Newsgroups: comp.parallel.pvm
From: Krishnan Subramaniam <krishnan@apple.com>
Subject: Re: Help: Hint on parallel application
Organization: Apple Computer, Inc.
Date: Fri, 09 Aug 1996 14:05:11 -0700
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Message-ID: <320BA807.24DA@apple.com>

> 
> We need to test our TransNet (Transputer-network made of
> 15 Pentiums with T9000-board in PCI-slot) to measure load and
> behaviour while running a parallel problem, written in PVM, on it.
> 
> We search a problem where we can change the factor of
> communication- against computeload.
>  
> Thank you for hints or references
> Roger Schoenthal

The simplest problem qould be sorting a randomly generated HUGE file
using varaitoins of Qsort or "tree based" sorting flows.
Fo eg. if you had a 3 level tree
                P00             ---> root
         P10           P11      ---> level1
     P20   P21       P22  P23   ---> level 2 (leaf nodes in my case).
   
The picture is not the greatest but I hope you get the point.
In this scenario the leaves of the tree read different portions of the 
file and sort their segment and sent it on upward.
Each of the upper levels sorts the 2 inflows from its children and 
passes on the sorted ouput upwards ... Until eventually
P00 starts getting input and starts writing out the completely sorted 
inpu. This may not be the most efficient way but its quite commn. 
intensive
and compute intensive (change the comparison function to do something 
heavy duty). By changing the size of messages exchanged between 
children --> parent we can effectively change the # of messages.
Also by changing the # of levels in the tree we can tune the ratio of 
compute to commn in the lower levels of the tree.

Hope I've presented the case clearly.

Sincerely,
Krishnan.

P.S.:
could you compile and post answers you get as this could be quite 
intersting to many people.
Thanks.

--
Krishnan Subramaniam
krishnan@apple.com

