From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: memory size inside domU less than memory in domU config Date: Mon, 20 Jun 2011 11:07:44 -0400 Message-ID: <20110620150744.GA15740@dumpdata.com> References: <1308248350.28653.5.camel@mobile> <4DFB3FD50200007800047F63@nat28.tlf.novell.com> <1308304996.524.0.camel@vase> <20110620143611.GA15251@dumpdata.com> <1308581704.13237.9.camel@vase> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1308581704.13237.9.camel@vase> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Vasiliy G Tolstov Cc: xen-devel@lists.xensource.com, Jan Beulich List-Id: xen-devel@lists.xenproject.org On Mon, Jun 20, 2011 at 06:55:04PM +0400, Vasiliy G Tolstov wrote: > On Mon, 2011-06-20 at 10:36 -0400, Konrad Rzeszutek Wilk wrote: > > > So I tried the same experiment - a physical machine with 'mem=1G' provided > > and an PV guest with 'mem=1G'. The same exact kernel in both cases and got: > > > > Machine with 'mem=1G' on the command line. > > [ 0.000000] Memory: 1022756k/1048576k available (5851k kernel code, 452k absent, 25368k reserved, 2881k data, 688k init) > > > > PV guest: > > [ 0.000000] Memory: 1018888k/1048576k available (5851k kernel code, 448k absent, 29240k reserved, 2881k data, 688k init) > > > > So a DomU guest "eats" an extra 4MB compared to running it under baremetal. > > (Note, the DomU guest has no balloon space in this example). > > > > The memblock=debug does provide the info of what the "other" reserved regions are > > and it looks to be the matter of just going through the numbers to figure out what > > it is. > > > > Can You provide pv kernel cmdline and config file ? kernel="/home/konrad/ssd/xtt/dist/common/vmlinuz" extra="console=hvc0 debug earlyprintk=xenboot memblock=debug mem=1G" memory=1024 maxmem=1024 vcpus=1 name="latest" on_crash="preserve" vfb = [ 'vnc=1, vnclisten=0.0.0.0,vncunused=1'] disk = ['phy:/dev/vg_guest_1/data-xfs,xvda,w'] And for the baremetal: DISPLAY menu.txt SERIAL 0 115200 PROMPT 5 TIMEOUT 20 DEFAULT BAREMETAL MENU TITLE Bootable Options: LABEL Local MENU LABEL Local KERNEL chain.c32 APPEND hd0 LABEL BAREMETAL KERNEL vmlinuz APPEND mem=1G debug selinux=0 earlyprintk=serial console=ttyS0,115200 initcall_debug loglevel=10 memblock=debug