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Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] virtio-blk performance regression and qemu-kvm |
Date: |
Wed, 22 Feb 2012 19:53:19 +0000 |
On Wed, Feb 22, 2012 at 4:48 PM, Dongsu Park
<address@hidden> wrote:
>> Try turning ioeventfd off for the virtio-blk device:
>>
>> -device virtio-blk-pci,ioeventfd=off,...
>>
>> You might see better performance since ramdisk I/O should be very
>> low-latency. The overhead of using ioeventfd might not make it
>> worthwhile. The ioeventfd feature was added post-0.14 IIRC. Normally
>> it helps avoid stealing vcpu time and also causing lock contention
>> inside the guest - but if host I/O latency is extremely low it might
>> be faster to issue I/O from the vcpu thread.
>
> Thanks for the tip. I tried that too, but no success.
My guesses have all been wrong. Maybe it's time to git bisect this instead :).
Stefan
- [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 <=
- 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
- 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, Stefan Hajnoczi, 2012/02/29