Configurable Cache Controller Serial Lookup Power Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-core processing systems face challenges in efficiently managing cache memory access to balance performance and power consumption, particularly in reducing access/snoop bandwidth while conserving dynamic power.
Innovation Solution
An N-way set associative cache memory system with a configurable cache controller that performs cache lookups in parallel using N ways or serially using subsets of M ways, where M<N, to optimize access and reduce power consumption based on the system's power state and type of access requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cache lookups are performed on all N tag ways concurrently, then access bandwidth and latency are improved, but power consumption increases
Solution Approach 1:
The cache controller dynamically adjusts the lookup strategy between parallel and serial modes based on system state, enabling adaptive optimization of the trade-off between access speed and power consumption
Solution Approach 2:
The system changes the operational parameters of the cache controller by adjusting the degree of parallelism (from N-way parallel to serial) based on power state and access type, thereby optimizing performance under different conditions
2Use of energy by moving object
If cache lookups are performed serially on subsets of M tag ways, then power consumption is reduced, but access bandwidth and latency worsen
Solution Approach 1:
The cache controller dynamically switches between serial and parallel lookup modes depending on power state and access type, allowing the system to reduce power consumption when high performance is not critical
Solution Approach 2:
The system performs partial parallel lookups by processing subsets of M tag ways concurrently rather than all N ways, achieving a balance between power savings and acceptable access performance
3Adaptability or versatility
If the cache controller is configured to dynamically adjust lookup method, then adaptability is improved, but device complexity increases
Solution Approach 1:
The cache controller implements dynamic reconfiguration capability to switch between parallel and serial lookup modes based on system state, enhancing adaptability while managing complexity through state-based control logic
Data Source
AI summary
A cache system is configurable to trade power consumption for cache access latency. When it is desired for a system with a cache to conserve dynamic power, the lookup of accesses (e.g., snoops) to cache tag ways is serialized to perform one (or less than all) tag way access per clock (or even slower). Thus, for an N-way set associative cache, instead of performing a lookup/comparison on the N tag ways in parallel, the lookups are performed one tag way at a time. This take N times more cycles thereby reducing the access/snoop bandwidth by a factor of N. However, the power consumption of the serialized access when compared to ‘all parallel’ accesses/snoops is reduced.