From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] Make virtio devices multi-function Date: Tue, 22 Apr 2008 11:31:11 -0500 Message-ID: <480E12CF.9080108@codemonkey.ws> References: <1208873728-10194-1-git-send-email-aliguori@us.ibm.com> <480DF70D.8010609@qumranet.com> <480DFA3B.2000401@codemonkey.ws> <480DFB87.6090608@qumranet.com> <20080422153602.GA15542@dmt> <480E0FC0.4000401@codemonkey.ws> <480E11E2.3040706@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Chris Wright , Marcelo Tosatti To: Avi Kivity Return-path: In-Reply-To: <480E11E2.3040706@qumranet.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Anthony Liguori wrote: >> >> I think we need to decide what we want to target in terms of upper >> limits. >> >> With a bridge or two, we can probably easily do 128. >> >> If we really want to push things, I think we should do a PCI based >> virtio controller. I doubt a large number of PCI devices is ever >> going to perform very well b/c of interrupt sharing and some of the >> assumptions in virtio_pci. >> >> If we implement a controller, we can use a single interrupt, but >> multiplex multiple notifications on that single interrupt. We can >> also be more aggressive about using shared memory instead of PCI >> config space which would reduce the overall number of exits. >> >> We could easily support a very large number of devices this way. But >> again, what do we want to target for now? > > I think that for networking we should keep things as is. I don't see > anybody using 100 virtual NICs. > > For mass storage, we should follow the SCSI model with a single device > serving multiple disks, similar to what you suggest. Not sure if the > device should have a single queue or one queue per disk. My latest thought it to do a virtio-based virtio controller. We could avoid creating one in QEMU unless we detect an abnormally large number of disks or something. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone