Scheduling

Scheduling – First Principles
Thread(T1) cpu – sync – I/O – kernel scheduler

FCFS, Highest static priority, highest dynamic priority, thread whose memory contents are in the cpu cache

Memory hierarchy refresher
cpu – l1-chache (1-2 cycles)- l2-chache(~10cycles) -> memory(~100 cycles)

cache affinity scheduling
T1 descheduled, t1 rescheduled
interventing threads on P1

FCFS: Ignores affinity for fairness
Fixed proccessor: Ti always on P fixed
Last processor: Ti on P last

Minimum Intervening: Ti -> Pj ^ Imi

implementation issues
queue based
-global que
-affinity-based local queues

Ti’s priority = BPi + agei + affinityi
-Determines poisition in the queue

Performance
Figures of merit
-throughput -> system centric
-response time -> user centric
-variance -> user centric

Multicore multithreaded processors