TLB Invalidation Buffering to Prevent MMU Translation Stalls
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems face challenges in efficiently managing address translation requests and invalidation requests in a multi-core processing system, leading to potential stalls and blocking of processor core operations due to full transaction buffers.
Innovation Solution
The proposed solution involves a Memory Management Unit (MMU) with a Translation Lookaside Buffer (TLB) that includes matching logic to generate address transactions and invalidation match transactions. These transactions are routed through either a general-purpose transaction buffer or a dedicated invalidation buffer, ensuring non-stalling and non-blocking operations even when the general-purpose buffer is full.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single general-purpose transaction buffer is used for both address translation requests and invalidation requests, then device complexity is reduced, but processor core operations may stall when the buffer is full
Solution Approach 1:
The single general-purpose transaction buffer is segmented into two dedicated buffers: a first transaction buffer for address translation requests and a second transaction buffer for invalidation requests. This segmentation allows independent management of different request types, preventing stalls in processor core operations while maintaining reasonable device complexity.
2Productivity
If address translation requests are prioritized over invalidation requests, then address translation performance is improved, but invalidation operations may be delayed
Solution Approach 1:
By segmenting the buffer into dedicated buffers for address translation and invalidation requests, both request types can be processed simultaneously without prioritization delays. The segmentation eliminates the time loss for invalidation operations while maintaining high address translation throughput.
3Productivity
If the transaction buffer capacity is increased to prevent stalls, then processor core operation continuity is improved, but device complexity and resource usage increase
Solution Approach 1:
Instead of increasing the capacity of a single general-purpose buffer, the system segments the buffer into two smaller dedicated buffers. This segmentation maintains operation continuity by preventing stalls for each request type while keeping the total device complexity and resource usage manageable.
4Ease of operation
If a dedicated invalidation buffer is implemented, then invalidation request processing is improved, but device complexity increases
Solution Approach 1:
The dedicated invalidation buffer is implemented as a segmented portion of the overall buffer structure, clearly separating invalidation request handling from address translation requests. This segmentation improves ease of operation for invalidation requests while maintaining organized and manageable device complexity through structured buffer architecture.
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.