Peripheral Processor Wait-for-Event Wake-Up Mechanism
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Solution Overview
Problem
Peripheral devices in computing systems face power consumption issues due to processors remaining idle but still consuming power, and existing wake-up mechanisms like interrupts introduce latency, limiting the frequency of entering low-power mode.
Innovation Solution
Implementing a wait-for-event mechanism in peripheral devices to manage processor power states, allowing for quick wake-up without latency, by using a management module to detect idle processors and signal events for low-power mode entry and exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a processor enters low-power mode to reduce power consumption, then power consumption is reduced, but wake-up latency increases due to interrupt handling requirements
Solution Approach 1:
An event detection mechanism acts as an intermediary between the external environment and the processor in low-power mode. The mechanism detects events (such as doorbell registers being written) and directly triggers processor wake-up without requiring full interrupt handling, thus reducing wake-up latency while maintaining power savings
Solution Approach 2:
The system performs preliminary actions by setting up event detection and wait-for-event instructions before the processor enters low-power mode. Event detection mechanisms are pre-configured to monitor specific conditions, and when events occur, they can immediately wake the processor without requiring complex interrupt processing, thereby reducing wake-up time
2Loss of time
If a processor remains idle but active to respond quickly to events, then wake-up latency is reduced, but power consumption increases
Solution Approach 1:
The processor dynamically transitions between active and low-power states based on workload conditions. By using wait-for-event instructions and event detection mechanisms, the processor can quickly switch to low-power mode when idle and wake up rapidly when events occur, optimizing the balance between power consumption and response time
3Reliability
If interrupt mechanisms are used for wake-up, then reliability of event response is improved, but wake-up latency increases due to interrupt handling overhead
Solution Approach 1:
The wake-up mechanism is segmented into two paths: full interrupt handling for complex events requiring software processing, and event-triggered wake-up for simple events that can be handled more quickly. This segmentation allows the system to maintain reliability through proper event handling while reducing latency for time-critical wake-up scenarios
Data Source
AI summary
A processor in a peripheral device can include a wait-for-event mechanism, through which the processor can enter low-power mode and be woken from lower-power mode with an event. Using an event, rather than an interrupt, allows the processor to wake without the latency incurred by an interrupt handling routine. In various implementations, the processor may be configured to execute a sequence of instructions that include a wait-for-event instruction. The wait-for-event instruction can be called when the processor is idle. The wait-for-event instruction may initiate a low-power mode for the processor, wherein the processor suspends executing the sequence of instructions. The processor may further be configured to receive, at an event input, an event signal. The event signal may cause the processor to exit the low-power mode and to resume executing the sequence of instructions from the point at which the processor suspended executing the sequence of instructions.