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Re: Upper limit on number of buffers?

From: "Joe Conway" <jconway2(at)home(dot)com>
To: "Alfred Perlstein" <bright(at)wintelcom(dot)net>, "mlw" <markw(at)mohawksoft(dot)com>
Cc: "Hackers List" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Upper limit on number of buffers?
Date: 2000-12-25 03:25:04
Message-ID: 033901c06e22$464d5330$0705a8c0@jecw2k1 (view raw or whole thread)
Lists: pgsql-hackers
> * mlw <markw(at)mohawksoft(dot)com> [001224 18:06] wrote:
> > This line works:
> > /usr/local/pgsql/bin/postmaster -N 32 -B 928 -i -S
> > -D/home/postgres/pgdev -o "-F -fs -S 4096"
> >
> > Where as this line:
> >
> > /usr/local/pgsql/bin/postmaster -N 32 -B 1024 -i -S
> > -D/home/postgres/pgdev -o "-F -fs -S 4096"
> >
> > does not.
> >
> > Any ideas?
> > I have 256M of memory, RedHat Linux 7.0, CVS version of Postgres as of a
> > couple days ago.
> I'm just going to guess that you need to consult your OS's
> documentation and figure out how to raise the amount of system V
> shared memory available.

I think Alfred is probably correct. I've run into this before myself. See
the following link:

The relevant section reads:


The default shared memory limit (both SHMMAX and SHMALL) is 32 MB in 2.2
kernels, but it can be changed in the proc file system (without reboot). For
example, to allow 128 MB:

$ echo 134217728 >/proc/sys/kernel/shmall
$ echo 134217728 >/proc/sys/kernel/shmmax
You could put these commands into a script run at boot-time.

Other parameters are sufficiently sized for any application. If you want to
see for yourself look into /usr/src/linux/include/asm-xxx/shmparam.h and

Hope this helps,


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