[Libvir] [RFC] Check host's minimum memory.

Daniel P. Berrange berrange at redhat.com
Wed Mar 7 16:53:20 UTC 2007

On Wed, Mar 07, 2007 at 06:43:14AM -0500, Daniel Veillard wrote:
> On Tue, Mar 06, 2007 at 02:40:24PM +0900, Masayuki Sunou wrote:
> > Hi
> > 
> > The minimum value of the memory guarded with virsh setmem is 4096KB(4MB).
> > In general, when host's memory is set to 4MB, the host stops.
> > 
> > Therefore, I propose the patch to which host's minimum value of the memory
> > is guarded by 256MB.
>   I have run guests in 64MB of memory, so 256 as an arbitrary limit sounds
> way too high to me. There is some places in libvirt code where 64 is the limit
> (e.g. xend_parse_sexp_desc() if ((cur_mem > 63) && (cur_mem != max_mem)) ...)
> so if we set a limit here too that should be homogenized (using a constant
> in internal.h preferably).

This still feels wrong to me - I'm don't like the idea of libvirt enforcing
policy decisions, particularly when they're compiled in. With the current
bloated Xen python stack we probably won't go below 64 MB, but we won't always
be managing Xen, nor will Xen forever be stuck with a python stack (i hope :-). 
I'd say that if possible XenD should be fixed to honour dom0_min_memory in all
cases, rather than just when ballooning down to start a guest.

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