Re: Memory Allocation

"Ryan Hansen" <ryan(dot)hansen(at)brightbuilders(dot)com> writes:
> I have a fairly robust server running Ubuntu Hardy Heron, 24 GB of memory,
> and I've tried to commit half the memory to PG's shared buffer, but it seems
> to fail. I'm setting the kernel shared memory accordingly using sysctl,
> which seems to work fine, but when I set the shared buffer in PG and restart
> the service, it fails if it's above about 8 GB.

Fails how? And what PG version is that?

FWIW, while there are various schools of thought on how large to make
shared_buffers, pretty much everybody agrees that half of physical RAM
is not the sweet spot. What you're likely to get is maximal
inefficiency with every active disk page cached twice --- once in kernel
space and once in shared_buffers.

regards, tom lane