On 01-09-16 13:06, Christof Koehler wrote:
"The only changes, users see when using the select/cons_res plugin, are
that jobs can be co-scheduled on nodes when resources permit it."
which taking [2] and manpage of sched.conf (OverSubscribe defaults to
"NO") into account means that in your configuration only jobs from
different partitions/queues can share a node.
Incorrect: jobs from one partition can share a node.
Now assume that there is only a single partition, which I think we would
prefer ad hoc. Then:
1. The default (select/linear, OverSubscribe=NO) is always exclusive. So the
job of course gets billed for the whole resources of a node.
Correct.
2. With a single partition select/cons_res and OverSubscribe=YES must be
simultaneously set so that jobs can share nodes. A user may allow other jobs
on a node allocated to his job by explicitely setting "--shared", in which case
only the actually allocated resources are billed to each different job on that
node. If he does not share the full resources are billed to him. The option
"--exclusive" is never needed.
Incorrect.
It's like this:
"select/cons_res" enables splitting of the resources (CPUs) between jobs
(so multiple jobs run on a node, each with dedicated resources). Only
the dedicated resources are billed. With "--exclusive" the whole node is
dedicated (and billed) to one job.
"OverSubscribe=FORCE" (or "OverSubscribe=YES" with "--shared") enables
sharing of the resources (CPUs) between jobs (multiple jobs run on the
same CPU, using time-sharing). A job is billed for the time it used the
dedicated resources. With "--exclusive" the whole node is dedicated
(and billed) to one job.
4. Only if OverSubscribe=FORCE is set on the partition the argument
"--exclusive" would make sense to prevent the default sharing of nodes.
With "--exclusive" all resources of the node would be billed to the
exclusive job automatically, right ?
Correct.
Best,
Robbert
--
Robbert Eggermont Intelligent Systems
r.eggerm...@tudelft.nl Electr.Eng., Mathematics & Comp.Science
+31 15 27 83234 Delft University of Technology
