On Tue, Jul 10, 2001 at 09:39:01PM -0700, Cameron Kaiser wrote:
> There's such a thing as too much swap, sure, but I've run into far more
> cases where I guessed way too low than too high. My ANS box has run out of
> paging space at least twice, and that wasn't pretty (granted AIX is much
> more aggressive about VM allocation even with free memory available, but I
> digress). I'd rather guess high and be debugging performance than guess low
> and crash. But that's my preference :-)

I guess.

When I first got my newest machine (an intel-esque system, it's an
800 Mhz AMD chip), I only bought a 128 MB DIMM. I knew I was going
to want more memory later, so I configured a 512 MB swap partition.
Interactive performance in X when any serious disk activity was
going on was a bitch because of UBC's reclaiming the pages of any X
window that wasn't in my active viewing frame (I use a virtual
window manager, obviously), and they had to be swapped in when I
jumped around (which I do pretty frequently). I recently added a
256 MB DIMM to that system and didn't change the swap configuration.
Performance is much improved, and I've certainly not had any
stability problems yet.

I think UBC is going to lead to the old swap = 2 x physical memory
formula being a really good idea again.

-- 
       ~ g r @ eclipsed.net