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From: Rusty Russell <rusty@rustcorp•com.au>
To: Jason Wang <jasowang@redhat•com>, "Michael S. Tsirkin" <mst@redhat•com>
Cc: kvm@vger•kernel.org, netdev@vger•kernel.org, rick.jones2@hp•com,
	virtualization@lists•linux-foundation.org,
	levinsasha928@gmail•com, pbonzini@redhat•com,
	Tom Herbert <therbert@google•com>
Subject: Re: [PATCHv4] virtio-spec: virtio network device multiqueue support
Date: Wed, 12 Sep 2012 15:19:11 +0930	[thread overview]
Message-ID: <87har3dc4o.fsf@rustcorp.com.au> (raw)
In-Reply-To: <504DC831.1000709@redhat.com>

Jason Wang <jasowang@redhat•com> writes:
> On 09/10/2012 02:33 PM, Michael S. Tsirkin wrote:
>> A final addition: what you suggest above would be
>> "TX follows RX", right?

BTW, yes.  But it's a weird way to express what the nic is doing.

>> It is in anticipation of something like that, that I made
>> steering programming so generic.

>> I think TX follows RX is more immediately useful for reasons above
>> but we can add both to spec and let drivers and devices
>> decide what they want to support.

You mean "RX follows TX"?  ie. accelerated RFS.  I agree.

Perhaps Tom can explain how we avoid out-of-order receive for the
accelerated RFS case?  It's not clear to me, but we need to be able to
do that for virtio-net if it implements accelerated RFS.

> AFAIK, ixgbe does "rx follows tx". The only differences between ixgbe 
> and virtio-net is that ixgbe driver programs the flow director during 
> packet transmission but we suggest to do it silently in the device for 
> simplicity.

Implying the receive queue by xmit will be slightly laggy.  Don't know
if that's a problem.

Cheers,
Rusty.

  reply	other threads:[~2012-09-12  5:49 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-09 13:03 [PATCHv4] virtio-spec: virtio network device multiqueue support Michael S. Tsirkin
2012-09-10  2:12 ` Rusty Russell
2012-09-10  6:16   ` Michael S. Tsirkin
2012-09-10  6:27     ` Michael S. Tsirkin
2012-09-10  6:33       ` Michael S. Tsirkin
2012-09-10 11:00         ` Jason Wang
2012-09-12  5:49           ` Rusty Russell [this message]
2012-09-12  7:57             ` Michael S. Tsirkin
2012-09-12 14:40               ` Tom Herbert
2012-09-12 19:11                 ` Ben Hutchings
2012-09-12 14:38             ` Tom Herbert
2012-09-19  1:40               ` Rusty Russell
2012-09-19  6:12                 ` Michael S. Tsirkin
2012-09-12  0:29     ` Rusty Russell
2012-09-10 18:39   ` Rick Jones

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