TLB Invalidation Buffering for Non-Blocking Address Translation
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Solution Overview
Problem
Existing memory management systems face challenges in efficiently handling address translation and invalidation requests, leading to processing bottlenecks and resource inefficiencies.
Innovation Solution
A Memory Management Unit (MMU) with a Translation Lookaside Buffer (TLB) is designed to receive address translation and invalidation requests, utilizing matching logic to generate transactions that indicate hit, partial hit, or miss conditions, and routing these transactions through general-purpose and dedicated buffers to prevent stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a TLB is used to cache address translations, then address translation performance is improved, but processing bottlenecks occur during invalidation operations
Solution Approach 1:
The patent segments the transaction buffer into multiple independent buffers (first buffer for address translation requests, second buffer for address invalidation requests). This segmentation allows invalidation requests to be processed independently without blocking translation requests, resolving the bottleneck where invalidation operations stalled the entire TLB processing pipeline.
Solution Approach 2:
The patent introduces match outcome signals as intermediaries that decouple the validation process from the main processing pipeline. The matching logic generates match outcome signals that indicate whether invalidation requests match existing translations, allowing the system to proceed with invalidation without waiting for the complete translation process to finish, thus eliminating stalls.
2Device complexity
If address invalidation requests are processed through the same buffer as address translation requests, then device complexity is reduced, but processing stalls occur
Solution Approach 1:
The patent divides the single transaction buffer into two separate buffers: one dedicated to address translation requests and another to address invalidation requests. This segmentation prevents invalidation operations from blocking translation operations, maintaining high processing throughput while keeping each individual buffer relatively simple in structure.
Solution Approach 2:
The patent implements dynamic buffer management where the system can selectively process translation requests and invalidation requests based on buffer status and request priority. This dynamic approach allows the system to maintain simplicity in individual buffer designs while achieving high overall throughput through flexible, context-dependent processing.
Data Source
AI summary
A method includes receiving, by a MMU for a processor core, an address translation request from the processor core and providing the address translation request to a TLB of the MMU; generating, by matching logic of the TLB, an address transaction that indicates whether a virtual address specified by the address translation request hits the TLB; providing the address transaction to a general purpose transaction buffer; and receiving, by the MMU, an address invalidation request from the processor core and providing the address invalidation request to the TLB. The method also includes, responsive to a virtual address specified by the address invalidation request hitting the TLB, generating, by the matching logic, an invalidation match transaction and providing the invalidation match transaction to one of the general purpose transaction buffer or a dedicated invalidation buffer.