"Domenico Sgarbossa" <domenico(at)xtecnica(dot)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 ...
regards, tom lane