Jasper Lake EDS Vol1


ID 633935
Date 01/01/2021
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Enhanced Intel SpeedStep® Technology

Enhanced Intel SpeedStep® Technology enables OS to control and select P-state. The following are the key features of Enhanced Intel SpeedStep® Technology:

  • Multiple frequency and voltage points for optimal performance and power efficiency. These operating points are known as P-states.
  • Frequency selection is software controlled by writing to processor MSRs. The voltage is optimized based on the selected frequency and the number of active processor IA cores.
    • Once the voltage is established, the PLL locks on to the target frequency.
    • All active processor IA cores share the same frequency and voltage. In a multi-core processor, the highest frequency P-state requested among all active IA cores is selected.
    • Software-requested transitions are accepted at any time. If a previous transition is in progress, the new transition is deferred until the previous transition is completed.
  • The processor controls voltage ramp rates internally to ensure glitch-free transitions.
Note: Because there is low transition latency between P-states, a significant number of transitions per-second are possible. All of Processor Cores must be in the same P-state at any given time.