[Mauiusers] 8GB RAM limit when using NODEALLOCATIONPOLICY MINRESOURCE?

Lech Nieroda lnieroda at gmail.com
Wed Nov 11 07:29:29 MST 2009


Dear users and developers,

we have a heterogeneous cluster where nodes have 16GB and 64GB RAM,
our maui version is 3.2.6p21.
Although the NODEALLOCATIONPOLICY MINRESOURCE is set, jobs are
sometimes assigned to the larger nodes even though their resources
could be satisfied by a smaller node.

I've taken a quick look into the source code and it seems like growing
blocks of memory sizes are compared to corresponding node resources
and after some additional checks the right nodes are selected. The
block sizes vary between 64 and 8192 (probably MB), see
src/moab/MSched.c, lines 1180+
Which is probably the reason why nodes with more than 8GB free memory
are perceived as equal by the MINRESOURCE checking routine...

Is this going to be fixed? Is there another approach that might work?

Regards,
Lech


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