Page Table Entry Formatter for Cache Storage Optimization
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Solution Overview
Problem
Virtual memory systems face challenges in increasing hit rates due to constraints imposed by memory architecture, including fixed page size and dictated page table entry formats, which incur high processing costs when trying to reformulate page table entries.
Innovation Solution
A method and apparatus that involve generating and formatting page table entries to be compatible with different cache configurations, allowing for efficient allocation and storage in multiple caches, with a table entry formatter that converts and combines entries to optimize cache line configurations, thereby enhancing hit rates without requiring extensive reformatting of page table entries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If page table entries are reformatted to match different cache configurations, then cache hit rates are improved, but processing costs and complexity increase
Solution Approach 1:
The invention segments the page table entry into distinct fields (virtual address, physical address, frame number, offset) and selectively formats only the necessary portions for different cache configurations. This allows the same PTE structure to be adapted to multiple cache types without complete reformatting, reducing processing overhead while maintaining compatibility.
Solution Approach 2:
The invention implements dynamic formatting of page table entries based on the target cache configuration. The formatter adjusts the encoding and layout of PTE fields according to the specific cache requirements, enabling flexible adaptation to different cache sizes and configurations without requiring separate static formats for each cache type.
2Device complexity
If fixed page size is used in memory architecture, then memory management is simplified, but cache hit rates are reduced due to inability to optimize for varying fragment sizes
Solution Approach 1:
The invention changes the parameter representation in page table entries to include explicit frame number and offset fields that can be dynamically interpreted based on fragment size. This allows the system to maintain fixed page size architecture simplicity while introducing flexibility in how pages are mapped and cached, enabling optimization for varying fragment sizes through parameter reinterpretation rather than architectural changes.
Data Source
AI summary
A device for and method of storing page table entries in a first cache. A first page table entry is received having a fragment field that contains address information for a requested first page and at least a second page logically adjacent to the first page. A second page table entry is generated from the first page table entry to be stored with the first page table entry. The second page table entry provides address information for the second page. The second page table entry has a configuration that is compatible with the first cache.