Re: Tunning FreeeBSD and PostgreSQL

>>>>> "SH" == Stephen Howie <showie(at)centwire(dot)com> writes:

SH> Richard-
SH> That was very helpfull Thanks!
SH> I still would like some guidance on tunning FreeBSD (shmmax and shmmaxpgs).
SH> Do I need to even touch these settings?

Here's what I use on FreeBSD 4.7/4.8. The kernel settings don't hurt
anything being too large for the SHM values, since they are limits,
not anything pre-allocated (from my understanding). These settings
allow for up to 100,000 shared buffers (I currently only use 30,000
buffers)

options SYSVMSG #SYSV-style message queues

# only purpose of this box is to run PostgreSQL, which needs tons of shared
# memory, and some semaphores.
# Postgres allocates buffers in 8k chunks, so tell Postgres to use about
# 150 fewer than SHMMAXPGS/2 buffers to leave some room for other Postgres
# shared memory needs.
options SYSVSHM #SYSV-style shared memory
# Maximum number of shared memory pages system wide.
options SHMALL=262144
# Maximum size, in pages (4k), of a single System V shared memory region.
options SHMMAXPGS=262144

# only need semaphores for PostgreSQL
options SYSVSEM #SYSV-style semaphores
# Maximum number of System V semaphores that can be used on the system at
# one time.
options SEMMNI=32
# Total number of semaphores system wide
options SEMMNS=512
# Maximum number of entries in a semaphore map.
options SEMMAP=256

Also, in /etc/sysctl.conf I put

# need lots of files for database
kern.maxfiles=8000
# tuning for PostgreSQL
kern.ipc.shm_use_phys=1

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