linux-kernel - Re: [RFC PATCH v9 00/16] Provide a zero-copy method on KVM virtio-net.

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Date:	Mon, 13 Sep 2010 14:35:53 -0700
From:	Shirley Ma <mashirle@...ibm.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	xiaohui.xin@...el.com, netdev@...r.kernel.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, mingo@...e.hu, davem@...emloft.net,
	herbert@...dor.hengli.com.au, jdike@...ux.intel.com
Subject: Re: [RFC PATCH v9 00/16] Provide a zero-copy method on KVM
 virtio-net.

On Fri, 2010-09-03 at 13:52 +0300, Michael S. Tsirkin wrote:
> > When binding vhost thread to cpu3, qemu I/O thread to cpu2, macvtap
> zero
> > copy patch can get 9.4Gb/s. 
> > 
> > TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to
> 192.168.10.74 (192.168.10.74) port 0 AF_INET : cpu bind
> > Recv   Send    Send                          Utilization
> Service Demand
> > Socket Socket  Message  Elapsed              Send     Recv     Send
> Recv
> > Size   Size    Size     Time     Throughput  local    remote   local
> remote
> > bytes  bytes   bytes    secs.    10^6bits/s  % S      % S      us/KB
> us/KB
> > 
> >  87380  16384  65536    60.00      9408.19   55.69    8.45     0.970
> 0.589
> > 
> > Shirley
> 
> OTOH CPU utilization is up too.

w/i macvtap zero copy patch, the BW can reach link w/i more cpu usage,
w/o macvtap zero copy patch, the BW can't be up to link speed. To
achieve same BW, CPU utilization is lower when using zero copy.

Shirley

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