Cache-Aware Multi-Processor Bridge for Coherent Memory Throughput
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Solution Overview
Problem
In multi-core systems, the heterogeneity of processor components and memory access characteristics leads to increased CPU stall overhead and reduced memory throughput due to differing cache structures and access latencies, making it challenging to maintain data coherency and maximize shared memory bandwidth.
Innovation Solution
A multi-core processing system with a shared memory controller that manages traffic between processor cores and external memories, using a memory management command to load data into cache memory before instruction execution, and formatting commands for cache controllers to optimize memory access and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interconnect handles memory accesses in a serial fashion to guarantee data coherency, then data consistency is maintained, but memory throughput and bandwidth are reduced
Solution Approach 1:
The system performs preliminary actions by identifying and allocating critical memory lines to CPU caches before they are actually needed for execution. The memory management command pre-loads critical data into the CPU cache, ensuring that when the CPU needs this data, it is already available, thus reducing stall overhead without requiring serial interconnect handling.
Solution Approach 2:
The memory management command is segmented into different types: critical line requests that require immediate CPU cache allocation and non-critical line requests that can be handled differently. This segmentation allows the system to prioritize CPU-critical data while maintaining overall memory throughput, resolving the contradiction between coherency and productivity.
2Loss of time
If cache components issue cache allocate accesses to return critical line first, then CPU stall overhead is reduced, but other CPU's stall overhead increases and shared memory throughput decreases
Solution Approach 1:
The memory management command performs preliminary allocation of critical memory lines to specific CPU caches before the CPUs need the data. This advance preparation reduces CPU stall overhead by ensuring critical data is already cached, while the non-critical lines can be allocated later without impacting CPU performance, thus maintaining shared memory throughput.
Solution Approach 2:
The system applies different quality levels of service to different memory lines based on their criticality. Critical lines receive immediate attention and are allocated to specific CPU caches with high priority, while non-critical lines receive standard service. This local differentiation reduces overall CPU stall overhead without significantly impacting shared memory throughput.
3Adaptability or versatility
If heterogeneous components with different cache structures access shared resources, then system functionality is enhanced, but access latency and complexity increase
Solution Approach 1:
The memory management command provides a universal interface that works across heterogeneous components with different cache structures. By using a standardized command format that can specify criticality and target CPU, the system achieves multi-functionality without increasing access latency or complexity for individual components.
Data Source
AI summary
Techniques for loading data, comprising receiving a memory management command to perform a memory management operation to load data into the cache memory before execution of an instruction that requests the data, formatting the memory management command into one or more instruction for a cache controller associated with the cache memory, and outputting an instruction to the cache controller to load the data into the cache memory based on the memory management command.