From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: Re: 2.6.32 pvops dom0 oom when creating a domU Date: Tue, 2 Aug 2011 12:38:48 -0400 Message-ID: <20110802163848.GO11133@dumpdata.com> References: <20110802031925.GD11133@dumpdata.com> <20110802045903.GE32373@reaktio.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <20110802045903.GE32373@reaktio.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= Cc: Daniel Musketa , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Tue, Aug 02, 2011 at 07:59:03AM +0300, Pasi K=E4rkk=E4inen wrote: > On Mon, Aug 01, 2011 at 11:19:25PM -0400, Konrad Rzeszutek Wilk wrote: > > On Tue, Aug 02, 2011 at 01:57:53AM +0200, Daniel Musketa wrote: > > > 2011/8/2 Daniel Musketa : > > > > Maybe I should say more about memory usage: > > >=20 > > > I got even more detailled logs for you in the attached file: > > >=20 > > > line 3: dom0 memory: 2,560 M > > > line 20: 21,637 M free > > > line 34: dom0_mem=3D4000M > > > line 47: domU memory =3D '2800' > > > line 72: OOM begins > > > line 157: key 'm' on (XEN) console > >=20 > > Try the 'mem=3D4G' in your Linux line (along with the one in your hyp= ervisor). > > The problem is that Dom0 sets up pagetables for the 32GB even thought= it is never > > going to use it - the 'mem=3D4G' should fix that for you. > >=20 >=20 > Hmm.. Does that explain the dom0 OOM ? Why does dom0 OOM when creating = a domU ? > In this case dom0 didn't have to be ballooned down, it shouldn't see an= y changes to its memory?=20 So Linux kernel looks at the E820 and sees 30GB of "reserved" memory (tha= t memory is what dom0 "thinks" it might balloon too - even thought it won't ever do).= So Linux thinks to itself: "OK, we _might_ use that in the future, so lets create the pag= etables for it". And we end up with 800MBs (or more) of pagetables that never end up using= . That 800MB does not get released or what not. So your dom0 ends up with 300MB or so (say with= dom0_mem=3Dmax:1G) and we end up with the OOM happily killing things. The idea, now that Daniel Kipper's patches are in - to use the memory hot= plug API to balloon pages in and out. That should make this much easier. >=20 > Just trying to understand it better :)=20 Of course. Thanks for asking! >=20 > -- Pasi >=20 >=20 > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel