Re: SHMMAX seems entirely broken in OS X 10.4.2

Tom,

On 8/29/05 5:18 PM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Has anyone been able to set kern.sysv.shmmax above 4MB at all in latest
> OS X? I just spent a while trying what seemed every possible
> permutation of setting up /etc/sysctl.conf and editing /etc/rc directly,
> and it just fails (symptom: sysctl shows shmmax as -1, and Postgres
> cannot start).
>
> Grrr. Apple's been pretty lame about this from day one, but at least
> it's been possible to do it one way or another.
>
> (Curiously, it seems you can now change shmall after bootup in 10.4.2,
> but that's not much help when you can't change shmmax.)

Yes - it's very strange, I've had the same experience though I finally found
that setting SHMMAX and SHMALL to the same values, namely 268435456, seems
to work out fine.

I don't have a hypothesis as to why that value works though. I suspect that
equal values of all sizes would work, though I stopped trying when I found
this pair and it worked on multiple machines.

- Luke