From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JmZwC-0007Rv-A7 for qemu-devel@nongnu.org; Thu, 17 Apr 2008 15:38:28 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JmZw9-0007R8-Kx for qemu-devel@nongnu.org; Thu, 17 Apr 2008 15:38:27 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JmZw9-0007R1-DT for qemu-devel@nongnu.org; Thu, 17 Apr 2008 15:38:25 -0400 Received: from mx1.redhat.com ([66.187.233.31]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1JmZw9-0004hO-1g for qemu-devel@nongnu.org; Thu, 17 Apr 2008 15:38:25 -0400 Date: Thu, 17 Apr 2008 20:38:07 +0100 From: "Daniel P. Berrange" Message-ID: <20080417193807.GB11916@redhat.com> References: <1208460412-27567-1-git-send-email-aliguori@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1208460412-27567-1-git-send-email-aliguori@us.ibm.com> Subject: [Qemu-devel] Re: [kvm-devel] [PATCH 1/3] Refactor AIO interface to allow other AIO implementations Reply-To: "Daniel P. Berrange" , qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti , qemu-devel@nongnu.org On Thu, Apr 17, 2008 at 02:26:50PM -0500, Anthony Liguori wrote: > Posix AIO, especially as used by QEMU, is not very efficient for disk IO. > This patch introduces an AIO abstract to allow multiple AIO implements to be > used. We can't simply replace posix-aio by linux-aio because linux-aio only > works on some filesystems and only with files opened with O_DIRECT. > > This patch adds a command line option (-aio) to select the AIO implementation > to be used. It avoids code motion to allow for easy review. The next patch > separates out the posix-aio implementation. This is not a very pleasant user experiance. They can not & should not be expected to figure out which AIO impl works with their particular filesystem. If the linux-aio impl doesn't work in some cases, then the code should detect these and automatically fallback to posix-aio. The user should not have to use a -aio flag to make it work. Dan. -- |: Red Hat, Engineering, Boston -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|