15 January 2007
Lampson: Lazy and Speculative Execution
22
Speculative:
Prefetching
nIn
memory, file systems, databases
nThe
bet: Prefetched data is used often enough
oto pay for the cost in bandwidth
oObviously
the cost depends on what other uses there are for the bandwidth
nScheduling
oFigure out what to prefetch
▬Take instructions from the program
▬Predict from history (like branch prediction)
oAssign priority