[Beowulf] Powersave on Beowulf nodes

Huw Lynes lynesh at cardiff.ac.uk
Mon Jun 23 02:25:00 PDT 2008

Eoin McHugh wrote:
> I don't run a daemon but I use the Torque prologue and epilogue to set
> the max and min power states using the /proc cpufreq interface before 
> and after jobs. This results in a power saving when a queued jobs are 
> waiting for additional nodes to free up. It's a measurably large 
> difference when the system is being drained prior to a downtime. Our 
> nodes are never shared beteen jobs making this easy to implement.

We've been looking at power-saving measures on our new cluster. I've 
gradually come around to the idea that a compute node only really has 
two modes of efficiency:
1) running flat out
2) switched off at the wall

In our first year of production we are unlikely to have jobs keeping the 
cluster full much of the time. So I'm considering writing something to 
watch the job queue and power down nodes that are not needed. The trick 
here being to work out some logic such that nodes aren't constantly 
being power-cycled. Obviously this isn't an option unless you have some 
form of lights-out control (e.g IPMI) on your nodes.


Huw Lynes                       | Advanced Research Computing
HEC Sysadmin                    | Cardiff University
                                 | Redwood Building,
Tel: +44 (0) 29208 70626        | King Edward VII Avenue, CF10 3NB

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