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Re: [Qemu-devel] [question] virtio-blk performance degradationhappened w
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial |
Date: |
Mon, 01 Sep 2014 16:15:54 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.0 |
On 01/09/14 16:03, Christian Borntraeger wrote:
> On 01/09/14 15:29, Paolo Bonzini wrote:
>> Il 01/09/2014 15:22, Christian Borntraeger ha scritto:
>>>>> If virtio-blk and virtio-serial share an IRQ, the guest operating system
>>>>> has to check each virtqueue for activity. Maybe there is some
>>>>> inefficiency doing that.
>>>>> AFAIK virtio-serial registers 64 virtqueues (on 31 ports + console) even
>>>>> if everything is unused.
>>>>
>>>> That could be the case if MSI is disabled.
>>>
>>> Do the windows virtio drivers enable MSIs, in their inf file?
>>
>> It depends on the version of the drivers, but it is a reasonable guess
>> at what differs between Linux and Windows. Haoyu, can you give us the
>> output of lspci from a Linux guest?
>>
>> Paolo
>
> Zhang Haoyu, which virtio drivers did you use?
>
> I just checked the Fedora virtio driver. The INF file does not contain the
> MSI enablement as described in
> http://msdn.microsoft.com/en-us/library/windows/hardware/ff544246%28v=vs.85%29.aspx
> That would explain the performance issues - given that the link information
> is still true.
Sorry, looked at the wrong inf file. The fedora driver does use MSI for serial
and block.
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial, Zhang Haoyu, 2014/09/01
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial, Amit Shah, 2014/09/01
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial, Zhang Haoyu, 2014/09/01
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappenedwith virito-serial, Zhang Haoyu, 2014/09/04
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappenedwith virito-serial, Zhang Haoyu, 2014/09/07
- Re: [Qemu-devel] [question] virtio-blk performance degradationhappenedwith virito-serial, Amit Shah, 2014/09/11
- Re: [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial, Zhang Haoyu, 2014/09/11
- Re: [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial, Stefan Hajnoczi, 2014/09/12
- Re: [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial, Max Reitz, 2014/09/13
- Re: [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial, Zhang Haoyu, 2014/09/16
Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial, Amit Shah, 2014/09/02