Linked-List Prefetch Buffer for Memory Latency Reduction
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Solution Overview
Problem
In modern digital systems, particularly in System On a Chip (SOC) designs, memory system latency leads to inefficiencies due to increased access time requirements and inefficient prefetch buffer use, especially in video and multimedia applications with high data demands.
Innovation Solution
A prefetch memory processing system that uses a linked list to manage a prefetch buffer, predicting data needs and storing it in a buffer for quick access, with a prefetch memory interface that checks read/write commands to optimize data retrieval and storage, allowing for efficient use of buffer space and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a linearly addressed stream buffer is used for prefetching, then the buffer structure is simple to implement, but the buffer use efficiency deteriorates and system performance does not improve
Solution Approach 1:
The patent changes the addressing parameter from linear addressing to linked-list-based indirect addressing. This allows the buffer to dynamically adapt to actual data access patterns rather than assuming sequential access, thereby improving buffer hit rates and overall efficiency while maintaining implementation feasibility through the use of standard pointer-based data structures
Solution Approach 2:
The patent introduces dynamic behavior to the buffer management by using a linked list structure that can be reorganized based on data usage patterns. The buffer entries can be inserted, removed, and repositioned dynamically based on prefetch accuracy and actual access needs, allowing the system to adapt to varying workload characteristics rather than being stuck with a static linear structure
2Loss of time
If more data is prefetched to reduce latency, then memory access speed improves, but buffer space utilization deteriorates
Solution Approach 1:
The patent implements partial prefetching by using the linked list to selectively prefetch only the most likely needed data items. Rather than aggressively filling the buffer with excessive data that may never be used, the system performs targeted prefetching based on linked-list pointers that indicate probable access patterns, achieving good latency reduction while maintaining high buffer utilization
Solution Approach 2:
The patent implements a mechanism where buffer entries are dynamically added and removed based on their usefulness. When prefetched data is not needed (determined through linked-list tracking), those buffer slots are freed for other uses. This continuous cycle of adding useful data and discarding unnecessary data maintains optimal buffer utilization while still reducing latency for actually needed data
Data Source
AI summary
A processing device includes a memory and a processor that generates a plurality of read commands for reading read data from the memory and a plurality of write commands for writing write data to the memory. A prefetch memory interface prefetches prefetch data to a prefetch buffer, retrieves the read data from the prefetch buffer when the read data is included in the prefetch buffer, and retrieves the read data from the memory when the read data is not included in the prefetch buffer, wherein the prefetch buffer is managed via a linked list.