Cross-page prefetching using contiguity information
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing prefetching technologies face a low hit ratio due to premature cessation of cross-page prefetching, leading to inefficiencies in memory access, as they fail to accurately determine contiguous physical pages from virtual pages.
Innovation Solution
A cross-page prefetching method that utilizes contiguity information to differentiate between contiguous and noncontiguous physical pages, allowing for accurate prefetching even when virtual pages are mapped to noncontiguous physical pages, by using a prefetching device that receives indication messages with physical addresses and contiguity information to determine and store relevant data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing prefetching devices stop prefetching when determining cross-page prefetching is needed, then invalid cross-page prefetching is prevented, but valid cross-page prefetching is also prevented, causing low prefetching hit ratio
Solution Approach 1:
The patent introduces contiguity information as a new parameter to distinguish between valid and invalid cross-page prefetching scenarios. By adding this parameter to the prefetching decision process, the system can differentiate between cases where prefetching should continue versus cases where it should stop, thereby resolving the contradiction between preventing invalid prefetching and maintaining valid prefetching operations
Solution Approach 2:
The patent implements a feedback mechanism where contiguity information is obtained and used to adjust the prefetching behavior. The system receives feedback about physical page contiguity and uses this information to dynamically control whether cross-page prefetching should proceed, enabling adaptive prefetching that avoids invalid operations while maintaining valid ones
2Adaptability or versatility
If virtual pages are mapped to noncontiguous physical pages, then memory flexibility is improved, but cross-page prefetching accuracy deteriorates
Solution Approach 1:
The patent adds contiguity information as an additional parameter to the memory mapping structure. This parameter enables the system to track whether physical pages are contiguous even when virtual pages are mapped to noncontiguous physical locations, thereby maintaining prefetching accuracy while preserving memory mapping flexibility
Solution Approach 2:
The contiguity information acts as an intermediary that bridges the gap between virtual address space and physical address space. It provides additional context about the physical memory layout that helps the prefetching device make accurate decisions even when direct virtual-to-physical mapping relationships are noncontiguous
Data Source
AI summary
A cross-page prefetching method, apparatus, and system are disclosed, which can improve a prefetching hit ratio of a prefetching device, and further improve efficiency of memory access. The method includes: receiving an indication message, sent by a cache, that a physical address is missing, where the indication message carries a mapped-to first physical address and contiguity information of a first physical page to which the first physical address belongs; acquiring a prefetching address according to the first physical address and a step size that is stored in a prefetching device; and if a page number of a physical page to which the prefetching address belongs is different from a page number of the first physical page, and it is determined, according to the contiguity information of the first physical page, that the first physical page is contiguous, prefetching data at the prefetching address.