netdev - RE: Change dev->needed_headroom of virtio_net to make Patch"virtio-net: put virtio net header inline with data"work better

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Date:	Thu, 24 Apr 2014 11:50:24 +0000
From:	"Zhangjie (HZ)" <zhangjie14@...wei.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	"jasowang@...hat.com" <jasowang@...hat.com>,
	Qinchuanyu <qinchuanyu@...wei.com>,
	Liuyongan <liuyongan@...wei.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: Change dev->needed_headroom of virtio_net to make
 Patch"virtio-net: put virtio net header inline with data"work better

Thank you very much!
I will post a patch tomorrow.

--Best wishes!
//Zhang Jie
-----Original Message-----
From: Michael S. Tsirkin [mailto:mst@...hat.com] 
Sent: Thursday, April 24, 2014 7:45 PM
To: Zhangjie (HZ)
Cc: jasowang@...hat.com; Qinchuanyu; Liuyongan; kvm@...r.kernel.org; netdev@...r.kernel.org
Subject: Re: Change dev->needed_headroom of virtio_net to make Patch"virtio-net: put virtio net header inline with data"work better

On Thu, Apr 24, 2014 at 10:19:58AM +0000, Zhangjie (HZ) wrote:
> Hi!
> 
> Patch “virtio-net: put virtio net header inline with data” , has a 
> notable improvement for TCP packages.
> 
> But UDP packages from virtio_net nic, do not have enough head room. I 
> wonder if we can set dev->needed_headroom
> 
> to the size of virtio net header, so as to put the header in. By doing 
> this, udp get about 5% improvement in bandwidth.

Sounds like a reasonable thing to do.
Want to post the patch so people can try it out?

>  
> 
> --
> 
> Thanks,
> 
> //Zhang Jie
> 
>  
>