Dynamic Cache Way Power Control for Processor Energy Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cache memories in processors consume excessive power due to their larger size, which is necessary to accommodate increasing performance demands, and existing power management techniques either fully power down caches when idle or rely on static thresholds, leading to inefficiencies in power usage and performance.
Innovation Solution
Implementing a dynamic power management system that selectively powers down or powers up cache ways based on workload demands, using a power management unit to adjust cache size by controlling which cache ways are active, allowing the processor to remain active while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cache size is increased to accommodate performance demands, then processor performance is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic cache way disabling that adapts the cache configuration in real-time based on processor activity. The system monitors processor idle states and dynamically disables cache ways during idle periods while maintaining full cache functionality during active periods, resolving the contradiction between maintaining performance and reducing power consumption.
Solution Approach 2:
The system changes operational parameters by modifying the number of active cache ways based on processor state. When the processor enters an idle state, the system reduces the active cache capacity by disabling specific cache ways, thereby changing the power consumption parameter while maintaining sufficient performance during active operation.
2Use of energy by moving object
If cache is fully powered down to reduce power consumption, then power usage decreases, but performance degradation occurs
Solution Approach 1:
Instead of fully powering down the cache, the system applies partial action by disabling only a subset of cache ways while leaving others active. This partial disabling reduces power consumption sufficiently during idle states while maintaining enough cache capacity to avoid significant performance degradation when the processor becomes active.
Solution Approach 2:
The system dynamically adjusts the number of active cache ways based on processor activity rather than using a static full-power-down approach. This dynamic adjustment ensures that sufficient cache capacity remains available to prevent performance degradation while still achieving power savings during idle periods.
3Device complexity
If static threshold methods are used for cache power management, then implementation simplicity is improved, but power usage efficiency deteriorates
Solution Approach 1:
The system implements feedback mechanisms by monitoring processor activity states and using this information to dynamically control cache way disabling. This feedback loop enables the system to respond to actual processor needs, improving power usage efficiency compared to static threshold methods while maintaining reasonable implementation complexity through structured monitoring and control.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and apparatus for dynamically controlling a cache size is disclosed. In one embodiment, a method includes changing an operating point of a processor from a first operating point to a second operating point, and selectively removing power from one or more ways of a cache memory responsive to changing the operating point. The method further includes processing one or more instructions in the processor subsequent to removing power from the one or more ways of the cache memory, wherein said processing includes accessing one or more ways of the cache memory from which power was not removed.