CPU Interconnect Bus Tracing via Peripheral Switch Memory
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Solution Overview
Problem
The scalability and aggregate performance of multiprocessor systems are limited due to complex interprocessor communication issues, which are difficult to debug and optimize, especially under saturation conditions, leading to potential performance losses.
Innovation Solution
Utilizing an external peripheral interconnect switch with multiple ports to examine interprocessor communication traces at a switch memory, allowing simultaneous saturation of CPU interconnect buses and thorough analysis of communication behavior under maximum data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If CPU interconnect buses are used for interprocessor communication in multiprocessor systems, then throughput bandwidth and latency are improved, but workload scalability and aggregate performance increase slower than the number of processors
Solution Approach 1:
The patent introduces an external peripheral interconnect switch as an intermediary device to capture, store, and analyze communication traces between processors. This mediator allows observation of interprocessor communication without interfering with the actual data flow, enabling identification of scalability bottlenecks while maintaining high-speed communication through the original CPU interconnect buses.
2Difficulty of detecting and measuring
If external monitoring of interprocessor communication is implemented, then debugging capability is improved, but system complexity and measurement difficulty increase
Solution Approach 1:
The patent creates a copy of the communication traces by capturing data through the peripheral interconnect switch's memory buffer. Instead of directly monitoring or intercepting actual communication streams, the system creates duplicate trace data that can be analyzed independently, simplifying the measurement process while maintaining system integrity.
Solution Approach 2:
The peripheral switch acts as an intermediary that naturally captures communication traces without requiring complex monitoring infrastructure. By leveraging the existing switch memory and DMA capabilities, the system obtains communication data through standard peripheral interfaces rather than requiring specialized measurement equipment.
3Productivity
If CPU interconnect buses operate under saturation conditions, then maximum throughput is achieved, but performance issues and errors become more difficult to detect
Solution Approach 1:
The patent performs preliminary capture of communication traces before performance degradation occurs. By continuously buffering communication data in the peripheral switch memory during saturation conditions, the system preserves evidence of communication patterns and errors that would otherwise be lost or difficult to reproduce during high-stress operation.
Solution Approach 2:
The system establishes feedback by analyzing captured traces to identify performance issues and using this information to optimize interprocessor communication. The trace analysis provides feedback about communication patterns, bottlenecks, and errors that inform subsequent system configuration and performance tuning decisions.
Data Source
AI summary
A DMA controller of a peripheral switch is programmed to transfer memory contents to a switch memory including an instruction for a second processor. The instruction is sent from a second port of the switch coupled to a second peripheral lane of the second processor. Then, the contents are transferred to the switch memory using a first port of the switch coupled to a first peripheral lane of the first processor. The memory contents include first data transferred by the second processor to the first processor using a central processing unit (CPU) bus connection in response to the instruction.