On Fri, 2004-06-18 at 09:11, Tom Lane wrote:
> "Domenico Sgarbossa" <domenico@xtecnica.com> writes:
> > so when the users go home, i've got something like 15/20000kb free ram, the
> > rest is cached and 0kb of swap...
> > It seems that when pg_dump starts the cached memory isn't released so the
> > system begin to swap,
>
> A sane kernel should drop disk buffers rather than swapping. We heard
> recently about a bug in some versions of the Linux kernel that cause it
> to prefer swapping to discarding disk cache, though. It sounds like
> that's what you're hitting. Look into newer kernels ...
This was a common problem in the linux 2.4 series kernels, but has
supposedly been fixed in the 2.6 kernels. Having lots of memory and
turning off swap will "fix" the problem in 2.4, but if you run out of
real mem, you're hosed.