From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=36040 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OC8T3-0001cD-Cw for qemu-devel@nongnu.org; Wed, 12 May 2010 05:43:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OC8T1-000617-QU for qemu-devel@nongnu.org; Wed, 12 May 2010 05:43:05 -0400 Received: from mail2.shareable.org ([80.68.89.115]:47735) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OC8T1-00060y-M8 for qemu-devel@nongnu.org; Wed, 12 May 2010 05:43:03 -0400 Date: Wed, 12 May 2010 10:42:57 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH 0/2] Enable qemu block layer to not flush Message-ID: <20100512094257.GA16879@shareable.org> References: <1273528310-7051-1-git-send-email-agraf@suse.de> <4BE881CB.3070303@codemonkey.ws> <4BE884E0.5020703@codemonkey.ws> <20100511214832.GC30446@shareable.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: kwolf@redhat.com, g@shareable.org, qemu-devel@nongnu.org, Alexander Graf , hch@lst.de Stefan Hajnoczi wrote: > Why add a nop AIO operation instead of setting > BlockDriverState->enable_write_cache to zero? In that case no write > cache would be reported to the guest (just like cache=writethrough). Hmm. If the guest sees write cache absent, that prevents changing the cache policy on the host later (from not flushing to flushing), which you might want to do after an OS install has finished and booted up. -- Jamie