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On 3/13/19 11:31 AM, Lars Henrik Sowa
wrote:
Hi
all,
Currently
I do not understand why Memory is in there with a negative
sign. According to the documentation memory is “The amount
of RAM in MiB in this slot. For static slots, this value
will be the same as in TotalSlotMemory. For a partitionable
slot, this value will be the quantity remaining in the
partitionable slot.”. In our case this is equal to
TotalSlotMemory as well as TotalMemory as we only have one
slot per machine. However if I understood this correctly
this would mean that with the default value,
NEGOTIATOR_PRE_JOB_RANK would prefer machines with less
memory over ones with more memory. Is this correct? If I now
actually want to match machines with more memory first I
just would have to turn the – memory into a + memory?
The idea for the negative signs in front of the memory and cpu,
is this: Typically a job requests at least a certain amount of
memory and cores. Given there may be many slots which match a
given job, the smallest one that meets the request leaves larger
slots available for other jobs which may require more. When the
negotiator run, it examines one job at a time (from the user with
the best user priority). The negotiator doesn't know anything
about any other jobs that might be coming next, so this policy
tries to minimize resource fragmentation.
-greg
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