Details
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Story
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Status: Resolved
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Minor
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Resolution: Fixed
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None
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None
Description
TaskScheduler makes an attempt to preempt already identified candidates through Preemptor when it fails to schedule a task. However, Preemptor currently evaluates only one candidate per invocation. A candidate may get vetoed at this point by scheduling filters. If a candidate fails validation the task group might get penalized by TaskGroups to give PendingTaskProcessor some time to find new preemption candidates; despite the fact that such a candidate may already exist in slotCache. This penalty can result in expiration of slotCache entries, hence slowing down the overall preemption process.
Consider modifying Preemptor so that it evaluates all existing preemption candidates before giving up. This improvement comes at the price of reduced scheduling throughput. However, in a near capacity cluster, reduced scheduling throughput is far more acceptable than failure to schedule critical production services.