# Scheduling overhead

The fixed cost of dispatching a task and returning its result. When it approaches the cost of the task body, adding parallelism stops helping.

Source: https://university.eugo.io/glossary/scheduling-overhead

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A fixed cost per task, which is why task size matters more than task count. A task taking a millisecond spends most of its life being scheduled; batching a hundred of them into one changes the ratio decisively.

## Related terms

- [Batching](https://university.eugo.io/glossary/batching) — Grouping several small units of work into one task so that scheduling overhead does not dominate the time spent doing useful work.
- [Partition](https://university.eugo.io/glossary/partition) — One independently processable chunk of a dataset. Partition size is the main lever on how well a workload parallelizes.
- [Scheduler](https://university.eugo.io/glossary/scheduler) — The component on the head node that decides which compute node runs each task, honoring the resources that task requested.