From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Lee Powell Subject: Re: Re: [kvm] Re: Questions about duplicate memory work Date: Tue, 27 Sep 2011 00:38:42 -0700 Message-ID: <20110927073842.GY18099@stodi.digitalkingdom.org> References: <20110925044511.GI30419@stodi.digitalkingdom.org> <20110926071803.GE18099@stodi.digitalkingdom.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Emmanuel Noobadmin Return-path: Received: from 173-13-139-236-sfba.hfc.comcastbusiness.net ([173.13.139.236]:40053 "EHLO stodi.digitalkingdom.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751785Ab1I0Hin (ORCPT ); Tue, 27 Sep 2011 03:38:43 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Sep 26, 2011 at 04:15:37PM +0800, Emmanuel Noobadmin wrote: > On 9/26/11, Robin Lee Powell wrote: > > On Mon, Sep 26, 2011 at 01:49:18PM +0800, Emmanuel Noobadmin wrote: > >> On 9/25/11, Robin Lee Powell wrote: > >> > > >> > OK, so I've got a Linux host, and a bunch of Linux VMs. > >> > > >> > This means that the host *and* all tho VMs do their own disk > >> > caches/buffers and do their own swap as well. > >> > >> If I'm not wrong, that's why the recommended and current default > >> in libvirtd is to create storage devices with no caching to remove > >> one layer of duplication. > > > > How do you do that? I have my VMs using LVs created on the host as > > their disks, but I'm open to other methods if there are significant > > advantages. > > It's unrelated to what you're actually using as the disks, whether > file or block devices like LVs. I think it just makes KVM tell the > host not to cache I/O done on the storage device. Wait, hold on, I think I had it backwards. It tells the *host* to not cache the device in question, or the *VMs* to not cache the device in question? -Robin