netdev - Re: [PATCH] macvtap: Fix macvtap_get

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Message-ID: <4ED310CF.6010306@redhat.com>
Date:	Mon, 28 Nov 2011 12:40:47 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	David Miller <davem@...emloft.net>, krkumar2@...ibm.com,
	arnd@...db.de, levinsasha928@...il.com, netdev@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] macvtap: Fix macvtap_get_queue to use rxhash first

On 11/28/2011 01:23 AM, Michael S. Tsirkin wrote:
> On Fri, Nov 25, 2011 at 01:35:52AM -0500, David Miller wrote:
>> From: Krishna Kumar2<krkumar2@...ibm.com>
>> Date: Fri, 25 Nov 2011 09:39:11 +0530
>>
>>> Jason Wang<jasowang@...hat.com>  wrote on 11/25/2011 08:51:57 AM:
>>>> My description is not clear again :(
>>>> I mean the same vhost thead:
>>>>
>>>> vhost thread #0 transmits packets of flow A on processor M
>>>> ...
>>>> vhost thread #0 move to another process N and start to transmit packets
>>>> of flow A
>>> Thanks for clarifying. Yes, binding vhosts to CPU's
>>> makes the incoming packet go to the same vhost each
>>> time. BTW, are you doing any binding and/or irqbalance
>>> when you run your tests? I am not running either at
>>> this time, but thought both might be useful.
>> So are we going with this patch or are we saying that vhost binding
>> is a requirement?
> I think it's a good idea to make sure we understand the problem
> root cause well before applying the patch. We still
> have a bit of time before 3.2. In particular, why does
> the vhost thread bounce between CPUs so much?

Other than this, since we could not assume the behavior of the under 
nic, using rxhash to identify a flow is more generic way.
>
> Long term it seems the best way is to expose the preferred mapping
> from the guest and forward it to the device.
>

I was working on this and hope to post it soon.
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