Re: why swap at all?

[William Lee Irwin III <wli@holomorphy.com>]

On Wed, May 26, 2004 at 10:00:06PM +0900, Satoshi Oshima wrote:
> I really agree. And I think swappoff is not enough. Some of my
> customers have over 4GB of memory. RDMS, Java Virtual Machine or Grid
> system (like Globus tool kit) run on the servers. Those kinds of
> application make a lot of threads and they have huge amount of shared
> memory. And those shared memory is sometimes mlocked. I think, in
> those systems, memory aging itself is useless or obstructive in worst
> case. Because mlocked pages which can't be swapped off are on the LRU
> list. In such case, aging-off (relevant to process) is effective, I
> think. Of course, I agree that swap-off or aging-off is NEVER always
> useful. On the contrary, these functions may be required by very
> small number of user. But it is very important that we can choose 
> how we use the OS.

Could you try CONFIG_SWAP=n to see if that makes a difference?
More aggressive non-paging methods could be devised if not, e.g.
CONFIG_MMU=n support of various kinds for hardware supporting paging
and virtual memory (this is a suggestion, not an offer to implement).


-- wli