From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bronek Kozicki <brok@spamcop.net>
Subject: Re: vhost-[pid] 100% CPU
Date: Sun, 06 Apr 2014 18:35:04 +0100
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To: Simon Chen <simonchennj@gmail.com>, kvm@vger.kernel.org
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On 06/04/2014 15:06, Simon Chen wrote:
> Hello,
>
> I am using QEMU 1.6.0 on Linux 3.10.21. My VMs are using vhost-net in
> a typical OpenStack setup: VM1->tap->linux
> bridge->OVS->host1->physical network->host2->OVS->linux
> bridge->tap->VM2.
>
> It seems that under heavy network load, the vhost-[pid] processes on
> the receiving side is using 100% CPU. The sender side has over 85%
> utilized.
>
> I am seeing unsatisfactory VM to VM network performance (using iperf
> 16 concurrent TCP connections, I can only get 1.5Gbps, while I've
> heard people got to over 6Gbps at least), and I wonder if it has
> something to do with vhost-net maxing out on CPU. If so, is there
> anything I can tune the system?

You could dedicate network card to your virtual machine, using PCI 
passthrough.


B.