Region Prefetcher Circuit for Non-Patterned Memory Access Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Caches are ineffective in addressing memory access latency issues when memory accesses do not conform to a fixed pattern, and cache misses exacerbate delays in processor-based devices like GPUs due to high memory access latency.
Innovation Solution
Implementing a region prefetcher circuit that uses access bitmaps to detect memory access requests and prefetch memory blocks from system memory or cache into a prefetch buffer based on unset bits, reducing latency by anticipating data needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cache memory is used to reduce memory access latency, then access speed to frequently accessed data is improved, but memory access latency increases for data with non-fixed access patterns due to cache misses
Solution Approach 1:
The region prefetcher circuit proactively loads data into the prefetch buffer before the processor actually requests it, based on predicted access patterns. This preliminary action ensures that data is already available in the buffer when needed, eliminating cache miss delays and reducing memory access latency for non-patterned accesses
2Loss of time
If cache memory is used to store frequently accessed data, then memory access latency is reduced for cached data, but the complexity of the memory hierarchy increases
Solution Approach 1:
The prefetch buffer serves as an intermediary structure between the cache and system memory, specifically designed to handle prefetching operations. This separate buffer simplifies the overall memory hierarchy by dedicating a specific component to the prefetching function, rather than complicating the cache structure itself
3Reliability
If the processor waits for memory access requests to be fulfilled, then data accuracy is ensured, but instruction execution is stalled and productivity decreases
Solution Approach 1:
The region prefetcher circuit proactively loads data into the prefetch buffer before the processor actually requests it, based on predicted access patterns. This preliminary action ensures that data is already available in the buffer when needed, eliminating cache miss delays and reducing memory access latency for non-patterned accesses
Solution Approach 2:
The system monitors actual memory access patterns and uses this feedback to refine prefetching predictions. By continuously learning from access behavior, the system maintains data accuracy while optimizing prefetch timing to prevent processor stalling, thus improving instruction execution throughput
Data Source
AI summary
Providing memory region prefetching in processor-based devices is disclosed. In some aspects, a processor-based device comprises a region prefetcher circuit that comprises a plurality of access bitmaps corresponding to a plurality of contiguous memory regions of a system memory device. Each access bitmap comprises a plurality of bits corresponding to a plurality of memory blocks of a contiguous memory region. The region prefetcher circuit detects a memory access request to a memory block of a contiguous memory region, identifies an access bitmap corresponding to the contiguous memory region, and identifies a bit corresponding to the memory block. The region prefetcher circuit sets the bit to indicate the memory access request to the memory block. The region prefetcher circuit subsequently detects a prefetch trigger event, and, in response, identifies one or more unset bits of the access bitmap, and prefetches one or more memory blocks corresponding to the unset bits.