From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Zhang Haoyu <zhanghy@sangfor.com>,
Amit Shah <amit.shah@redhat.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] [question] virtio-blk performance degradationhappened with virito-serial
Date: Mon, 01 Sep 2014 16:03:57 +0200 [thread overview]
Message-ID: <54047CCD.4000101@de.ibm.com> (raw)
In-Reply-To: <5404749F.7050606@redhat.com>
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.
Christian
next prev parent reply other threads:[~2014-09-01 14:04 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-29 7:45 [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial Zhang Haoyu
2014-08-29 14:38 ` Amit Shah
2014-09-01 12:38 ` [Qemu-devel] [question] virtio-blk performance degradationhappened " Zhang Haoyu
2014-09-01 12:46 ` Amit Shah
2014-09-01 12:57 ` [Qemu-devel] [question] virtio-blk performancedegradationhappened " Zhang Haoyu
2014-09-01 12:52 ` [Qemu-devel] [question] virtio-blk performance degradationhappened " Zhang Haoyu
2014-09-01 13:09 ` Christian Borntraeger
2014-09-01 13:12 ` Paolo Bonzini
2014-09-01 13:22 ` Christian Borntraeger
2014-09-01 13:29 ` Paolo Bonzini
2014-09-01 14:03 ` Christian Borntraeger [this message]
2014-09-01 14:15 ` Christian Borntraeger
2014-09-04 7:56 ` [Qemu-devel] [question] virtio-blk performance degradationhappenedwith virito-serial Zhang Haoyu
2014-09-07 9:46 ` Zhang Haoyu
2014-09-11 6:11 ` Amit Shah
2014-09-12 3:21 ` [Qemu-devel] [question] virtio-blk performance degradation happened with virito-serial Zhang Haoyu
2014-09-12 12:38 ` Stefan Hajnoczi
2014-09-13 17:22 ` Max Reitz
2014-09-16 14:59 ` Zhang Haoyu
2014-09-02 6:36 ` [Qemu-devel] [question] virtio-blk performance degradationhappened " Amit Shah
2014-09-02 18:05 ` Andrey Korolyov
2014-09-02 18:11 ` Amit Shah
2014-09-02 18:27 ` Andrey Korolyov
2014-09-04 2:20 ` [Qemu-devel] [question] virtio-blk performancedegradationhappened " Zhang Haoyu
2014-09-19 5:53 ` [Qemu-devel] [question] virtio-blk performance degradationhappened " Fam Zheng
2014-09-19 13:35 ` Paolo Bonzini
2014-09-22 13:23 ` [Qemu-devel] [question] virtio-blk performancedegradationhappened " Zhang Haoyu
2014-09-23 1:29 ` Fam Zheng
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