Microprocessor IPC Reduction for Power Saving
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Solution Overview
Problem
Microprocessors in low workload conditions waste power even in their lowest performance running state due to idle time, as they cannot further reduce operating frequency without transitioning to a sleeping state, which is typically initiated by the operating system.
Innovation Solution
The microprocessor implements IPC-reduction power saving actions such as in-order execution, scalar instruction issuance, serial cache access, and reduced instruction formatting, which are autonomously triggered by predetermined conditions to conserve power without entering a sleeping state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the microprocessor operates in the lowest performance running state, then power consumption is reduced, but the microprocessor still wastes power due to idle time and cannot reduce frequency further
Solution Approach 1:
The patent changes the operational parameters of the microprocessor by reducing the instructions-per-clock (IPC) rate through architectural modifications such as in-order execution, scalar instruction issuance, and reduced instruction formatting. This allows the processor to consume less power during idle periods without transitioning to sleep states, effectively resolving the contradiction between maintaining running state productivity and reducing power consumption.
Solution Approach 2:
The microprocessor dynamically adjusts its execution mode based on workload conditions. When idle time is detected at the lowest performance state, the processor transitions to a reduced IPC mode, enabling adaptive power management that optimizes the balance between power consumption and computational throughput in real-time.
2Speed
If the microprocessor maintains running state at lowest frequency, then it can respond quickly to workloads, but power consumption remains high due to idle execution
Solution Approach 1:
The patent implements periodic monitoring of workload conditions and alternates between normal execution mode and reduced IPC mode. The processor periodically checks for idle conditions and transitions to power-saving execution modes during idle periods, then returns to full performance when workloads arrive, creating a rhythmic pattern of operational states that reduces average power consumption while maintaining responsiveness.
3Use of energy by moving object
If the microprocessor enters sleeping state to reduce power, then power consumption decreases significantly, but the operating system must initiate the transition which adds complexity
Solution Approach 1:
The microprocessor autonomously determines when to transition to reduced IPC mode based on internally monitored workload conditions. The processor self-manages the transition to and from power-saving states without requiring operating system intervention, eliminating the software control complexity associated with traditional C-state transitions while achieving similar power savings.
Data Source
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AI summary
A microprocessor includes functional units and control registers writeable to cause the functional units to institute actions that reduce the instructions-per-clock rate of the microprocessor to reduce power consumption when the microprocessor is operating in its lowest performance running state. Examples of the actions include in-order vs. out-of-order execution, serial vs. parallel cache access and single vs. multiple instruction issue, retire, translation and/or formatting per clock cycle. The actions may be instituted only if additional conditions exist, such as residing in the lowest performance running state for a minimum time, not running in a higher performance state for more than a maximum time, a user did not disable the feature, the microprocessor supports multiple running states and the operating system supports multiple running states.