From: Ewan M. M. <ec...@yo...> - 2002-07-11 18:13:23
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On Thu, 11 Jul 2002, Patrick Thomas wrote: > > Along the same lines, is there a way to run multiple UMLs in a system > _without_ guaranteeing them a slot of memory ? <snip> > If you just played fast and loose, I'll bet you could oversell, so to > speak, the memory by at least double. > Is there a way to do this ? Surely if you have tmpfs on /tmp[1] and the UMLs aren't using all of the memory you've allocated them the host will just swap out the unused bits if it needs the ram for something else, you'd need enough swap on the host to hold the total allocated UML memory, butyou wouldn't need enough ram. Ewan [1] Someone was telling me about Posix shared memory the other day, essentially you mount (something like) tmpfs on /dev/shm, create a file, unlink it, and past te file handle around everyone that you want to be able to share the memory. If I understand it correctly this is exactly what UML does to share memory between all of the processes on the UML system but it uses a file in /tmp rather than /dev/shm. Since the performance of UML sucks if /tmp is actually on a disk, and some/many distros have a default setup with /tmp on disk, but tmpfs on /dev/shm would it be a good idea to move UMLs memory file from /tmp to /dev/shm? |