RE: question about cpu usage (fwd)
- From: ryan_gaffuri@xxxxxxxxxxx
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 22 Oct 2004 22:43:38 +0000
dont see any harm in putting this on oracle-l. cary probably just didnt do a
reply to all.
the chart is very useful.
-------------- Forwarded Message: --------------
From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
To: <ryan_gaffuri@xxxxxxxxxxx>
Subject: RE: question about cpu usage
Date: Fri, 22 Oct 2004 20:06:54 +0000
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
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-----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?
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