From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Magenheimer Subject: Re: can not use all available memory Date: Mon, 26 Nov 2012 13:47:39 -0800 (PST) Message-ID: References: <1353674827.16973.4.camel@zakaz.uk.xensource.com> <20121123125503.GX8912@reaktio.net> <1353676553.16973.12.camel@zakaz.uk.xensource.com> <20121123132920.GY8912@reaktio.net> <1353677623.16973.13.camel@zakaz.uk.xensource.com> <1545900898.20121126192533@eikelenboom.it> <672d364a-6d34-4c89-b0fb-5af989877117@default> <20121126202411.GA8912@reaktio.net> <20121126213249.GA37842@ocelot.phlegethon.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121126213249.GA37842@ocelot.phlegethon.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Tim Deegan Cc: Sander Eikelenboom , xen-devel@lists.xensource.com, Alexander Bienzeisler , Ian Campbell List-Id: xen-devel@lists.xenproject.org > From: Tim Deegan [mailto:tim@xen.org] > Subject: Re: [Xen-devel] can not use all available memory > > At 12:37 -0800 on 26 Nov (1353933449), Dan Magenheimer wrote: > > > > I could be wrong (and I am confident someone will correct me if I am) but > > > > I think this is because the Citrix memory model assumes there is an > > > > inference-driven policy engine for load-balancing memory across competing > > > > virtual machines ("squeezed"). I suspect squeezed returns unallocated > > > > xen "free" memory to dom0. > > > > I forgot... it is called Dynamic Memory Control (DMC), not squeezed > > in the XenServer product. > > AFAIK XenServer uses dom0_mem= and doesn't balloon com0 after boot time. > The idea of ballooning all free memory into dom0 is a xl-ism, inherited > from xend, and not really a "Citrix" one. It's useful if you've > installed xen on a machine where dom0 is otherwise your main OS, but not > particularly for a dedicated platform. "inherited from xend"... was the autoballoon default the same in xend? I don't recall ever turning it off manually and, when testing tmem, I'm sure I would have had to. Or maybe xend did use hypervisor free memory before trying to autoballoon dom0?