[gridengine users] Reservations and parallel environments
richard.ems at cape-horn-eng.com
Fri May 25 10:14:20 UTC 2012
On 05/25/2012 11:51 AM, William Hay wrote:
>> We have a group of nodes with 12 slots.
>> We submit there parallel jobs requesting 4 or 12 slots.
>> We defined 2 PEs allocating 4 or 12 slots and associated to that group
>> of nodes in one queue.
> What do you mean be PE allocating 4 or 12 slots. You have 4 or 12 in
> the allocation rule. Or the
> slots field
I mean that "allocation_rule" is set to 4 or 12.
>> Is this expected behavior or are we doing a configuration error? Or is
>> it a bug? Or a feature?
> It depends somewhat on what else is going on. If the 4 slot jobs are
> shorter they might be getting
> in via backfill. Alternatively there might be jobs of higher
> priority than your 12 slot jobs eating all the reservations
> for other purposes. Fourthly the reservation behavior can sometimes
> be less than optimal when selecting where to run.
All jobs are being started with the same s_rt, so no backfill should be
And no, there are no jobs with higher priority eating the reservations.
> I'd recommend enabling the schedule log file and taking a look at what
> is happening.
I already enabled it. My first observations show me that the job asking
for 12 slots gets a reservation on a node running also a 12 slot job.
Later, when a 4 slot job finishes, a new 4 slot job starts on that 4
empty slots. I would have expected the node with that 4 empty slots to
get reserved ...
But thinking more on it ... perhaps because the 3 jobs J_4 -
started on a 12 slots node N1 - got started at different times, the last
one started could have been started *after* another job J4_12 running on
12 slots on node N2.
So job J3_4 will end *after* J4_12 - since both have equal
default_duration - and therefore N2 gets reserved and N1 starts another
Jn_4 4 slots job when one of J_4 finishes ...
Can anyone understand what I am trying to understand and explain in
these two last sentences? 8)
Many thanks again,
Richard Ems mail: Richard.Ems at Cape-Horn-Eng.com
Cape Horn Engineering S.L.
C/ Dr. J.J. Dómine 1, 5º piso
Tel : +34 96 3242923 / Fax 924
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