From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36389) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VH9vv-0004EK-Ky for qemu-devel@nongnu.org; Wed, 04 Sep 2013 06:03:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VH9vp-0000yn-35 for qemu-devel@nongnu.org; Wed, 04 Sep 2013 06:03:31 -0400 Date: Wed, 4 Sep 2013 12:03:21 +0200 From: Stefan Hajnoczi Message-ID: <20130904100321.GE9654@stefanha-thinkpad.redhat.com> References: <2013090411470490667813@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2013090411470490667813@163.com> Subject: Re: [Qemu-devel] question about qemu disk cache mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xuanmao_001 Cc: Kevin Wolf , qemu-devel , qemu-discuss On Wed, Sep 04, 2013 at 11:47:04AM +0800, xuanmao_001 wrote: > my qemu-kvm version is 1.0.1 > I would like to figure out the qemu disk cache mode. I have visited the qemu-options.hx > there is two cache that I didn't understand: the host cache page and the qemu disk write cache. > > Is "host page cache" only used for read. and "qemu disk write cache" used for writing. > > which cache the data reached first? host page cache or qemu disk write cache? The following slides might be helpful in explaining the caching modes: https://events.linuxfoundation.org/slides/2011/linuxcon-japan/lcj2011_hajnoczi.pdf Stefan