Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!emory!hubcap!"PBACAD::M_PAPRZYCKI"
From: "PBACAD::M_PAPRZYCKI"@UTPB.PB.UTEXAS.EDU
Newsgroups: comp.parallel
Subject: How much are you willing sacrifice.
Message-ID: <12935@hubcap.clemson.edu>
Date: 5 Feb 91 22:01:44 GMT
Sender: fpst@hubcap.clemson.edu
Lines: 30
Approved: parallel@hubcap.clemson.edu

In one of the recently received messages I found he following passage: 

   The first point I would make is that `efficiency' is very much less
   important to me than coding clarity. I am quite prepared to sacrifice
   half my CPU time if it makes the code easier to maintain. 

I probably have a idea, what Steven is talking about, however I am
not sure if this strong a statement is an appropriate one.

It seems to me that nobody wants to do anything in parallel if
his/hers problem does not require A LOT of time, or cen be an important
part of the problem, which itself requires A LOT of time, or .....
These are simple lessons that follow from Amdahls Law, and as
far as I remember are known under the name: Amdahl's Effect.
Even more general, parallelization MAKES SENSE only for really LARGE
problems.
If this is the case, then I really have problems with simple claims
like: I can sacrifice half of my CPU time, to make my code
looking nice. I would like to see when you try to tell this to somebody, 
who is running an application that takes about 12 hours to complete.
I do not believe that such a person will be happy with the message:

"I could have run your program in 3 hours, but I wanted your program
to look beautifully, so it requires 6 hours."

Summary:
	One should be very cautious in deciding what one wants to 
	sacrifice.

Marcin


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