From owner-freebsd-hackers  Fri May  3  0:38:15 2002
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Date: Fri, 3 May 2002 00:35:32 -0700 (PDT)
From: Patrick Thomas <root@utility.clubscholarship.com>
To: <freebsd-hackers@freebsd.org>
Subject: RFC on my SHM tunings for multiple jailed postgres...
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I have a large server that will be running ~24 jails, 8 of which will be
running their own postgres server.

Because of this fact:

By default, Postgres allocates 34 semaphores, which is over half the
default system total of 60.

I need to tune kernel SHM settings in order to even run the second
postgres, much less the other six.  So, this is what I have in my kernel,
and I appreciate any comments or suggestions regarding the
appropriateness:


(of course, by default, I have)

options         SYSVSHM                 #SYSV-style shared memory
options         SYSVMSG                 #SYSV-style message queues

(and the following is _all_ that I have added)

options         SHMMAXPGS=16384
options         SHMMAX="(SHMMAXPGS*PAGE_SIZE+1)"
options         SHMSEG=256
options         SEMMNI=384
options         SEMMNS=768
options         SEMMNU=384
options         SEMMAP=384


My references for this are:

http://www.us.postgresql.org/users-lounge/docs/7.1/admin/kernel-resources.html

http://groups.google.com/groups?q=freebsd+SEMMNI+postgres&hl=en&selm=01091023443406.73075%40prime.vsservices.com&rnum=7


All comments and suggestions appreciated !

--PT


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