From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH] virtio-ring: Use threshold for switching to indirect descriptors Date: Sun, 04 Dec 2011 19:39:34 +0200 Message-ID: <1323020374.3256.5.camel@lappy> References: <4ED4F30F.8000603@redhat.com> <1322669511.3985.8.camel@lappy> <87wrahrp0u.fsf@rustcorp.com.au> <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> <1323000831.4205.4.camel@lappy> <20111204162221.GB22501@redhat.com> <1323020088.3256.3.camel@lappy> <4EDBAFC5.2010405@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4EDBAFC5.2010405@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: Avi Kivity Cc: markmc@redhat.com, kvm@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Sun, 2011-12-04 at 19:37 +0200, Avi Kivity wrote: > On 12/04/2011 07:34 PM, Sasha Levin wrote: > > > > > > I'm confused. didn't you see a bigger benefit for guest->host by > > > switching indirect off? > > > > The 5% improvement is over the 'regular' indirect on, not over indirect > > off. Sorry for the confusion there. > > > > I suggested this change regardless of the outcome of indirect descriptor > > threshold discussion, since it would help anyways. > > For net, this makes sense. For block, it reduces the effective queue > depth, so it's not a trivial change. It probably makes sense there too, > though. It doesn't have to be limited at that number, anything above that can go through the regular kmalloc() path. -- Sasha.