Re: Tuning Semaphores on Solaris

From: Mladen Gogala <mgogala_at_adelphia.net>
Date: Sat, 10 May 2003 22:15:30 GMT
Message-Id: <pan.2003.05.10.22.15.28.543782@adelphia.net>

On Sat, 10 May 2003 21:15:36 +0000, Hans Forbrich wrote:

> Strong suggestion install the Oracle Enterprise Manager, then the Diagnostic &
> Tuning Pack & let them help you decide on the appropriate changes to the
> parms.
>
> [For others ... first you get the initial install up as described in the Install
> Guide with the minimum Semaphores & Shared Memory. Remeber, depending on OS,
> sema and shm parameters frequently require a reboot.
>
> OEM is included in your license but the Packs are extra $ option. I especially
> fnd Tuning Pack worth the extra $ but YMMV
>
> /Hans

You need 1 semaphore / oracle process + several for fixed overhead. Here are results from my Linux workstation:

$ sudo ksh
# ipcs -s

Semaphore Arrays -------- key semid owner perms nsems status 0x951e5eec 98304 oracle 640 154

# ps -fu oracle

UID        PID  PPID  C STIME TTY          TIME CMD
oracle    1627     1  0 18:03 pts/0    00:00:00 /oracle/product/9.2.0/bin/tnslsnoracle    1656     1  0 18:03 ?        00:00:00 ora_pmon_o9i
oracle    1658     1  0 18:03 ?        00:00:00 ora_dbw0_o9i
oracle    1660     1  0 18:03 ?        00:00:00 ora_lgwr_o9i
oracle    1662     1  0 18:03 ?        00:00:00 ora_ckpt_o9i
oracle    1664     1  0 18:03 ?        00:00:00 ora_smon_o9i
oracle    1666     1  0 18:03 ?        00:00:00 ora_reco_o9i
oracle    1668     1  0 18:03 ?        00:00:00 ora_cjq0_o9i
oracle    1670     1  0 18:03 ?        00:00:00 ora_qmn0_o9i
oracle    1672     1  0 18:03 ?        00:00:00 ora_s000_o9i
oracle    1674     1  0 18:03 ?        00:00:00 ora_d000_o9i
oracle    1676     1  0 18:03 ?        00:00:00 ora_d001_o9i
# ps -fu oracle|wc -l
     13

#
$ sqlplus /

SQL*Plus: Release 9.2.0.3.0 - Production on Sat May 10 18:07:16 2003

Connected to:
Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production With the Partitioning option
JServer Release 9.2.0.3.0 - Production

SQL> show parameter processes

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes                      integer     1
db_writer_processes                  integer     1
job_queue_processes                  integer     2
log_archive_max_processes            integer     2
processes                            integer     150

SQL> As you can see, I have 4 semaphores + the value of "processes" parameter.

I would allocate 50 semaphores + the value of "processes" parameter. That would include the "JOB_QUEUE" processes, background system processes, shared servers, dispatchers, DBSNMP "intelligent agent", occasional RMAN or two and PQ processes. Once again, my OS is RH Linux 8.0 with certain modifications:

$ cat /etc/issue
Red Hat Linux release 8.0 (Psyche)
Kernel \r on an \m

$
$
$ uname -a

Linux medo.adelphia.net 2.4.20 #5 Sun Apr 27 02:16:17 EDT 2003 i686 athlon i386 GNU/Linux
$

-- 
Mladen Gogala
Software is like sex, it is better when it is free.
Linus Torvalds

Received on Sat May 10 2003 - 17:15:30 CDT