On 15 Sep 2002 at 11:47, Tom Lane wrote:
> Ericson Smith <eric@did-it.com> writes:
> > Using the bigmem kernel and RH7.3, we were able to set Postgresql shared
> > memory to 3.2Gigs (out of 6GB Ram). Does this mean that Postgresql will
> > only use the first 2Gigs?
> In any case, pushing PG's shared memory to 50% of physical RAM is
> completely counterproductive. See past discussions (mostly on
> -hackers and -admin if memory serves) about appropriate sizing of
> shared buffers. There are different schools of thought about this,
> but I think everyone agrees that a shared-buffer pool that's roughly
> equal to the size of the kernel's disk buffer cache is a waste of
> memory. One should be much bigger than the other. I personally think
> it's appropriate to let the kernel cache do most of the work, and so
> I favor a shared_buffers setting of just a few thousand.
So you mean, at large sites tuning kernel disks buffer becomes a part of tuning
postgres?
IIRC kernel disk caching behaviour varies across unices and I really don't know
if kernel will honour the caching request with cache size more than say 2Gigs..
Linux kernel is a different story. It eats everything it can but still..
That comes back to my other question.. Is it possible to change page size and
would that be beneficial under some conditions?
I am not asking because I don't want to listen to you but I would better back
my claims when I am making an evaluation proposals. Do you have any numbers
handy? (I will search them as well..)
Bye
Shridhar
--
Painting, n.: The art of protecting flat surfaces from the weather, and
exposing them to the critic. -- Ambrose Bierce
