From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MGVVX-0001gp-ME for qemu-devel@nongnu.org; Tue, 16 Jun 2009 06:03:11 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MGVVS-0001dN-Ke for qemu-devel@nongnu.org; Tue, 16 Jun 2009 06:03:10 -0400 Received: from [199.232.76.173] (port=60224 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MGVVS-0001d5-CE for qemu-devel@nongnu.org; Tue, 16 Jun 2009 06:03:06 -0400 Received: from mx2.redhat.com ([66.187.237.31]:43471) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MGVVR-0007EZ-LB for qemu-devel@nongnu.org; Tue, 16 Jun 2009 06:03:05 -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 n5GA31f0013884 for ; Tue, 16 Jun 2009 06:03:01 -0400 Message-ID: <4A376DEB.4070008@redhat.com> Date: Tue, 16 Jun 2009 13:03:23 +0300 From: Dor Laor MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 0/3] qcow2: Write complete sectors References: <1245144690-27805-1-git-send-email-kwolf@redhat.com> In-Reply-To: <1245144690-27805-1-git-send-email-kwolf@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: dlaor@redhat.com List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org On 06/16/2009 12:31 PM, Kevin Wolf wrote: > Once upon a time, there was a bdrv_pwrite that actually wrote single bytes to > the file... However, today it is emulated by a read-modify-write cycle which > aligns the request to sector size. This is slow. And we don't need it: qcow2 > often has the complete sector in memory, we don't need to read it from the disk > again. > > These patches change the writes to L1 tables, L2 tables and refcount blocks to > write complete sectors instead of single entries. > > This series depends on the qcow2 split to apply cleanly. > > If it's not an RFC, you better prepare a git tree for Anthony to pull from and described how did you test it. Maybe committing the qemu-io scripts would also be a move in the right direction. Cheers, Dor > Kevin Wolf (3): > l2_allocate: Write complete sectors > alloc_cluster_link_l2: Write complete sectors > update_refcount: Write complete sectors > > block/qcow2-cluster.c | 61 +++++++++++++++++++++++++++++++++++++++++------ > block/qcow2-refcount.c | 34 ++++++++++++++++++++------ > 2 files changed, 79 insertions(+), 16 deletions(-) > > > >