Re: shared memory settings on MAC OS X

Maximilian Tyrtania <mty(at)fischerappelt(dot)de> writes:
> I am trying to increase the amount of shared memory on my Mac OS 10.4
> machine (i have 5 GB RAM installed), but without too much success.

Weird, those same exact settings work fine for me. How up-to-date
is your 10.4.x installation? The relevant part of /etc/rc in mine is

if [ -f /etc/sysctl-macosxserver.conf ]; then
awk '{ if (!index($1, "#") && index($1, "=")) print $1 }' < /etc/sysctl\
-macosxserver.conf | while read
do
sysctl -w ${REPLY}
done
fi
if [ -f /etc/sysctl.conf ]; then
awk '{ if (!index($1, "#") && index($1, "=")) print $1 }' < /etc/sysctl\
.conf | while read
do
sysctl -w ${REPLY}
done
fi

sysctl -w kern.sysv.shmmax=4194304 kern.sysv.shmmin=1 kern.sysv.shmmni=32 kern.\
sysv.shmseg=8 kern.sysv.shmall=1024

So one obvious gotcha would be if you have a
/etc/sysctl-macosxserver.conf file that sets 'em differently.

The gotchas I know about in this area are:

* The OSX kernel seems to lock down the shmem settings as soon as all
five have been correctly specified via sysctl. This is why the sysctl
done last in /etc/rc doesn't overwrite yours.

* It's fairly draconian about what "correctly specified" is --- notably,
at least some versions insist on shmmax being an exact multiple of the
page size. But the numbers you quoted look OK.

regards, tom lane