[maker-devel] maker low cpu utilization

[Christian Meesters]

Dear maker-developers,

As a computational scientist of our local HPC-Team, I recently installed 
maker and its tools.

We encountered a most peculiar problem: Distributed over 2 nodes, 64 
cores each (AMD OPT6272 "bulldozer"), all started processes take up ~20 
% of the possible CPU whilst the node show a full load of processes. 
Amongst this 20 % there is some system overhead (~4%).

We then wrote a little wrapper / submission script, such that the 
ctl-Files were altered and all reference input is copied unto ramdisks 
(each node provides the same path, there are then 2 copies of each 
reference file, prior to starting maker). Still no change - IO is not a 
bottleneck, here.

I then wanted to trace individual PIDs, but they are frequently 
changing. However, I saw > 170 instances ps concurrently running and the 
same amount of 'sh'.

Only augustus should about 100% CPU usage, all other (except maker 
itself) showed lower usage.

Have you ever experienced something similar and could perhaps provide a 
pointer to the cause? Could this perhaps be related to the nature of the 
input data (can some input data cause frequent switches of processes and 
therefore OS scheduler overhead)?

Thanks a lot in advance,
Best regards,
Christian Meesters

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Dr. Christian Meesters
Johannes Gutenberg-Universität Mainz
Zentrum für Datenverarbeitung
Anselm-Franz-von-Bentzelweg 12
55099 Mainz

tel. +49 (0)6131 39 26397

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