H's job is not to choose whichever value returns first. It must choose a source that the permission and dirty-responsibility history justifies. Settle the source before comparing routes or latency.
Lesson | After it you can... |
|---|---|
Decide which source may answer in each settled state. | |
Compare an E holder with an M holder on a forwarded read, and the direct-to-reader variant. | |
Compare direct and H-buffered exclusive-permission transfers and what each costs. | |
Tell legally stale memory from a stale response. |
Suggested order: source, dirty response, route alternatives, then stale-data diagnosis.
No. The right source follows from the line's history and the pending transaction, not from arrival order. Returning stale memory sooner is a correctness failure.