Re: FreeBSD and large shared_buffers a no-go?

[Kirk Strauser <kirk@xxxxxxxxxxxx>]

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

Kirk Strauser <kirk@xxxxxxxxxxxx> 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