From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] virtio-ring: Use threshold for switching to indirect descriptors Date: Sun, 04 Dec 2011 18:33:52 +0200 Message-ID: <4EDBA0F0.4000907@redhat.com> References: <20111201075847.GA5479@redhat.com> <1322726977.3259.3.camel@lappy> <20111201102640.GB8822@redhat.com> <87zkfbre9x.fsf@rustcorp.com.au> <1322913028.3782.4.camel@lappy> <4EDB5EF0.2010909@redhat.com> <20111204120132.GB18758@redhat.com> <4EDB624A.3030403@redhat.com> <20111204151148.GA21851@redhat.com> <4EDB8EEB.4070309@redhat.com> <20111204160053.GA22501@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111204160053.GA22501@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" Cc: markmc@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Sasha Levin List-Id: virtualization@lists.linuxfoundation.org On 12/04/2011 06:00 PM, Michael S. Tsirkin wrote: > > If you > > copy descriptors, then it goes away. > > The avail ring could go away. used could if we make descriptors > writeable. IIUC it was made RO in the hope that will make it > easier for xen to adopt. Still relevant? You mean RO from the consumer side? Why can't Xen do that? > > That does suck. Are there issues in increasing the ring size? Or > > making it discontiguous? > > discontiguous ring is what indirect is, basically. No, discontiguous is more cache and prefetch friendly. With vmap(), the code doesn't even change. -- error compiling committee.c: too many arguments to function