Notes about Intel Enhance SpeedStep Technology
本文将mark下Intel Enhance SpeedStep Technology的相关notes。
Overview
Enhance Intel SpeedStep Technology enables operating system to control and select P-state, it allows the processor to lower the speed when it is in idle or low workload, this will allow the system to save power consumption.
Key features
- 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 model-specific registers (MSRs).
The voltage is optimized based on the selected frequency and the number of active processor IA cores.
- All active processor IA cores share the same frequency and voltage. In a multicore 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(处理器内部控制电压升降速率，确保无毛刺平滑转换).
- Because there is low transition latency between P-states, a significant number of transitions per-second are possible.
Spec
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