Re: How are CPU Speed and Overall CPW Related? -- MIDRANGE-L


I see that now you suspect that IBM is putting a horde of governors all
over the place.
This is not the case.

If your program uses little memory - it is not memory constrained - so
adding more memory will not change anything for it.
But if it requires lots of memory, and real memory is not big enough, and
parts of a program or data get paged in and out - then your application is
memory constrained. Adding more memory will reduce or eliminate paging
overhead and make your program run faster.

Same logic applies to disk constrained - 100 disk drives can perform more
disk accesses per second than 10 disk drives.
So if your application needs 1000000 disk accesses to complete, then on a
100 drive system it will finish faster than on 10 drive system.

That simple. And no need for governors...


Best regards
    Alexei Pytel
System Performance III
Dept XQK/006-2    Rochester, MN
(507) 253- 2867 or T/L 553-2867
Internet:  pytel@us.ibm.com  VM mail: IBMUSM07(PYTEL)

"If you have a fountain, turn it off. Fountain also needs a rest!"
Classical Russian aphorism.



                                                                                
                   
                    "Nathan M. Andelin"                                         
                   
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                    Sent by:                  Subject:     Re: How are CPU 
Speed and Overall CPW   
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                    drange.com                                                  
                   
                                                                                
                   
                                                                                
                   
                    04/30/2001 12:33 PM                                         
                   
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                    MIDRANGE-L                                                  
                   
                                                                                
                   
                                                                                
                   



Just thought of another related question.  The V4R4 Performance Planning
Guide characterizes the machine's maximum CPW rating as a figure that might
be constrained by memory and disk.  This may sound like a dumb question,
but
consider it in light of the fact that a 100 Mhz  machine runs a CPU bound
program faster than a 200 Mhz machine, as delineated in my previous post.
If I upgraded my machine from 320 MB Ram to the maximum 832 MB, would an
individual program run faster, even though the program used little memory?
Is there a governor on the CPU that might be adjusted by the addition of
memory?  Sorry if this sounds rediculous.

Thanks,

Nathan.


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