Help needed please !!!

Robert G. Brown rgb at phy.duke.edu
Fri Jan 5 12:44:44 EST 2001


On Fri, 5 Jan 2001, Jared Hodge wrote:

> I have a dumb idea, or at least a dumb suggestion.  You say your problem
> involves a lot of iterations that you want to execute in parallel.  If
> you don't need to complete one iteration before beginning the next, you
> could very easily write a shell script to farm out the iterations to
> different processors and combine the results.  This could be your
> parallel "executable".  If this is the case (the "Embarrassingly
> Parallel" that RGB was talking about), then you could use a very
> advanced timing routing, "date" or something like that.  This probably
> isn't the case, though, since I doubt you would be asking for help if it
> were.  The problem is that if it isn't, you have to speed up every
> iteration of the loop through parallelism, something that may not be
> easy if the number of iterations is very large since you'll lose some
> time just waiting on communication because of network latency.  So if at
> all possible, go with Embarrassingly parallel.  Keep it simple.  Hey I
> told you this was a dumb idea, that's why they call it embarrassingly
> parallel.

You are absolutely correct (and this isn't dumb at all, if the code will
work that way), except that an even easier approach is to install MOSIX
and just run N copies all at once as if your local system had N CPUs.
Well, I don't know if it is easier or not -- a simple process
distribution shell script is pretty easy, and installing and configuring
MOSIX isn't quite so simple for a novice.  But it makes for a better,
more userproof cluster when you're done and is much cooler besides.

MOSIX is more or less designed to manage job distribution and load
balancing for embarrassingly parallel applications that don't do
anything too complicated with I/O and have a large run time:startup time
ratio.

   rgb

>
> Krishna Prasad wrote:
> >
> > Hello anyone,
> >
> >           I am doing my Btech Final year project in clustering.
> > I have gone through various projects given in beowulf site and Still I
> > coudn't make out the basic idea of how to split a job into parallely
> > executably form.  I plan to do my project on linux.
> >            What I plan to do is to split a process involving lot of
> > iterations into parallelly executable form and execute in the different
> > nodes of the cluster.  Please someone guide in simple terms as to how to
> > split the process or where to find the information about it.  Can it be
> > completed within 2 months time as it is my limit. Which language is suitable
> > for this?  What program or job can be used as input for this?
> >
> >           Also tell me how could I show the time taken for execution when a
> > process is executed serially and in a cluster.
> >           What we have is 3 nodes with lan connection in our college lab
> > each of having a  pentium processor with linux loaded in them.
> >
> > Please reply soon as my time is limited.
> >
> > Thanks in advance.
> > My email addresses are: sita_krish at hotmail.com and
> > sita_krish at rediffmail.com.
> > krishna prasad
> >
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>

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu




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