From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasiliy G Tolstov Subject: RE: failed to start centos 5 domU with maxmem=30000 Date: Thu, 12 Aug 2010 16:24:05 +0400 Message-ID: <1281615845.5454.20.camel@vase.work> References: <1281608645.5454.10.camel@vase.work> <20100812113731.GP2804@reaktio.net 1281613063.5454.15.camel@vase.work> <042d87c1-bb13-436b-a5ba-9ec1578d53d0@default> Reply-To: v.tolstov@selfip.ru Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <042d87c1-bb13-436b-a5ba-9ec1578d53d0@default> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Dan Magenheimer Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org =D0=92 =D0=A7=D1=82=D0=B2, 12/08/2010 =D0=B2 05:17 -0700, Dan Magenheimer= =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > > From: Vasiliy G Tolstov [mailto:v.tolstov@selfip.ru] > > Sent: Thursday, August 12, 2010 5:38 AM > > To: Pasi K=C3=A4rkk=C3=A4inen > > Cc: xen-devel@lists.xensource.com > > Subject: Re: [Xen-devel] failed to start centos 5 domU with > > maxmem=3D30000 > >=20 > > =D0=92 =D0=A7=D1=82=D0=B2, 12/08/2010 =D0=B2 14:37 +0300, Pasi K=C3=A4= rkk=C3=A4inen =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > > > On Thu, Aug 12, 2010 at 02:24:05PM +0400, Vasiliy G Tolstov wrote: > > > > Hello. I'm try to start centos domU pvm under sles 11 sp1 xen > > kernel > > > > with memory=3D512 and maxmem=3D30000. Centos doing boot and freez= e. > > > > If i'm try to use maxmem=3D15000 all works. > > > > > > > > Can You tell me what's wrong? > > > > > > > > > > Is the centos PV domU 32bit or 64bit ? > >=20 > > 64 bit kernel-xen. > >=20 > > I found this in xen sources: > >=20 > > /* Simple continuous piecewiese linear function: > > * max MiB -> min MiB gradient > > * 0 0 > > * 16 16 > > * 32 24 > > * 128 72 (1/2) > > * 512 168 (1/4) > > * 2048 360 (1/8) > > * 8192 552 (1/32) > > * 32768 1320 > > * 131072 4392 > > */ > >=20 > > Why this is not provided in documentation or on web site? >=20 > Hi Vasily -- >=20 > This function limits how far memory can be reduced when > ballooning a guest (including dom0). It is only a heuristic > but is intended to take into account the various overheads > a guest Linux kernel requires to manage memory to avoid > out-of-memory conditions. >=20 > But I think you are correct... the same (or similar) > function should be published as it also serves as a > guideline for the ratio between memory=3D and maxmem=3D > parameters when creating a guest: If the ratio > of maxmem divided by memory is too high, the guest > will not even boot. >=20 Is that possible to use memory=3D32 and maxmem=3D60000 ? > I am curious as to why you would specify memory=3D so > much smaller than maxmem=3D. Are you trying to overcommit > memory for guests that are often idle but sometimes use > a very large amount of memory? We want to provide ability to use small as possible memory if the guest is idle. And much as possible when the guest under heavy load. Thank You. --=20 Vasiliy G Tolstov Selfip.Ru