SHMMAX in kernel config

[Charles Sprickman]

Howdy,

I recently upgraded an old box running 4.6.2 to 4.9-p4, and found that
afterwords, Postgres was hanging due to kern.ipc.shmmax being way too low
(4096 bytes, or one page).

The line in the kernel config (as confirmed by LINT) was this:

options         SHMMAXPGS=8192  # max amount of shared memory pages (4k)
options         SHMALL="(SHMMAXPGS*PAGE_SIZE+1)"
options         SHMMAX="(SHMMAXPGS*PAGE_SIZE+1)"

Thinking perhaps this was no longer valid, I tried again by doing the math
myself, but I got the same result; kern.ipc.shmmax=4096.

For now I'm just setting this in sysctl.conf, but I'm curious as to what
has changed, or what I'm doing wrong.

Thanks,

Charles

--
Charles Sprickman
spork at inch.com