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Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores
From: |
Peter Lieven |
Subject: |
Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores |
Date: |
Tue, 6 Nov 2012 08:46:45 +0100 |
User-agent: |
SquirrelMail/1.4.21 |
Dietmar Maurer wrote:
>> > ./x86_64-softmmu/qemu-system-x86_64 -smp sockets=1,cores=2 -m 512 -
>> hda
>> > debian-squeeze-netinst.raw -netdev
>> > type=tap,id=net0,ifname=tap111i0,vhost=on -device
>> > virtio-net-pci,netdev=net0,id=net0
>> >
>> > Downloading a larger file with wget inside the guest will show the
>> problem.
>> Speed drops from 100MB/s to 15MB/s.
>> >
>> > Can someone reproduce that bug? Any ideas how to fix that?
>>
>> Which exact QEMU are you using: qemu or qemu-kvm? Distro package or
>> from source? Any patches applied?
>
> I just tested with latest sources from git://git.qemu-project.org/qemu.git
>
> ./x86_64-softmmu/qemu-system-x86_64 -smp sockets=1,cores=2 -m 512 -hda
> debian-squeeze-netinst.raw -netdev
> type=tap,id=net0,ifname=tap111i0,vhost=on -device
> virtio-net-pci,netdev=net0,id=net0 --enable-kvm
>
> got incredible bad performance - can't you reproduce the problem?
I have seen a similar problem, but it seems to be only with extreme old
guest kernels. With Ubuntu 12.04 it seems not to be there. Can you try a
recent guest kernel.
- [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/05
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Stefan Hajnoczi, 2012/11/05
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/05
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores,
Peter Lieven <=
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Jan Kiszka, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Jan Kiszka, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/06
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Jan Kiszka, 2012/11/08
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Peter Lieven, 2012/11/08
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Dietmar Maurer, 2012/11/08
- Re: [Qemu-devel] slow virtio network with vhost=on and multiple cores, Peter Lieven, 2012/11/08