From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 2/4] [RFC] virtio: Introduce new API to get free space Date: Wed, 4 May 2011 23:00:23 +0300 Message-ID: <20110504200023.GA20303@redhat.com> References: <20110504140258.14817.66596.sendpatchset@krkumar2.in.ibm.com> <20110504140319.14817.23145.sendpatchset@krkumar2.in.ibm.com> <20110504145019.GB15823@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, eric.dumazet@gmail.com, kvm@vger.kernel.org, netdev@vger.kernel.org, rusty@rustcorp.com.au To: Krishna Kumar Return-path: Received: from mx1.redhat.com ([209.132.183.28]:16388 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755606Ab1EDUAt (ORCPT ); Wed, 4 May 2011 16:00:49 -0400 Content-Disposition: inline In-Reply-To: <20110504145019.GB15823@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: 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