From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:40110) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QodEx-0002NT-Py for qemu-devel@nongnu.org; Wed, 03 Aug 2011 11:20:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QodEc-0006vQ-W5 for qemu-devel@nongnu.org; Wed, 03 Aug 2011 11:19:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24890) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QodEc-0006sc-Lf for qemu-devel@nongnu.org; Wed, 03 Aug 2011 11:19:50 -0400 Message-ID: <4E3967B4.8080608@redhat.com> Date: Wed, 03 Aug 2011 17:22:28 +0200 From: Kevin Wolf MIME-Version: 1.0 References: <1312191547-12777-1-git-send-email-stefanha@linux.vnet.ibm.com> In-Reply-To: <1312191547-12777-1-git-send-email-stefanha@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] block: add cache=directsync parameter to -drive List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Andrew Theurer , qemu-devel@nongnu.org, Christoph Hellwig Am 01.08.2011 11:39, schrieb Stefan Hajnoczi: > This patch adds -drive cache=directsync for O_DIRECT | O_SYNC host file > I/O with no disk write cache presented to the guest. > > This mode is useful when guests may not be sending flushes when > appropriate and therefore leave data at risk in case of power failure. > When cache=directsync is used, write operations are only completed to > the guest when data is safely on disk. > > This new mode is like cache=writethrough but it bypasses the host page > cache. > > Signed-off-by: Stefan Hajnoczi qemu-img has another parser for cache options that must be changed. This should probably be refactored to a single implementation in block.c. Kevin