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Computational Model
- Unit cost for
- any instruction on O(log(n))-bit words
- Read/write a single memory location from an infinite memory
- The cost measure: time complexity
variant: Parallel RAM (PRAM) model
- is the main model of parallel execution in the OpenMP framework
- In addition to RAM instructions, you can also use
in parallelandparallel forinstructions.
mergesort(A, lo, hi):
if lo < hi:
mid = ⌊lo + (hi - lo) / 2⌋
fork mergesort(A, lo, mid) // process (potentially) in parallel with main task
mergesort(A, mid, hi) // main task handles second recursion
join
merge(A, lo, mid, hi)
- For all computations, draw a DAG
- A->B means that B can be performed only when A has been finished
- Work: the total number of operations
- Span (depth): the longest length of chain
Last modified 2yr ago