[torqueusers] question about default fifo scheduler

Garrick Staples garrick at usc.edu
Tue Jan 31 16:59:42 MST 2006

On Tue, Jan 31, 2006 at 10:28:21AM -0800, Alexander Saydakov alleged:
> Hi!
> Does anyone know how does the default fifo scheduler determine the
> availability of the nodes in is_ok_to_run_job()? Particularly I would like
> to know if a node (cpu) can become available in a middle of a scheduling
> cycle?
> My reasoning is as follows: A scheduling cycle begins (in my configuration)
> with sorting of queues according to priority and sorting of jobs within
> queues according to priority. Then the scheduler considers those sorted jobs
> one by one and calls is_ok_to_run_job(). If a free slot can become available
> any time during this process, that means any job can happen to run
> regardless of priority. Is this possible? I think that it is what I see. If
> so how Maui does that?

I'm not sure about pbs_sched, but it is not possible in maui/moab.  They
query pbs_server for all job info, all node info, and then make
scheduling decisions on that information.  There are no repeated queries
during a scheduling cycle.

I'd assume pbs_sched works the same way, but someone else will have to
check the code to confirm.

Garrick Staples, Linux/HPCC Administrator
University of Southern California
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