From: Dave Cramer <pg@fastcrypt.com>
To: Brian Wipf <brian@shoptoit.ca>
Cc: pgsql-performance@postgresql.org
Subject: Re: shared_buffers > 284263 on OS X
Date: Sat, 18 Nov 2006 11:17:01 -0500
Message-ID: <82E59D2F-0946-4405-8F11-4CF5184A9399@fastcrypt.com> (raw)
In-Reply-To: <B242A585-E94C-4ECA-8FA9-DCE72E1D8838@shoptoit.ca>
References: <B242A585-E94C-4ECA-8FA9-DCE72E1D8838@shoptoit.ca>
Brian,
On 16-Nov-06, at 7:03 PM, Brian Wipf wrote:
> I'm trying to optimize a PostgreSQL 8.1.5 database running on an
> Apple G5 Xserve (dual G5 2.3 GHz w/ 8GB of RAM), running Mac OS X
> 10.4.8 Server.
>
> The queries on the database are mostly reads, and I know a larger
> shared memory allocation will help performance (also by comparing
> it to the performance of the same database running on a SUSE Linux
> box, which has a higher shared_buffers setting).
>
> When I set shared_buffers above 284263 (~ 2.17 GB) in the
> postgresql.conf file, I get the standard error message when trying
> to start the db:
>
> FATAL: could not create shared memory segment: Cannot allocate memory
> DETAIL: Failed system call was shmget(key=5432001,
> size=3289776128, 03600).
>
> shmmax and shmall are set to 4GB, as can be seen by the output from
> sysctl:
> hw.physmem = 2147483648
> hw.usermem = 1885794304
> hw.memsize = 8589934592
> kern.sysv.shmmax: 4294967296
> kern.sysv.shmmin: 1
> kern.sysv.shmmni: 32
> kern.sysv.shmseg: 8
> kern.sysv.shmall: 1048576
>
> Has anyone else noticed this limitation on OS X? Any ideas on how I
> might get shared_buffers higher than 284263?
My guess is something else has taken shared memory ahead of you. OS X
seems to be somewhat strange in how it deals with shared memory. Try
allocating more to shmmax ?
Dave
>
> Brian Wipf
> <brian@clickspace.com>
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings
>
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: pg@fastcrypt.com, brian@shoptoit.ca
Subject: Re: shared_buffers > 284263 on OS X
In-Reply-To: <82E59D2F-0946-4405-8F11-4CF5184A9399@fastcrypt.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox