Context-Aware Memory Bandwidth Limiting for Multiprocessing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multiprocessing systems face memory bottlenecks and contention for memory bandwidth, which can lead to performance issues, especially in safety-critical applications, due to unmanaged access by multiple subsystems and virtual machines in complex automotive systems.
Innovation Solution
A multiprocessing apparatus with a bandwidth monitoring subsystem that limits memory access based on context, ensuring each subsystem operates within defined memory bandwidth portions, and a resource management subsystem that enforces these limitations, allowing for prioritization of safety-critical contexts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple subsystems access memory simultaneously without bandwidth management, then memory bandwidth utilization increases, but memory bottlenecks and contention occur leading to performance degradation
Solution Approach 1:
The patent segments memory bandwidth into multiple virtual channels, each dedicated to specific subsystems or contexts. This segmentation allows simultaneous access by multiple subsystems while preventing any single subsystem from monopolizing the memory interface, thereby resolving the contradiction between high utilization and stable performance.
Solution Approach 2:
The patent implements dynamic bandwidth allocation where memory access permissions are adjusted in real-time based on the operational context of each subsystem. Safety-critical contexts receive guaranteed bandwidth while non-critical contexts receive remaining capacity, allowing the system to adapt to changing conditions and maintain both high utilization and performance stability.
2Reliability
If memory bandwidth is allocated to safety-critical contexts, then reliability of safety functions improves, but available bandwidth for non-critical functions decreases
Solution Approach 1:
The patent applies local quality by providing different bandwidth guarantees to different contexts based on their criticality. Safety-critical contexts receive guaranteed minimum bandwidth with high priority, while non-critical contexts receive best-effort service using remaining bandwidth. This differentiated approach ensures safety functions have sufficient resources while non-critical functions utilize available capacity.
Solution Approach 2:
The patent introduces a memory management intermediary that sits between subsystems and the memory interface. This intermediary monitors context states, enforces bandwidth limits, and dynamically adjusts allocation to ensure safety-critical functions receive guaranteed bandwidth while allowing non-critical functions to utilize remaining capacity, thus resolving the resource allocation contradiction.
3Reliability
If memory access is limited by context to prevent bottlenecks, then memory contention is reduced, but system complexity increases due to bandwidth management overhead
Solution Approach 1:
The patent implements a universal memory interface controller that handles multiple functions: bandwidth monitoring, context management, virtual channel arbitration, and credit-based flow control. By consolidating these functions into a single multi-functional controller rather than separate mechanisms, the patent reduces overall system complexity while maintaining stable memory access.
Solution Approach 2:
The patent enables subsystems to self-manage their memory access by providing them with context identifiers and bandwidth parameters. The memory management controller automatically monitors and enforces bandwidth limits based on these parameters without requiring complex external control logic, thereby reducing system complexity while ensuring stable access patterns.
Data Source
AI summary
A multiprocessing apparatus includes memory configured to support a maximum data access rate expressed as memory bandwidth, a plurality of subsystems coupled to the memory, each of the plurality of subsystems being configured to switch between two or more contexts, a bandwidth monitoring subsystem configured to limit access to the memory by a first subsystem to a first portion of the memory bandwidth when the first subsystem is configured for a first context, and to limit access to the memory by the first subsystem to a second portion of the memory bandwidth when the first subsystem is configured for a second context, and a resource management subsystem configured to enforce memory bandwidth limitations defined by the bandwidth monitoring subsystem based on context in which the first subsystem is operated.