PCIe Command Prefetch and Dynamic Power Management
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Solution Overview
Problem
Current PCIe systems face inefficiencies in command fetching and power management, leading to increased latency and power consumption, particularly during idle states, as they rely on traditional methods that do not effectively detect and respond to idle link conditions.
Innovation Solution
The implementation of a PCIe system and method that registers a lightweight notification (LN) and prefetches commands, along with advanced power management techniques that detect idle states and dynamically change power modes to reduce power consumption, such as transitioning to lower power states like L1 and L1.2 when no commands are being processed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional PCIe command fetching methods are used, then the system maintains simple operation, but command fetching time increases and system productivity decreases
Solution Approach 1:
The patent implements command prefetching by having the PCIe device proactively fetch commands from host memory before they are actually needed for execution. The device monitors the command queue and initiates prefetch operations when the queue is empty or has few commands, thereby reducing idle waiting time and improving command fetching efficiency without requiring fundamental changes to the PCIe protocol
2Speed
If the PCIe link remains in active state to ensure quick command response, then command fetching speed is maintained, but power consumption increases during idle periods
Solution Approach 1:
The patent implements dynamic power management by transitioning the PCIe link between different power states (L0, L1, L1.2) based on actual workload conditions. The system monitors command queue status and link activity, dynamically adjusting the link state to balance between power savings during idle periods and quick response capability when commands are pending, thereby resolving the contradiction between speed and power consumption
3Use of energy by moving object
If the PCIe link transitions to low power states during idle periods, then power consumption is reduced, but latency increases when transitioning back to active state
Solution Approach 1:
The patent reduces latency after power state transitions by implementing preliminary actions: keeping the command queue pre-filled with upcoming commands before transitioning to low power states, and maintaining buffer readiness in the PCIe device. This ensures that when the link wakes from L1/L1.2 states, commands are already available for immediate processing, minimizing the effective latency experienced by the system
4Productivity
If lightweight notification (LN) registration is implemented to reduce command fetching time, then productivity improves, but device complexity increases
Solution Approach 1:
The patent extracts and implements only the essential Lightweight Notification (LN) registration mechanism from the full PCIe notification framework, selectively enabling LN for command queue status notifications while maintaining other traditional notification methods for completion events. This selective extraction improves command processing efficiency through faster queue status awareness while avoiding the complexity overhead of implementing the entire PCIe notification suite
Data Source
AI summary
The present technology relates to an electronic device. A computing system may include a host and a peripheral component interconnect express (PCIe) device connected the host through a link. The host comprises a host memory and a storage device driver. The host memory may store information on a first target command to be executed in the PCIe device. The storage device driver may provide the first target command to the host memory and a notification message indicating that the first target command is stored in the host memory to the PCIe device. The PCIe device may request the host memory to register an address of the host memory in which a second target command to be executed in the PCIe device is stored through a preset protocol.