Re: [Condor-users] priority groups and preemption

["Matt Hope" <matthew.hope@xxxxxxxxx>]

On 4/25/07, Jonathan D. Proulx <jon@xxxxxxxxxxxxx> wrote:
> On Wed, Apr 25, 2007 at 03:56:53PM +0100, Matt Hope wrote:
>
> :Higher RANK (as in startd rank) currently guarantees preemption.
>
> Ah, I was confused because there was nothing about RANK in the PEEMPT
> macro.
>
> I should probably RTFM on thsi one, but do jobs that have been
> preempted previously have any protection against being preempted
> again?

Not by default no

> I'm wondering how to protect long running jobs (in the vanilla
> universe) from being preempted and requeued in an infinite loop.
> Presumably this is considered and likely a bit more reading will clear
> it up...

Note that the UWSC macros used by default for several
startd/negotiation settings (notably PREEMPTION_RANK which governs
picking a job from a list of possible preemption candidates) are not
well suited to a predominantly vanilla universe workload.

The default is to preempt those jobs which have run the *longest*
(which in a checkpoint aware world would be fine since it would avoid
a single job 'dancing' over the execute nodes never getting any
progress) but that is exactl;y what you probably don't want if you are
running in vanilla mode.

here is a vanilla only world example for a dedicated calc farm machine:

# the machine is decated - no need for any suspend or machine sourced preempt
WANT_SUSPEND = FALSE
WANT_VACATE = FALSE
SUSPEND = FALSE
CONTINUE = FALSE
PREEMPT = FALSE

##  When to instantaneously kill a preempting job
##  (e.g. if a job is in the pre-empting stage for too long)
KILL = TRUE

# prefer to kick the shorter jobs unless there is a large differential
in the users priority
PREEMPTION_RANK = (EnteredCurrentState - CurrentRank) + RemoteUserPrio
PERIODIC_CHECKPOINT	= FALSE

PREEMPTION_REQUIREMENTS	= FALSE

# RANK can be whatever you want allowing for the fact that it always
triggers a preemption

# I am explicitly happy with the UWCS values for PRE/POST RANK
NEGOTIATOR_PRE_JOB_RANK = $(UWCS_NEGOTIATOR_PRE_JOB_RANK)
NEGOTIATOR_POST_JOB_RANK = $(UWCS_NEGOTIATOR_POST_JOB_RANK)

Hope these snippets help

Matt