CPUs and architecture

Which model plots whether a program's performance is limited by compute throughput or memory bandwidth, using arithmetic intensity (operations per byte) on the horizontal axis?

  1. AAmdahl's law
  2. BThe roofline model
  3. CThe Poisson model
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Answer: B. The roofline model

In the roofline model, programs with low arithmetic intensity are capped by memory bandwidth (the sloped line), while those with high intensity are capped by the processor's peak compute (the horizontal line). The shape resembles a roof, hence the name, and it is used to decide how to improve performance.

  • A. Amdahl's law expresses the speedup limit caused by the non-parallelizable part.
  • B. Correct. It plots the limits of compute and memory bandwidth.
  • C. The Poisson model is used for yield calculations and the like.
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More CPUs and architecture questions

  1. What is the main purpose of pipelining in a CPU?
  2. What is the main purpose of cache memory?
  3. Which is a characteristic of a von Neumann computer?
  4. What is the main purpose of putting multiple processor cores on one chip (multicore)?
  5. Which is a characteristic of RISC (reduced instruction set computer)?