardware emulation
> > > > code
> > > > handles the notify.
> > > >
> > > > On systems that support KVM, the ioeventfd mechanism can be used to make
> > > > virtqueue notify a lightweight exit by deferring hardware emulation to
> > > > the
> > > > iothread and allowing the VM to continue execution. This model is
> > > > similar to
> > > > how vhost receives virtqueue notifies.
> > > >
> > > > The result of this change is improved performance for userspace virtio
> > > > devices.
> > > > Virtio-blk throughput increases especially for multithreaded scenarios
> > > > and
> > > > virtio-net transmit throughput increases substantially.
> > >
> > > Interestingly, I see decreased throughput for small message
> > > host to get netperf runs.
> > >
> > > The command that I used was:
> > > netperf -H $vguest -- -m 200
> > >
> > > And the results are:
> > > - with ioeventfd=off
> > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.104
> > > (11.0.0.104) port 0 AF_INET : demo
> > > Recv Send Send Utilization Service
> > > Demand
> > > Socket Socket Message Elapsed Send Recv Send
> > > Recv
> > > Size Size Size Time Throughput local remote local
> > > remote
> > > bytes bytes bytes secs. 10^6bits/s % S % S us/KB
> > > us/KB
> > >
> > > 87380 16384 200 10.00 3035.48 15.50 99.30 6.695
> > > 2.680
> > >
> > > - with ioeventfd=on
> > > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.104
> > > (11.0.0.104) port 0 AF_INET : demo
> > > Recv Send Send Utilization Service
> > > Demand
> > > Socket Socket Message Elapsed Send Recv Send
> > > Recv
> > > Size Size Size Time Throughput local remote local
> > > remote
> > > bytes bytes bytes secs. 10^6bits/s % S % S us/KB
> > > us/KB
> > >
> > > 87380 16384 200 10.00 1770.95 18.16 51.65 13.442
> > > 2.389
> > >
> > >
> > > Do you see this behaviour too?
> >
> > Just a note: this is with the patchset ported to qemu-kvm.
>
> And just another note: the trend is reversed for larged messages,
> e.g. with 1.5k messages ioeventfd=on outputforms ioeventfd=off.
Another datapoint where I see a regression is with 4000 byte messages
for guest to host traffic.
ioeventfd=off
set_up_server could not establish a listen endpoint for port 12865 with family
AF_UNSPEC
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.4 (11.0.0.4)
port 0 AF_INET : demo
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
87380 16384 4000 10.00 7717.56 98.80 15.11 1.049 2.566
ioeventfd=on
TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.4 (11.0.0.4)
port 0 AF_INET : demo
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
87380 16384 4000 10.00 3965.86 87.69 15.29 1.811 5.055
--
MST
- [Qemu-devel] [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] [PATCH v5 4/4] docs: Document virtio PCI -device ioeventfd=on|off, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] [PATCH v5 1/4] virtio-pci: Rename bugs field to flags, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] [PATCH v5 3/4] virtio-pci: Don't use ioeventfd on old kernels, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] [PATCH v5 2/4] virtio-pci: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/12
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/12
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/12
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/12
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify,
Michael S. Tsirkin <=
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Stefan Hajnoczi, 2010/12/13
- [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue notify, Michael S. Tsirkin, 2010/12/13