Processor Power Management via Cache Hit Rate and Idle Time Prediction
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Solution Overview
Problem
Existing processor technologies face challenges in reducing power consumption while minimizing performance degradation when entering and exiting low power modes, particularly due to cache refill requirements.
Innovation Solution
An application processor with a cache utilization management circuit and power management circuit that generates a power control signal based on cache hit rates and expected idle time to determine a power state level, controlling cores and caches accordingly to optimize power usage and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the processor enters a low power mode to reduce power consumption, then power consumption is reduced, but performance degradation occurs after exiting the low power mode due to cache refill requirements
Solution Approach 1:
The patent applies preliminary action by predicting the idle time before the processor actually enters low power mode. The power management circuit compares the predicted idle time with a threshold to determine whether entering low power mode will cause performance degradation. This allows the system to make informed decisions about power state transitions, avoiding entries that would result in unacceptable performance loss after cache refilling.
Solution Approach 2:
The patent implements feedback by using cache hit rate as a key parameter in the power management decision process. The power management circuit monitors cache performance metrics and uses this feedback to dynamically adjust power state decisions. When cache hit rates indicate that refilling would significantly impact performance, the system adjusts its low power mode entry strategy accordingly, creating a closed-loop control system that balances power consumption and performance.
2Productivity
If the processor stays in active mode to maintain performance, then performance is maintained, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the power state flexible and adaptive rather than fixed. The power management circuit dynamically adjusts the processor's power state based on real-time conditions including predicted idle time, cache hit rates, and performance requirements. This allows the system to transition between active and low power modes optimally, consuming less power when conditions permit while maintaining performance when needed.
Solution Approach 2:
The patent uses parameter changes by monitoring key parameters such as cache hit rate and idle time prediction to make power management decisions. By tracking these parameters and comparing them against thresholds, the system can intelligently determine when to enter or exit low power modes, optimizing the balance between power consumption and performance maintenance.
3Reliability
If the cache capacity is increased to reduce cache misses, then cache hit rate improves, but device complexity and power consumption increase
Solution Approach 1:
The patent applies preliminary action by predicting idle time before power state transitions occur. This prediction mechanism allows the system to determine in advance whether entering low power mode would result in unacceptable performance degradation, thereby avoiding unnecessary cache refilling operations and their associated power consumption and complexity overhead.
Solution Approach 2:
The power management circuit autonomously monitors cache performance metrics and makes independent decisions about power state transitions without requiring external intervention. This self-service capability allows the system to optimize its own power consumption and performance balance based on real-time cache hit rate monitoring and idle time prediction.
Data Source
AI summary
An application processor including at least one core, at least one first cache respectively connected to the at least one core, the at least one first cache associated with an operation of the at least one core, a second cache associated with an operation of the at least one core, the second cache having a storage capacity greater than the first cache, a cache utilization management circuit configured to generate, a power control signal for power management of the application processor based on a cache hit rate of the second cache; and a power management circuit configured to determine, a power state level of the application processor based on the power control signal and an expected idle time, the power management circuit configured to control the at least one core, the at least one first cache, and the second cache based on the power state level may be provided.