Polling Loop Management in Data Processing Apparatus
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Solution Overview
Problem
In data processing systems, the repeated polling of completion flags by the main processing unit to determine task completion by subsidiary units leads to significant power consumption and bus contention, especially in low-power systems.
Innovation Solution
The main processing unit enters a power saving mode after a threshold number of polls if the task is not completed, and a notification from the subsidiary unit wakes it up upon task completion, using existing interrupt paths for efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main processing unit continuously polls the completion field to determine task completion, then the task completion detection is reliable, but power consumption increases significantly
Solution Approach 1:
The patent implements periodic polling with a threshold mechanism - the main processing unit polls the completion field a limited number of times (threshold) before entering power saving mode. This transforms continuous polling into periodic action with built-in limits, reducing power consumption while maintaining acceptable reliability for task completion detection.
Solution Approach 2:
The patent introduces a feedback mechanism where the subsidiary processing unit actively notifies the main processing unit when the task is completed. This feedback loop allows the main processing unit to exit power saving mode and check completion status without continuous polling, resolving the contradiction between reliable detection and low power consumption.
2Reliability
If the main processing unit repeatedly polls the completion field, then task completion is detected accurately, but bus contention increases
Solution Approach 1:
The patent limits polling to a threshold number of attempts before entering power saving mode, transforming continuous polling into periodic action. This reduces the frequency of bus access requests, thereby decreasing bus contention while maintaining adequate detection accuracy through the threshold mechanism.
Solution Approach 2:
The notification mechanism from the subsidiary processing unit provides feedback that eliminates the need for continuous polling. Once the task is completed, the subsidiary unit sends a notification to the main processing unit, allowing the bus to be released from continuous polling-related contention.
3Use of energy by moving object
If the main processing unit enters power saving mode after threshold polls, then power consumption is reduced, but response time to task completion increases
Solution Approach 1:
The patent implements a feedback mechanism where the subsidiary processing unit notifies the main processing unit upon task completion. This allows the main processing unit to exit power saving mode quickly upon receiving the notification, minimizing the time loss while maintaining power savings during the polling phase.
Data Source
AI summary
A data processing apparatus and method are provided for managing polling loops. The data processing apparatus comprises a main processing unit and a subsidiary processing unit operable to perform a task on behalf of the main processing unit. The subsidiary processing unit is operable to set a completion field when the task has been completed and the main processing unit is operable to poll the completion field in order to determine whether the task has been completed. If on polling the completion field a threshold number of times the main processing unit determines that the task has not been completed, the main processing unit is operable to enter a power saving mode. The subsidiary processing unit is operable, when the task has been completed, to cause a notification to be issued on a path interconnecting the main processing unit and the subsidiary processing unit. The main processing unit is arranged, upon receipt of the notification to exit the power saving mode. This provides a particularly efficient technique for managing a polling loop within the data processing apparatus.