# I/O-bound

A workload whose runtime is limited by reading and writing data rather than by calculation. Adding workers to an I/O-bound job adds waiting, not throughput.

Source: https://university.eugo.io/glossary/io-bound

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Establish the ratio of read time to compute time before concluding a workload will benefit from more workers.

## Related terms

- [Compute-bound](https://university.eugo.io/glossary/compute-bound) — A workload whose runtime is limited by how fast calculations can be performed. Adding workers to a compute-bound job generally makes it finish sooner.
- [Columnar format](https://university.eugo.io/glossary/columnar-format) — A file format that stores values grouped by column rather than by row, so a reader can fetch only the fields it needs.
- [Object storage](https://university.eugo.io/glossary/object-storage) — Storage reachable by every node in a cluster. Inputs must live here, or in workspace storage, rather than on one machine’s local disk.
- [Profiling](https://university.eugo.io/glossary/profiling) — Measuring where a program actually spends its time, before deciding what to optimize.