FW: question about cpu usage

["Cary Millsap" <cary.millsap@xxxxxxxxxx>]

I forgot to cc the list last Friday when I responded to this...


Cary Millsap
Hotsos Enterprises, Ltd.
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-----Original Message-----
From: Cary Millsap [mailto:cary.millsap@xxxxxxxxxx]=20
Sent: Friday, October 22, 2004 3:05 PM
To: 'ryan_gaffuri@xxxxxxxxxxx'
Subject: RE: question about cpu usage

Ryan,

Good question actually. It depends on how many CPUs are in there. If you
have a copy of "Optimizing Oracle Performance" handy, check out table =
9-3 on
page 260. What it says is that you can expect performance to vary
unpredictably on a 1-CPU machine when CPU utilization exceeds 50%. On a
2-CPU machine, the magic number is about 57.7%. On a 4-CPU machine, it's
66.5%. The table lists "knee in the curve" numbers for CPU counts =
ranging
from 1 to 128.

The whole section called "Behavior of M/M/m Systems" (pp254-266) should =
be
of interest to you.


Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

Upcoming events:
- Performance Diagnosis 101: 10/26 Toronto, 1/4 Calgary
- SQL Optimization 101: 10/18 New Orleans, 11/8 Dallas, 12/13 Atlanta
- Hotsos Symposium 2005: March 6-10 Dallas
- Visit www.hotsos.com for schedule details...


-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx =
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of ryan_gaffuri@xxxxxxxxxxx
Sent: Friday, October 22, 2004 2:56 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: question about cpu usage

I'm not a hardware guy or sys admin person so forgive me if this is a =
stupid
question. Leaving out all other variables(such as IO), should I expect
performance to be the same in a databse if the server it is riding at is =
at
90% cpu usages as opposed to 10%? since there would still be spare =
cycles?
Or is there a declining returns as you get closing to the maximum =
available
cpu usage?=20
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FW: question about cpu usage