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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Krishna Kumar <krkumar2@in.ibm.com>
Cc: davem@davemloft.net, eric.dumazet@gmail.com, kvm@vger.kernel.org,
	netdev@vger.kernel.org, rusty@rustcorp.com.au
Subject: Re: [PATCH 2/4] [RFC] virtio: Introduce new API to get free space
Date: Wed, 4 May 2011 23:00:23 +0300	[thread overview]
Message-ID: <20110504200023.GA20303@redhat.com> (raw)
In-Reply-To: <20110504145019.GB15823@redhat.com>

On Wed, May 04, 2011 at 05:50:19PM +0300, Michael S. Tsirkin wrote:
> > @@ -185,11 +193,6 @@ int virtqueue_add_buf_gfp(struct virtque
> >  	if (vq->num_free < out + in) {
> >  		pr_debug("Can't add buf len %i - avail = %i\n",
> >  			 out + in, vq->num_free);
> > -		/* FIXME: for historical reasons, we force a notify here if
> > -		 * there are outgoing parts to the buffer.  Presumably the
> > -		 * host should service the ring ASAP. */
> > -		if (out)
> > -			vq->notify(&vq->vq);
> >  		END_USE(vq);
> >  		return -ENOSPC;
> >  	}
> 
> This will break qemu versions 0.13 and back.
> I'm adding some new virtio ring flags, we'll be
> able to reuse one of these to mean 'no need for
> work around', I think.

Not really, it wont. We shall almost never get here at all.
But then, why would this help performance?

> -- 
> MST

  reply	other threads:[~2011-05-04 20:00 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-04 14:02 [PATCH 0/4] [RFC] virtio-net: Improve small packet performance Krishna Kumar
2011-05-04 14:03 ` [PATCH 1/4] [RFC] netdevice: Introduce per-txq xmit_restart Krishna Kumar
2011-05-04 14:03 ` [PATCH 2/4] [RFC] virtio: Introduce new API to get free space Krishna Kumar
2011-05-04 14:50   ` Michael S. Tsirkin
2011-05-04 20:00     ` Michael S. Tsirkin [this message]
2011-05-05  3:08       ` Krishna Kumar2
2011-05-05  9:13       ` Michael S. Tsirkin
2011-05-04 19:58   ` Michael S. Tsirkin
2011-05-04 14:03 ` [PATCH 3/4] [RFC] virtio-net: Changes to virtio-net driver Krishna Kumar
2011-05-05 12:28   ` Michael S. Tsirkin
2011-05-04 14:03 ` [PATCH 4/4] [RFC] sched: Changes to dequeue_skb Krishna Kumar
2011-05-04 14:46 ` [PATCH 0/4] [RFC] virtio-net: Improve small packet performance Michael S. Tsirkin
2011-05-04 14:59   ` Krishna Kumar2
2011-05-04 21:23     ` Michael S. Tsirkin
2011-05-05  8:03       ` Krishna Kumar2
2011-05-05  9:04         ` Michael S. Tsirkin
2011-05-05  9:43           ` Krishna Kumar2
2011-05-05 10:12             ` Michael S. Tsirkin
2011-05-05 10:57               ` Krishna Kumar2
2011-05-05 15:27           ` Krishna Kumar2
2011-05-05 15:34             ` Michael S. Tsirkin
2011-05-07  7:15               ` Krishna Kumar2
2011-05-05 15:36             ` Krishna Kumar2
2011-05-05 15:37               ` Michael S. Tsirkin
2011-05-05 15:42             ` Michael S. Tsirkin

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