[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] failed to start centos 5 domU with maxmem=30000
> From: Vasiliy G Tolstov [mailto:v.tolstov@xxxxxxxxx] > Sent: Thursday, August 12, 2010 5:38 AM > To: Pasi KÃrkkÃinen > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx > Subject: Re: [Xen-devel] failed to start centos 5 domU with > maxmem=30000 > > Ð ÐÑÐ, 12/08/2010 Ð 14:37 +0300, Pasi KÃrkkÃinen ÐÐÑÐÑ: > > 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=512 and maxmem=30000. Centos doing boot and freeze. > > > If i'm try to use maxmem=15000 all works. > > > > > > Can You tell me what's wrong? > > > > > > > Is the centos PV domU 32bit or 64bit ? > > 64 bit kernel-xen. > > I found this in xen sources: > > /* 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 > */ > > Why this is not provided in documentation or on web site? Hi Vasily -- 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. 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= and maxmem= parameters when creating a guest: If the ratio of maxmem divided by memory is too high, the guest will not even boot. I am curious as to why you would specify memory= so much smaller than maxmem=. Are you trying to overcommit memory for guests that are often idle but sometimes use a very large amount of memory? Thanks, Dan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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