Re: FreeBSD and large shared_buffers a no-go?

On Jan 7, 2009, at 12:30 PM, Tom Lane wrote:

> Kirk Strauser <kirk(at)strauser(dot)com> writes:
>> First, shmget is asking for a lot less than shmmax - why is it
>> failing?
>
> Check to see if things work as expected when you have shmmax and
> shmall
> set to a shade less than 2GB and fail when they are a shade more. If
> so, it would seem there's a signed-integer-overflow bug somewhere in
> the
> kernel's handling of shmem requests ... which would be a reportable
> kernel bug.

Actually, it seems that if shmget is trying to get more than 2GB, it
will fail regardless of shmmax. When I backed shared_buffers down to
1980MB, PostgreSQL was able to start as long as shmmax is >= 2GB
(which I verified with 2GB+1MB, 3GB, and 8GB). I'm off to file a
report now.
--
Kirk Strauser