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<font face="serif">On your last paper many of you complained about
the fact that the queues were so full that you got terrible
timings. </font><font face="serif"><font face="serif">I suspect
that what was really going on was that people were timing code
at the same time others were doing development work. </font>That
problem is going to be exacerbated on this project because you are
timing multiprocessor code. We have an easy way to alleviate
that problem that mimics what is done at national supercomputing
centers.<br>
<br>
1. DO your development work on COBRA. Cobra should have the same
compilers. Assuming you have your ssh keys set up on cobra you
should be able to just clone your repository over there, get
everything like you want it and then push it back to gitlab and
clone it on zeus. The only difference is that the atlas
libraries that I tuned are in /pub/pounds/ATLAS/lib on cobra so
you would have to make that small change to your makefile if you
want to compile against them.<br>
<br>
2. People using the zeus processors for Bear Day should be done
(they are still using the cluster, but not the zeus processors).
This means that zeus should be cleared out for testing. <br>
<br>
3. ONLY DO YOUR TIMINGS on ZEUS using the BATCH QUEUS and make
sure to specify the number of processors your need in your batch
script. If you need all 8 processors for up to two hours then you
would have the following line in your PBS file<br>
<br>
#PBS -l nodes=1:zeus:ppn=8,walltime=2:00:00<br>
<br>
If you don't need all 8 processors then please don't request all
of them as that blocks others from using the queues. It is also
imperative that you -- for the sake of your classmates -- never
use more processors that you actually requested. If you request 4
processors in the batch queue then don't run a program that uses
more than 4 threads.<br>
<br>
4. I recommend that you include your PBS job scripts in your
repository -- that will make it very easy for you to go back and
make modifications if needed.<br>
<br>
<br>
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<pre class="moz-signature" cols="72">--
Andrew J. Pounds, Ph.D. (<a class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 (478) 301-5627
<a class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
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