Service-Curve Earliest Deadline scheduling
Result: SCED is optimal for meeting service curve guarantees
provided the server’s service curve is not concave.
Observation: SCED with GPS service-curves (straight line thru’ origin) == Virtual Clock scheduling
I.e., SCED supports a weaker form of fairness than PGPS (like PGPS’s hard-real-time guarantee)
Went from Virtual Clock to [P]GPS
Would like to go from SCED to something like [P]GPS
Two aspects of fairness:
- how to distribute excess bandwidth
- is a connection penalized later for getting excess bandwidth?
- VC/ SCED -- Yes
- we’d like -- No