MMU TLB Miss Handling via Queue Buffer Segmentation
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Solution Overview
Problem
Memory management units (MMUs) with multi-channel bus interfaces face issues due to channel misses during virtual address to physical address translation, leading to increased miss penalty and processing time.
Innovation Solution
A memory management unit (MMU) with a page table, first and second translation lookaside buffer (TLB) lookup logic, and queue buffers to handle virtual address translations, where TLB misses are processed efficiently by storing missed virtual addresses in a queue and accessing the page table to determine corresponding physical addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the MMU uses a multi-channel bus interface for memory access, then memory bandwidth and throughput are improved, but channel misses cause other channels to wait, increasing processing time
Solution Approach 1:
The MMU is divided into multiple independent translation channels (first channel, second channel, etc.), each capable of independently translating virtual addresses to physical addresses. This segmentation allows parallel processing of address translations across different channels, preventing a miss in one channel from blocking others and reducing overall processing time while maintaining high memory bandwidth.
2Reliability
If the MMU translates virtual addresses to physical addresses using traditional methods, then address translation is achieved, but TLB misses require waiting for page table access, increasing miss penalty
Solution Approach 1:
The Translation Lookaside Buffer (TLB) pre-stores frequently used virtual-to-physical address mappings before they are needed. When a translation is required, the system first checks the TLB for a cached mapping. If found (TLB hit), the translation is immediately provided without waiting for page table access. This preliminary caching action significantly reduces the miss penalty while maintaining accurate address translation.
3Reliability
If the MMU waits for TLB misses to be processed before handling other translations, then translation accuracy is maintained, but other channels must wait, reducing overall efficiency
Solution Approach 1:
The MMU employs multiple independent translation channels that can operate simultaneously. Each channel has its own TLB and translation logic, allowing one channel to handle a TLB miss without blocking other channels from performing their own translations. This segmentation maintains translation accuracy in each channel while preserving overall translation throughput across the multi-channel system.
Data Source
AI summary
The memory management unit includes a page table correlating respective virtual addresses with corresponding physical addresses, first translation lookaside buffer (TLB) lookup logic that provides one of a first virtual address and a first physical address according to whether a page number of the first virtual address matches a frame number of the first physical address, a first queue buffer that stores and provides the first virtual address, and second TLB lookup logic that determines and provides a first page physical address using the first virtual address to access the page table when the page number of the first virtual address does not match the frame number of the first physical address.