new memory = more swap?

[Marc Schwartz]

On Thu, 2004-03-25 at 13:34, duncan brown wrote:
> marc,
> the more swap you have the more likely you'll be to have things go
> into swap.  i only have 256mb of ram and i'm only using 70mb of swap,
> and it doesn't look like the number's changing much if at all.  you
> don't want to get too crazy with swap.

I agree that you do not want to go too crazy with swap space.

However, my understanding with it has always been that it will be used
only once you start getting low on physical RAM and generally not
before. Presumably, there are some exceptions in the swap logic.

The kernel/MM will generally push pages to swap, principally based upon
process priority and status (ie. running vs. sleeping), "swap data
before code" and other such things.

I am certainly no kernel maven, but if in general that is true, then
there should be no correlation to the amount of swap space allocated and
the "tendency" to use it. That sounds like an example of "Post Hoc, Ergo
Propter Hoc"

;-)

I would say that if there is any correlative statement to be made it
would be "the more physical RAM you have, the less likely you are to
need swap space of any size". My observations from a sample size of one,
would suggest that (for me at least), at 2GB RAM, I could probably get
away with no swap space at all...

Cheers,

Marc