RE: Binding a process to a CPU .

Hi Shreepad,

I would strongly support Steve "Guru" Adams in not binding Oracle processes to CPU unless they have real-time priority. The problem is this : Although you may save on context switching, you are necessarily telling the process that it can only use one particular CPU even if others are available. What this means is that (unless it has real-time priority) the bound process *cannot* kick out another process that is holding the CPU and is executing some code that does not require it to context switch (i.e. it is not requesting I/O). If the other process was a CPU bound job, it will not relinquish the CPU until it finished it's time slot - a series of such jobs will effectively take away the gains that you obtain by saving on context switches.

Liken this to going to a particular counselor (for whatever advise) - you don't need to explain your woes everytime since he or she already knows your case (i.e. no context switching). However, you may *possibly* have to wait for a long time in case another 'chatty' counselee (is there such a word?) is occupying your counsellor (i.e. a CPU intensive process) and will not get out unless kicked out due to expiration of the time slot.

In short: Processor binding works (when supported by the OS) well *only* for CPU bound tasks not for a CPU-I/O combination-type process such as the Oracle backgound processes. And before I quit : YMMV.

Hth,
John Kanagaraj

PS: Haven't I heard of you at the Revealnet pipeline?

>-----Original Message-----
>From: Steve Adams [mailto:steve.adams_at_ixora.com.au]
>Sent: Tuesday, May 22, 2001 6:50 AM
>To: Multiple recipients of list ORACLE-L
>Subject: RE: Binding a process to a CPU .
>
>
>Hi Shreepad,
>
>Please see http://www.ixora.com.au/q+a/cpu.htm#15_10_1999.
>
>@ Regards,
>@ Steve Adams
>@ http://www.ixora.com.au/
>@ http://www.christianity.net.au/
>
>
>-----Original Message-----
>Sent: Tuesday, 22 May 2001 22:16
>To: Multiple recipients of list ORACLE-L
>
>
>
>
>Hi,
>I wish to test Parallel Query .
>
>HP-UX 10.2 K Class machines , 4 CPU 2 GB RAM , Oracle 7.3.4.4
>
>When the background processes are created , Can I bind ( a slave
>process related to Parallel query server) them to a specific CPU . ?
>Is this Possible .?
>Has anyone checked this out .? Any Problems.
>
>
> shreepad.
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
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>Author: Shreepad Vaidya
> INET: Shreepad.Vaidya_at_alltel.com
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: John Kanagaraj
  INET: john.kanagaraj_at_hds.com

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