Joint Prefetch Scheduler for Cache Lookup Latency Reduction
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Solution Overview
Problem
Traditional cache management techniques exhibit limitations in responsiveness and adaptability to varying workloads and data access patterns, affecting data retrieval performance in modern computing systems.
Innovation Solution
A joint scheduler is employed to jointly schedule prefetch and demand accesses, associating instructions with cache entries and tracking invalidation/eviction, enabling efficient data retrieval by reducing cache lookups and optimizing cache usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional cache management techniques are used, then cache structure is simple, but responsiveness and adaptability to varying workloads and data access patterns deteriorates
Solution Approach 1:
The patent merges prefetch scheduling and demand access scheduling into a single joint scheduler that handles both types of memory accesses uniformly. This integration allows the system to maintain a relatively simple cache structure while achieving improved responsiveness and adaptability through unified scheduling logic that can dynamically prioritize different access types based on workload characteristics.
Solution Approach 2:
The joint scheduler implements dynamic scheduling policies that adapt to varying workloads and data access patterns in real-time. The scheduler can dynamically adjust the priority and timing of prefetch operations versus demand operations based on observed access patterns, thereby improving adaptability without requiring complex static cache structures.
2Loss of time
If prefetch accesses are implemented to pre-load data, then data availability improves, but memory access latency increases due to additional cache lookups
Solution Approach 1:
The joint scheduler performs preliminary prefetch operations proactively before demand accesses are needed. By anticipating future data requirements and pre-loading data into the cache through coordinated prefetch operations, the system reduces actual data retrieval latency when demand accesses occur, while the unified scheduling prevents redundant lookups.
Solution Approach 2:
The joint scheduler uses feedback from prefetch hit/miss outcomes to dynamically adjust subsequent scheduling decisions. When prefetch operations successfully load data into cache, the scheduler recognizes this and adjusts future prefetch timing and intensity, thereby reducing redundant cache lookups and optimizing the balance between data availability and access latency.
3Ease of operation
If separate schedulers are used for prefetch and demand accesses, then scheduling control is precise, but device complexity and coordination overhead increases
Solution Approach 1:
The patent combines separate prefetch scheduling and demand access scheduling functions into a single joint scheduler entity. This merger eliminates the coordination overhead between multiple schedulers while maintaining precise control over both access types through unified scheduling logic that can prioritize and time operations appropriately.
Solution Approach 2:
The joint scheduler is designed as a universal scheduling entity that handles both prefetch and demand accesses through a single coordinated mechanism. This multi-functional approach simplifies the overall system architecture by eliminating the need for separate scheduler structures and their associated coordination interfaces, thereby improving ease of operation.
Data Source
AI summary
A joint scheduler adapted for dispatching prefetch and demand accesses of data relating to a plurality of instructions loaded in an execution pipeline of processing circuit(s). Each prefetch access comprises checking whether a respective data is cached in a cache entry and each demand access comprises accessing a respective data. The joint scheduler is adapted to, responsive to each hit prefetch access dispatched for a respective data relating to a respective instruction, associate the respective instruction with a valid indication and a pointer to a respective cache entry storing the respective data such that the demand access relating to the respective instruction uses the associated pointer to access the respective data in the cache, and responsive to each missed prefetch access dispatched for a respective data relating to a respective instruction, initiate a read cycle for loading the respective data from next level memory and cache it in the cache.