Power Management

Which describes CPU P-states?

  1. APerformance levels while the CPU runs, defined by combinations of frequency and voltage
  2. BHow deeply the CPU sleeps when idle
  3. CTypes of CPU package
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Answer: A. Performance levels while the CPU runs, defined by combinations of frequency and voltage

P-states divide a running CPU's frequency and voltage combinations into levels; higher levels are faster and use more power. The OS or the CPU's internal power-management circuitry switches P-states to match load (DVFS). Combined with C-states, which describe sleep depth, this lets the CPU run at a suitable speed when there is work and sleep deeply when there is none.

  • A. Correct. They correspond to DVFS levels.
  • B. That is a C-state.
  • C. It is not a package type.
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More Power Management questions

  1. When does "race to idle" (finishing work fast and then sleeping deeply) tend to save energy?
  2. What is the role of a governor, such as a cpufreq governor, that sets CPU frequency in Linux and other OSes?
  3. Which describes CPU turbo operation (such as Turbo Boost)?
  4. Which describes thermal throttling?
  5. Some CPU power limits let the chip run above the long-term average limit (close to TDP) for short periods. Why does this work?