15 January 2007
Lampson: Lazy and Speculative Execution
23
Speculative:
Branch Prediction
nThe
bet: Branch will go as predicted
oA big win in latency of later operations
oLittle cost, since otherwise you have to wait
nNeeds
undo if speculation fails
x
→ !S Þ !S; ~x → undo !S
nScheduling:
Predict from history
oSometimes get hints from programmer