PCI Express Link Energy Management Preventing Data Loss
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Solution Overview
Problem
PCI Express link energy management results in data loss due to interruption of current data sending and receiving when the physical layer state machine transitions from a normal working state to a recovery state.
Innovation Solution
A method and device for dynamically adjusting the rate and/or bit width of a PCI Express link by stopping data sending, clearing the master enable bit of a configuration space command register, performing adjustments, and resuming data sending to prevent data loss during link energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the physical layer state machine enters recovery state from normal working state to adjust link rate or bit width, then energy consumption is reduced, but data transmission is interrupted causing data loss
Solution Approach 1:
The patent applies preliminary action by stopping data sending before the link adjustment is performed. The PCI express device clears the master enable bit of the configuration space command register of the opposite end device, which prevents the opposite end from sending new data before the link parameters are changed. This ensures that no data is lost during the transition, as all in-flight data is completed before the adjustment takes effect.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that data transmission continues uninterrupted in terms of data integrity. Although the link parameters change, the data flow remains continuous because all data sent before the adjustment is guaranteed to be transmitted completely, and the master enable bit is restored after adjustment to resume normal operations without data loss.
2Loss of energy
If the link bandwidth is reduced by lowering transmission rate or bit width, then power consumption decreases, but the service requirement may not be satisfied when traffic increases
Solution Approach 1:
The patent implements dynamics by making the link bandwidth adjustable based on traffic conditions. The PCI express device can dynamically change the link rate and/or bit width by controlling the physical layer state machine transitions. When traffic is low, the link operates at lower bandwidth to save power; when traffic increases, the link can be adjusted to higher bandwidth to meet service requirements, creating a dynamic adaptation to workload conditions.
Data Source
AI summary
Embodiments of the present invention disclose a PCI express device, and a link energy management method and device. The method includes: obtaining, by a first device, adjustment information for performing adjustment processing on a current rate and/or bit width of a PCI express link; stopping, by the first device, data sending, and clearing a master enable bit of a configuration space command register of a second device at an opposite end of the link, so that the second device stops data sending after current data sending is finished; performing, by the first device, adjustment processing on the rate and/or bit width of the link according to the adjustment information; resuming, by the first device, the data sending, and resetting the master enable bit, so that the first device and the second device send and receive data again at a rate and/or bit width that is obtained after the adjustment processing.