From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] virtio-blk: add SGI_IO passthru support Date: Mon, 27 Apr 2009 12:15:31 +0300 Message-ID: <49F577B3.5050706@redhat.com> References: <20090427082606.GA32604@lst.de> <20090427082914.GA383@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Christian Borntraeger , Rusty Russell , qemu-devel@nongnu.org, kvm@vger.kernel.org, Hannes Reinecke To: Christoph Hellwig Return-path: In-Reply-To: <20090427082914.GA383@lst.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org Christoph Hellwig wrote: > [had the qemu list address wrong the first time, reply to this message, > not the previous if you were on Cc] > > > Add support for SG_IO passthru (packet commands) to the virtio-blk > backend. Conceptually based on an older patch from Hannes Reinecke > but largely rewritten to match the code structure and layering in > virtio-blk. > > Note that currently we issue the hose SG_IO synchronously. We could > easily switch to async I/O, but that would required either bloating > the VirtIOBlockReq by the size of struct sg_io_hdr or an additional > memory allocation for each SG_IO request. > I think that's worthwhile. The extra bloat is trivial (especially as the number of inflight virtio requests is tightly bounded), and stalling the vcpu for requests is a pain. -- error compiling committee.c: too many arguments to function