From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LiqnU-0002pY-Aj for qemu-devel@nongnu.org; Sun, 15 Mar 2009 09:54:36 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LiqnP-0002nl-Id for qemu-devel@nongnu.org; Sun, 15 Mar 2009 09:54:35 -0400 Received: from [199.232.76.173] (port=36173 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LiqnP-0002ne-Cg for qemu-devel@nongnu.org; Sun, 15 Mar 2009 09:54:31 -0400 Received: from mx20.gnu.org ([199.232.41.8]:58027) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LiqnO-0005bb-Si for qemu-devel@nongnu.org; Sun, 15 Mar 2009 09:54:30 -0400 Received: from mx2.redhat.com ([66.187.237.31]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LiqnN-0007tY-UK for qemu-devel@nongnu.org; Sun, 15 Mar 2009 09:54:30 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n2FDsSSH026282 for ; Sun, 15 Mar 2009 09:54:28 -0400 Message-ID: <49BD0892.3060604@redhat.com> Date: Sun, 15 Mar 2009 15:54:26 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API References: <1236862631-22918-1-git-send-email-avi@redhat.com> <1236862631-22918-2-git-send-email-avi@redhat.com> <20090314143327.GA26791@lst.de> In-Reply-To: <20090314143327.GA26791@lst.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Christoph Hellwig wrote: > Hower the way the new > API is designed somewhat gets in the way of my patch series to support > Gerd's native preadv/pwritev. > > Can you point out specific issues? > One thing I wonder is why we go through the block layer at all for SG. > It is actually backed by a char device that doesn't have semantics like > a block device at all, given that it can't be seekend and is accessed > at byte granularity. We could just go directly to the native Linus > syscalls from scsi-generic.c (or a scsi-generic-linux.c if we want > some level of abstraction). I'll cook up a patch trying that once I'm > back home Using the block layer has the advantage of common setup, statistics, and management. I agree that the actual data movement is horribly out of sync with the other format drivers. Come to think of it, I don't see how statistics can work, so maybe it is a good idea to separate the two paths completely. -- error compiling committee.c: too many arguments to function