>But today, having 100 linux servers share the same read/only >disk, and all 100 cache the same disk is undesirable when >MDC could do it so well for all of them.
This is going to improve in the near future. As for each Linux buffering its private data, I think that is the question of global vs local optimisation. As long as VM has plenty of storage I don't mind Linux cache its data. But when VM runs out of storage and the Linux guest starts to get page faults there is a lot of damage. What I was thinking about is a device driver that talks to CP and sees when the guest starts to get page faults. It can then allocate memory in Linux (and not use it) to reduce the footprint of the guest. I think that would force Linux to give up I/O buffers sooner. When the processes in Linux need more memory it would cause some swapping but it would swap out those pages that I allocated (but don't reference) and thus do little harm. Instead of talking to CP it might be possible to watch the pseudo page faults (but that might require a change in Linux to also use it in kernel mode). Rob
