20030609: freebsd tuning for things like shared memory

>From:  "Mike Schmidt" <address@hidden>
>Organization:  UCAR/Unidata
>Keywords: 200306091657.h59GvRLd029618 McIDAS-XCD FreeBSD shared memory

Mike (with CC to Mark Tucker of Lyndon State),

re: shared memory tuning on FreeBSD

>sysctl -A
> and
>man sysctl.conf

Since the shared memory parameters are only read when
the system goes from single user to multi user mode, I added the setting
of shared memory max to /etc/sysctl.conf on one of our FreeBSD
machines (FreeBSD emo.unidata.ucar.edu 4.7-STABLE FreeBSD 4.7-STABLE):

# $FreeBSD: src/etc/sysctl.conf,v 1.1.2.3 2002/04/15 00:44:13 dougb Exp $
#
#  This file is read when going to multi-user and its contents piped thru
#  ``sysctl'' to adjust kernel values.  ``man 5 sysctl.conf'' for details.
#
kern.ipc.shmmax=536870912

and then rebooted.  After it came back up, things look like what was
expected:

/local/ldm% sysctl -A | grep shm
kern.ipc.shmmax: 536870912
kern.ipc.shmmin: 1
kern.ipc.shmmni: 192
kern.ipc.shmseg: 128
kern.ipc.shmall: 8192
kern.ipc.shm_use_phys: 0

Thanks for the tuning help!

Tom

>From address@hidden Tue Jun 10 08:41:27 2003

Tom,

One clarification -- while the file /etc/sysctl.conf is read only once
as you specified, many of the kernel tunables can be set on the fly
thus averting a reboot.  I'd make the change to /etc/sysctl.conf and
then make the changes to the running kernel, one at a time;

 sysctl kern.ipc.shmmax=536870912

mike

>From address@hidden Tue Jun 10 12:21:32 2003

> >sysctl -A
> > and
> >man sysctl.conf
> 
> Since the shared memory parameters are only read when
> the system goes from single user to multi user mode, I added the setting
> of shared memory max to /etc/sysctl.conf on one of our FreeBSD
> machines (FreeBSD emo.unidata.ucar.edu 4.7-STABLE FreeBSD 4.7-STABLE):
> 
> # $FreeBSD: src/etc/sysctl.conf,v 1.1.2.3 2002/04/15 00:44:13 dougb Exp $
> #
> #  This file is read when going to multi-user and its contents piped thru
> #  ``sysctl'' to adjust kernel values.  ``man 5 sysctl.conf'' for details.
> #
> kern.ipc.shmmax=536870912

Tom, 
This seems to work as advertised.  Thanks.

-- 
Mark Tucker
Meteorology Dept. Systems Administrator
Lyndon State College
http://apollo.lsc.vsc.edu
address@hidden
(802)-626-6328