On Wed, May 02, 2007 at 02:30:53PM +0200, Jan Michael wrote: I've been thinking about this & I'm not sure that dom0-min-mem is really something we want to expose, particularly for the scenario you describe. dom0-min-mem is a completely artificial threshold set by Xen that does not really provide a very reliable solution to determining whether there is enough memory to start new domains. dom0-min0-mem may be set to 128 MB, but if your Dom0 is using 500 MB currently, then you can't really say that you can safely balloon it down to 128MB - it'll end up with swap-death. In the QEMU / KVM case, there is no concept of dom0-min-mem at all, and you not only have to take in account physical memory, and memory of the host, but also memory which may be being used by other apps in the host. If an app needs to decide whether there is enough memory on a host to safely create a new guest, then it really needs to be considering the actual usage within the host OS - eg, the finer breakdown of figures from /proc/meminfo for example at the very least. For more advanced uses one would also want agents inside every guest reporting whether they're actually using their complete allocation of RAM too. And so on, expanding to look at all sorts of aspects of the system. So in this context Dom0-min-mem is not really a generally applicable concept in virtualization, and it is also not particularly useful data either IMHO. Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|