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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 22:41:29 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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?
--
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 <=
- [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, 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