CPUs and architecture

Approximately how many instructions per second can a processor with a 2 GHz clock and an average CPI (clocks per instruction) of 0.5 execute?

  1. A1 billion instructions
  2. B4 billion instructions
  3. C100 million instructions
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Answer: B. 4 billion instructions

There are 2×10⁹ clocks per second, and each instruction takes 0.5 clocks on average, so the number of instructions is 2×10⁹ ÷ 0.5 = 4×10⁹, or 4 billion. A CPI below 1 means multiple instructions are executed per clock, for example by a superscalar design.

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More CPUs and architecture questions

  1. If 90% of a program can be parallelized, what is the theoretical maximum speedup when it runs on an unlimited number of processors?
  2. Which scheme performs the same operation on multiple data items simultaneously with a single instruction?
  3. Which CPU configuration combines high-performance cores and power-efficient cores and uses them according to the workload?
  4. Which technique examines instruction dependencies and executes ready instructions in an order different from the program order to improve performance?
  5. Which CPU mechanism temporarily suspends the current task to give priority to handling requests such as those from external devices?