Adaptive Processor Cache Bypass for Low-Locality Workloads
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Solution Overview
Problem
Processor-based devices experience memory access latency issues due to low cache hit rates, particularly in graphics workloads, leading to performance degradation and increased power consumption.
Innovation Solution
Implement an adaptive cache bypass mechanism that tracks cache result rates and restricts cache access when these rates fail to meet predefined thresholds, allowing direct access to higher-level caches or system memory, and periodically re-enables the cache to optimize performance and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cache memory is used to reduce memory access latency, then memory access speed is improved, but cache hit rate decreases for applications with low temporal and spatial locality
Solution Approach 1:
The patent implements dynamic cache configuration by monitoring cache hit rates and automatically adjusting cache enable/disable states based on real-time performance metrics. The system transitions from a static cache configuration to a dynamic one where cache parameters are continuously adjusted according to workload characteristics, allowing the cache to adapt between high-speed access mode and high-hit-rate mode based on actual application needs
Solution Approach 2:
The patent changes cache operational parameters (enable/disable state, associativity, pre-fetch settings) based on measured cache result rates. When the cache result rate falls below a threshold, the system modifies cache parameters by disabling the cache or adjusting its configuration, thereby transforming the cache from a fixed-parameter component to an adaptive one that optimizes performance based on real-time conditions
2Reliability
If cache access is restricted to improve cache hit rate, then cache effectiveness is improved, but memory access latency increases
Solution Approach 1:
The patent implements a feedback mechanism where cache performance is continuously monitored and used to control cache access behavior. The system measures cache result rates and uses this feedback to dynamically enable or disable cache access, creating a closed-loop control system that adjusts cache effectiveness based on actual performance outcomes, thereby optimizing the balance between cache hit rate and access latency
Solution Approach 2:
The patent makes cache access configuration dynamic by allowing real-time adjustment of cache enable/disable states based on monitored performance. The system can transition between restricting cache access (when hit rate is low) and allowing cache access (when hit rate is high), creating a dynamic access control mechanism that adapts to changing workload conditions to minimize latency while maintaining effectiveness
3Use of energy by stationary object
If cache is disabled to bypass low cache result rate, then power consumption is reduced, but cache hit rate decreases
Solution Approach 1:
The patent implements self-service by having the cache system automatically monitor its own performance and make decisions about its operational state without external intervention. The cache controller measures cache result rates and autonomously determines when to enable or disable the cache, creating a self-regulating system that optimizes power consumption based on actual cache effectiveness, thereby eliminating the need for manual configuration or external control
Data Source
AI summary
Providing adaptive cache bypass in processor-based devices is disclosed. In some aspects, a processor-based device comprises a processor that comprises a cache. The processor is configured to calculate a cache result rate based on a first one or more outcomes of a corresponding first one or more cache requests to a cache region of the cache during a sampling period. The processor is further configured to determine that the cache result rate fails to satisfy a cache result requirement. The processor is also configured to, responsive to determining that the cache result rate fails to satisfy the cache result requirement, restrict access to the cache region of the cache subsequent to the sampling period.