Re: Can you limit number of CPUs

Hi Lisa,

There are 2 ways to do this successfully. One is to use processor sets, which are available starting in Solaris 2.6. These allow you to set aside a group of processors and then move processes into that set. No processes will run on those cpus except for the ones in the set and no processes in that set will run on any other cpus. See the "psrset" man page for how to set them up. This is a very easy way to partition a large number of cpus into subsets.

Creating, modifying and deleting processor sets can be done while things are running safely, so you can move cpus/processes into and out of processor sets as you want. This does need to be done as "root".

Also, the processor set a process is in is inherited, so you can (for example) put the oracle listener into a processor set and all new connections will also be in that set.

This is much better than binding processes to cpus (pbind) because the granularity is better.

See
http://www.sunworld.com/sunworldonline/swol-05-1998/swol-05-perf.html for more information.

A second way is to use the new (in Solaris 7) Solaris Resource Manager (SRM). This allows you to set up ways of sharing a machine where a percentage is dedicated to each subset of processes you choose to set up. Check out the blueprint at: http://www.sun.com/blueprints/0899/solaris5.pdf for some more information.

The cpu_count init.ora parameter is only used to set the size of various arrays within the SGA and won't do what you want. I wouldn't recommend altering it for this.

Hope this helps.

Dave Miller
Sun Microsystems, Inc.

>Date: Thu, 14 Sep 2000 09:31:00 -0800
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>X-Comment: Oracle RDBMS Community Forum
>X-Sender: Lisa Yttri <lyttri_at_execpc.com>
>From: Lisa Yttri <lyttri_at_execpc.com>
>Subject: Can you limit number of CPUs
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>Hi all -
>
>I am wondering if there is a way to limit the number of CPUs used by
>oracle on a unix machine (Sun Solaris in particular). If so, is this
>done through oracle or through unix. I have been told that it is
>possible with Solaris version 2.7, however my unix sa says it is not
>possible to do.
>
>Thanks in advance -
>
>Lisa Yttri
>Sr. DBA
>CNH Global
>Racine, Wisconsin
>
>--
>Author: Lisa Yttri
> INET: lyttri_at_execpc.com
>
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Received on Mon Sep 18 2000 - 14:32:20 CDT