*: =EnteredCurrentState= - resets to the current time when the slot leaves "Drained" state - but also when the STARTD is restarted or each time the negotiator matches the slot and =NEGOTIATOR_INFORM_STARTD= is true (which is the default prior to 8.3.7).
*: =ExpectedMachineGracefulDrainingCompletion= - when this value is < time(), it represents the time at which the slot was fully drained - either because a drain state ran to completion or because the there were simply no jobs running on the slot or any children. when this value is > time() it represents the projected completion time of draining.
-So a policy that won't match non-multicore jobs for 2 negotiation cycles on recently drained slots could be:
+We can use one of these two attributes to trigger a policy that will match only multi-core jobs for N negotiation cycles on "recently drained" slots:
+*This is the preferred policy - use this policy if you use the defrag daemon*
{code}
+ # This knob must be set in the negotiator's configuration. it prevents
+ # slots from going into matched state, which is works fine and is necessary
+ # to make the $(StateTimer) trigger only when we leave draining state.
NEGOTIATOR_INFORM_STARTD = false
-IsntUnmatchedPSlot = PartitionableSlot=!=true || State=="Matched"
+
+ # A job counts as multicore when it requests 4 or more core, or when
+ # it has already matched to a slot that has less than 4 cores.
IsMulticore = RequestCpus >= IfThenElse(Cpus<4,1,4)
-OnlyMulticoreInterval = $(NEGOTIATOR_INTERVAL:60)*2
+ # We want to insist on multicore jobs for about 2 negotiation cycles
+OnlyMulticoreInterval = 2*$(NEGOTIATOR_INTERVAL:60)
+ # This is already defined in the default config, included for here for clarity
StateTimer = (time() - EnteredCurrentState)
+ # Ignore the policy for non p-slots
+IsntUnmatchedPSlot = PartitionableSlot=!=true || State=="Matched"
OnlyMulticoreJobsAfterDrain = $(IsntUnmatchedPSlot) || $(IsMulticore) || $(StateTimer) > $INT(OnlyMulticoreInterval)
@@ -23,16 +33,24 @@
The policy says that for 2 negotiation cycles after the STARTD starts up or leaves draining state, the slot should only match jobs that want at least 4 cores. Once the slot has less than 4 available Cpus remaining, it will match single-core jobs. We only want this portion of the START expression to be evaluated by the Negotiator, which is what the $(IsntUnmatchedPSlot) sub-expression does.
-An alternate policy using =ExpectedMachineGracefulDrainingCompletion= would be:
+Note for 8.2 and earlier versions: change =$INT(OnlyMulticoreInterval)= to =$(OnlyMulticoreInterval)=
+
+
+*Alternate policy that triggers whenever the p-slot fully drains for any reason - but doesn't work at all if draining is only partial*
+
+This policy using =ExpectedMachineGracefulDrainingCompletion= triggers the preference for multi-core automatically whenever a p-slot has no child d-slots, but, it reverts back to matching any job as soon as there are child d-slots.
{code}
+ # A job counts as multicore when it requests 4 or more core, or when
+ # it has already matched to a slot that has less than 4 cores.
IsMulticore = RequestCpus >= IfThenElse(Cpus<4,1,4)
+ # We want to insist on multicore jobs for about 2 negotiation cycles
OnlyMulticoreInterval = $(NEGOTIATOR_INTERVAL:60)*2
+ # How long has it been since the p-slot was fully drained.
+ # note that if the result is < 0, draining is in the future.
DrainStateTimer = (time() - ExpectedMachineGracefulDrainingCompletion)
OnlyMulticoreJobsAfterDrain = PartitionableSlot=!=true || $(IsMulticore) || $(DrainStateTimer) > $INT(OnlyMulticoreInterval) || $(DrainStateTimer) < 0
START = $(START) && ( $(OnlyMulticoreJobsAfterDrain) )
{endcode}
-
-This policy will match single-core jobs only very slowly once the supply of multi-core jobs runs out, and it requires that the p-slot be fully drained in order to trigger the preference for multicore jobs. The first policy only requires that the drain state be canceled before the preference triggers.
