Program Counter Indexed Address Translation for TLB Miss Hotspots
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The translation from virtual memory addresses to physical memory addresses in computer systems is resource-intensive and slows down program execution due to the high number of misses in the translation lookaside buffer (TLB) for a small number of instructions, and these instructions frequently access the same page table entries.
Innovation Solution
Implementing a program counter (PC) indexed address translation table (PCAT) that stores page table entry information for static instructions, leveraging hierarchical caching and dynamic updates based on TLB misses to optimize translation speed and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a translation lookaside buffer (TLB) is used to cache virtual-to-physical memory address translations, then translation speed is improved for most instructions, but a small number of static instructions still cause disproportionate TLB misses, leading to slow translation when these instructions are executed
Solution Approach 1:
The patent segments the address translation mechanism into two parts: the existing TLB for dynamic instruction translations and a new Program Counter Indexed Data Address Translation Table (PCIDAT) specifically for static instructions. This segmentation allows each component to optimize for its specific purpose, with the PCIDAT ensuring reliable translation for the small number of static instructions that cause TLB misses.
Solution Approach 2:
The PCIDAT acts as an intermediary between the program counter and the TLB for static instructions. When a static instruction is executed, the PCIDAT is first consulted using the program counter as an index to obtain the physical base address, which is then used to access the TLB. This intermediary structure prevents TLB misses for static instructions while maintaining the TLB's efficiency for dynamic instructions.
2Reliability
If page tables are accessed to translate virtual memory addresses to physical memory addresses, then complete address translation is achieved, but substantial memory resources are consumed and program execution speed is reduced
Solution Approach 1:
The PCIDAT performs preliminary action by pre-calculating and storing the physical base address for each static instruction in the PCIDAT using the program counter as an index. This preliminary calculation eliminates the need for subsequent page table walks when these instructions are executed, significantly improving program execution speed while maintaining complete address translation through the combined PCIDAT-TLB mechanism.
3Loss of time
If a program counter indexed address translation table (PCAT) is implemented to cache translations for static instructions, then translation time is reduced and energy is saved, but additional data structures and access logic are required
Solution Approach 1:
The patent applies local quality by creating a specialized, simplified PCIDAT structure with specific local optimizations: using the program counter directly as an index, storing only the physical base address rather than complete page table entries, and implementing a dedicated access path for static instructions. This localized optimization reduces overall translation time without requiring complete restructuring of the address translation system.
Data Source
AI summary
Translation between virtual memory addresses and physical memory addresses is mediated by a program counter indexed table holding virtual and corresponding physical addresses. In some embodiments, this table can be accessed early in the fetch cycle and avoid likely TLB misses.