[GE users] Multithreading and resource consumption

Bevan C. Bennett bevan at fulcrummicro.com
Wed Feb 21 00:22:01 GMT 2007


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Situation: We have some applications that (either by default or sometimes by
user-configuration) run multi-threaded and use up more than a single CPU worth
of computational resources.

I figured that creating a default parallel environment seemed like the correct
answer for this, so a job known to spawn two active threads could use "-pe multi
2" and get issued two slots, preventing it from stepping on, or being stepped on
by, other jobs on the same system.

At first these jobs weren't running at all, claiming "no suitable queues", until
I figured out that consumables specified with "-l" appear to get multiplied by
the number of nodes requested, so "qsub -pe multi 4 -l mem=2G" would look for a
system with 4 open slots and mem=8G (2Gx4), not 4 slots and mem=2G.

The problem has now arisen, however, that some of these applications have a
limited number of licenses available. We've been tracking the licenses through
SGE as well, but a multi-threaded "-pe multi 4" job doesn't need to take up 4
licenses (and, in fact, can't, because they don't exist). Is there any way to
over-ride this resource multiplication?

FWIW, the job in question needs 1 "standard" and 1 "enable multithreading"
license, no matter how many threads we tell it to spawn.

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