If problem size grows with processor count, achievable speedup scales nearly linearly, unlike Amdahl's fixed-size case.
Gustafson's 1988 correction to Amdahl: in practice bigger machines get used on bigger problems, not the same problem faster, so the pessimistic bound rarely binds.
In practice
- A rendering farm doubled in size does not render the same frame twice as fast; it renders twice as many frames, which is what the studio wanted.
- A team that doubles headcount does not halve the delivery date, but it does take on twice the caseload, which is usually the actual goal.
- Further reading
- Wikipedia
- Subject
- Technology & Software
- Essay
- The curves, the limits and the laws of software