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Date: Thu, 09 Aug 2012 16:35:27 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] virtio-scsi vs. virtio-blk
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To: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel <qemu-devel@nongnu.org>, ronnie sahlberg <ronniesahlberg@gmail.com>

Il 09/08/2012 15:52, Stefan Priebe - Profihost AG ha scritto:
> 
> Am 09.08.2012 15:42, schrieb Paolo Bonzini:
>> Il 09/08/2012 15:39, Stefan Priebe - Profihost AG ha scritto:
>>>> scsi-generic would indeed incur some overhead because it does not do
>>>> scatter/gather I/O directly, but scsi-hd/scsi-block do not have this
>>>> overhead.  In any case, that should be visible through the output of
>>>> perf if it is significant.
>>>
>>> Thanks for your help and replies. I'm a little bit lost on all these
>>> comments. So what to check / do next?
>>
>> Try with the deadline scheduler, and run "perf top" in guest/host if the
>> problems persist.
> 
> Thanks will do so. Right now i'm getting virtio_net virtio2: output:id 1
> is not a head!
> 
> and then network is down.

Please disable vhost, or ensure that you have the patch that Stefan
pointed you to.

Paolo