|
midrange.com
Sorry, Steve
I reread your note and realized that I misunderstood what you've said in
your note...
Yes, if CPU chip is the same, then very CPU bound program with a tight loop
(it's important - cache!) should perform the same regardless of CPW rating.
To ensure tight loop, do not use BIFs/subroutines/procedures etc.
Alexei Pytel
Disclaimer:
Opinions exressed here are entirely of my own and may or may not
represent my employer's position.
Alexei
Pytel/Rochester/IBM To: MIDRANGE-L@midrange.com
@IBMUS cc:
Sent by: Subject: Re: how is system
geared down?
owner-midrange-l@mi
drange.com
05/11/2001 10:42 AM
Please respond to
MIDRANGE-L
You misintrepret my words.
I did *not* say that *this* test in RPG will run with the same speed even
if number of repetitions is increased.
What I said was that since in this test the function is applied to the same
constant string every time, the smart compiler *may* eliminate this loop
and replace it with a single statement.
for example (in pseudocode):
for i = 1 to 1000000
x = 5;
is equivalent to a single statement
x = 5;
I did *not* say that RPG compiler can do this - I am not familiar enough
with it to make such statements.
But I did see similar setups used to demonstrate how Java program can run
100 times faster then equivalent RPG program.
This does not have very much relation to real life, because one rarely does
this kind of things in real applications - I hope.
About IBM comissars - I do not represent IBM in any way.
I think I should start include this statement in all my notes now:
Disclaimer:
Opinions exressed here are entirely of my own and may or may not
represent my employer's position.
Best regards
Alexei Pytel
"Pessimist is nothing but a well-informed optimist"
"Steve Richter"
<srichter@AutoCoder To:
<MIDRANGE-L@midrange.com>
.com> cc:
Sent by: Subject: Re: how is
system geared down?
owner-midrange-l@mi
drange.com
05/10/2001 11:31 PM
Please respond to
MIDRANGE-L
nice link to the power pc site.
In my view, speculating on this subject is worthwhile because it increases
technical understanding of the system.
I think the next step is to test alexei's assertion that a very cpu bound
pgm, say an rpg pgm that counts to 1 trillion, will execute in the same
amount of time on as400's with very different cpw ratings but the same cpu.
Alexei may himself be geared down in what he is allowed to say by the
commisars at ibm, but I would be very suprised if what he does say is not
true.
Steve
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