Re-Driver Power State Control for Low-Latency PCIe Links
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Solution Overview
Problem
As computing systems become more complex, the interconnect architecture to couple and communicate between components also increases in complexity to meet bandwidth requirements, but existing solutions struggle with balancing high performance and power efficiency, especially in diverse market segments like servers and mobile ecosystems.
Innovation Solution
The implementation of retimers and re-drivers in interconnect architectures, such as PCIe, to extend channel lengths and manage power consumption by inferring link states and setting corresponding power states, allowing for efficient power management without sacrificing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If re-driver devices operate in active mode to maintain signal integrity and low latency, then performance and responsiveness are improved, but power consumption increases
Solution Approach 1:
The re-driver device dynamically transitions between operational modes (active, intermediate, low-power) based on link traffic conditions. The device adjusts its power state in real-time, switching to lower power modes during idle periods while maintaining active state during data transmission to preserve performance characteristics.
Solution Approach 2:
The device changes operational parameters by transitioning between defined power modes with distinct electrical characteristics. Each mode represents a different parameter state with specific power consumption and latency characteristics, allowing the system to optimize based on current workload requirements.
2Use of energy by moving object
If re-driver devices are placed in low power modes to reduce power consumption, then energy efficiency is improved, but latency increases and performance deteriorates
Solution Approach 1:
The re-driver device performs preliminary actions by transitioning to intermediate power modes before entering deep low-power states. This staged approach allows the device to prepare for power reduction while maintaining the capability for rapid wake-up, thus minimizing latency penalties when returning to active state.
Solution Approach 2:
The device maintains continuous monitoring and control capabilities even in low-power modes, allowing for rapid transition back to active state when traffic is detected. This continuity ensures that the device can quickly resume full functionality without significant latency interruption.
3Use of energy by moving object
If intermediate power modes are implemented to balance power consumption and latency, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The power management system is segmented into distinct operational modes (active, intermediate, low-power) with clearly defined transition conditions. This segmentation simplifies control logic by providing discrete states rather than continuous adjustment, making the system easier to manage despite multiple power levels.
Solution Approach 2:
The device implements feedback mechanisms that monitor link traffic conditions and automatically adjust power state accordingly. This closed-loop control reduces the complexity of manual power management by allowing the system to self-regulate based on real-time traffic patterns and performance requirements.
Data Source
AI summary
An apparatus, such as a re-driver, can include a receiver port coupled to a first link partner across a first link; a transmitter port coupled to a second link partner across a second link; and a power management (PM) controller implemented in hardware. The PM controller can detect a PM control signal, determine a PM state for the apparatus based on the PM control signal, and cause the apparatus to enter the PM state. The apparatus can transmit electrical signals to the second link partner based on the PM state. The PM management control signal can include a clock request, an electrical idle, a common mode voltage, or other electrical signal indicative of a PM link state change of a link partner coupled to the re-driver.