Adding CPU to a unix box--added capacity.
- From: "Zhu,Chao" <zhuchao@xxxxxxxxx>
- To: oracle-l <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 2 Nov 2007 22:32:07 +0800
hi,
Does anyone have experience on adding new CPU to a existing box, like
upgrade from 8CPU to 16 CPU for example.
I am curious about two things;
1. How many CPU usage% drop do we expect? Like previously it is running at
50% CPU usage, typically will it drop to 25%? or something like 30%? To ask
the same question from another view, is , how much capacity we add to the
box? 16CPU box = 1.X(?) of a 8CPU box. Assuming same archtecture/OS. (same
cpu count server in different architecture may have different processing
power?)
Would be nice if you can share with your experience (like on
solaris/aix/hp etc). That's kind of typical server scalability.
2. Can we say, CPU_USED_BY_THIS_SESSION (stat in oracle) ~~
Unix_CPU_COUNT * USER_MODE_CPU% (vmstat usr column)? I did couple of compare
in my database, they look pretty close.
Does anyone ever thinking about have such a formular: it could be very
fun.
CPU_USED_BY_THIS_SESSION = X*logical_reads + Y*physical_reads + Z*sorts + A
* executions + B * redo_size + C * Latch_Spins+ .......?
by the way, anyone like the book"forecasting oracle performance"?
--
Regards
Zhu Chao
www.cnoug.org
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