[GE users] preemption & scheduling

yarmond yarmond at gmail.com
Thu Feb 26 20:51:00 GMT 2009

I have been trying to set up preemption using Grid Engine 6.2, and have encountered a few problems. I am mostly following the directions given on this page:
under the third scenario. I have two queues set up, long.q and normal.q, where jobs in normal.q are allowed to preempt those in long.q. I have different problems with jobs, depending on whether they are using a PE or not. 

For jobs running in a PE set up for SMP jobs (using allocation rule $pe_slots), the problem I am having is that jobs submitted to normal.q are sometimes sent to a node already running a job in long.q, even when there are idle nodes available. I have tried changing the scheduler configuration to use "-slots" as the load_formula, but that seems to have no effect at all. On what basis is the scheduler choosing which node to allocate, and how can I affect that decision?

For jobs not running in a PE, setting load_formula to "-slots" or "slots" behaves predictably, but neither gives me the behavior that I actually want. If I have one node with 8 processors running a 8-processor job in long.q, and two idle nodes, I would prefer additional jobs in normal.q would fill one of the idle nodes, then the other. Using "-slots" causes jobs to alternate between the idle nodes, and using "slots" causes the preemptible job to be suspended while leaving the other two nodes idle. 

Is there any way to configure the scheduler to prefer to fill nodes (to leave room for SMP jobs) but not leave idle nodes while still allowing preemption? I can provide additional details about my configuration if needed. Any help in resolving these scheduling woes would be greatly appreciated.


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