Free Virtual memory lessonsVirtual memory · Stage 0 · Demand paging · Step 3
What a page fault costs
Calculate effective access time with page faults, and see why the fault rate must be tiny. About 12 minutes.
Memory access takes 100 ns and servicing a page fault takes 10 ms (10,000,000 ns). Roughly what fault rate keeps the slowdown under 10%?
- AFewer than one fault in a million references
- BFewer than one fault in a hundred references
- CFewer than one fault in two references
Show the answer
Fewer than one fault in a million references. 100 + p × 10,000,000 < 110 needs p < 0.000001.
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