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Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm
From: |
Rusty Russell |
Subject: |
Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm |
Date: |
Wed, 22 Feb 2012 08:46:41 +1030 |
User-agent: |
Notmuch/0.6.1-1 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) |
On Tue, 21 Feb 2012 17:45:08 +0100, Dongsu Park <address@hidden> wrote:
> Hi Rusty,
>
> On 13.02.2012 10:25, Rusty Russell wrote:
> > On Fri, 10 Feb 2012 15:36:39 +0100, Dongsu Park <address@hidden> wrote:
> > > Hi,
> > >
> > > Recently I observed performance regression regarding virtio-blk,
> > > especially different IO bandwidths between qemu-kvm 0.14.1 and 1.0.
> > > So I want to share the benchmark results, and ask you what the reason
> > > would be.
> >
> > Interesting. There are two obvious possibilities here. One is that
> > qemu has regressed, the other is that virtio_blk has regressed; the new
> > qemu may negotiate new features. Please do the following in the guest
> > with old and new qemus:
> >
> > cat /sys/class/block/vdb/device/features
> >
> > (eg, here that gives: 0010101101100000000000000000100e0).
>
> I did that on guest VM, using both qemu-kvm 0.14.1 and 1.0.
> (cat /sys/class/block/vdb/device/features)
>
> using qemu-kvm 0.14.1:
>
> 0010101101100000000000000000100000000000000000000000000000000000
>
> using qemu-kvm 1.0:
>
> 0010101101100000000000000000110000000000000000000000000000000000
>
> >From my understanding, both of them have the same virtio features.
> Please correct me if I'm wrong.
Well, 1.0 supports event index (feature 29), but that's the only
difference.
This seems very much like a qemu regression.
Thanks,
Rusty.
- [Qemu-devel] virtio-blk performance regression and qemu-kvm, Dongsu Park, 2012/02/10
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Rusty Russell, 2012/02/12
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Stefan Hajnoczi, 2012/02/13
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Dongsu Park, 2012/02/21
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Stefan Hajnoczi, 2012/02/21
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Dongsu Park, 2012/02/22
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Stefan Hajnoczi, 2012/02/22
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Martin Mailand, 2012/02/28
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Stefan Hajnoczi, 2012/02/28
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Martin Mailand, 2012/02/28
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Stefan Hajnoczi, 2012/02/29
- Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm, Martin Mailand, 2012/02/29