File Migration to Persistent Memory via Direct Mapping
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Solution Overview
Problem
Traditional memory-based technologies for file access in file systems require modifications to applications for synchronization with non-volatile memory and often involve page caching, which can be cumbersome and inefficient.
Innovation Solution
The migration of files from a non-persistent memory file system to a persistent memory file system allows direct memory mapping without page caching, using a file migration policy that considers memory mapping history, access frequency, and available storage space, enabling transparent access and reducing the need for synchronization and page caching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If files are accessed using traditional memory mapping with non-volatile memory, then file access speed is improved, but application complexity increases due to required synchronization and flushing operations
Solution Approach 1:
The patent introduces a file system layer as an intermediary between the application and the persistent memory device. This file system handles synchronization and flushing operations automatically, shielding the application from these complex tasks while still enabling fast direct memory mapping access to files stored on persistent memory.
Solution Approach 2:
The system implements automatic migration of files to persistent memory based on access patterns, without requiring application intervention. The file system monitors file access behavior and autonomously decides which files to migrate, reducing the burden on applications while maintaining performance benefits.
2Productivity
If files are migrated to persistent memory file system, then page caching is eliminated and direct memory mapping is enabled, but file migration overhead and storage management complexity increase
Solution Approach 1:
The patent implements dynamic file migration policies that automatically adjust which files reside on persistent memory based on real-time access patterns. Files are migrated to or from persistent memory as needed, allowing the system to optimize I/O performance dynamically without manual intervention while managing storage resources efficiently.
Solution Approach 2:
The system changes the storage location parameter of files dynamically based on access frequency and pattern. By monitoring file access parameters and automatically migrating files between different storage locations (persistent memory vs. traditional storage), the system improves I/O performance without requiring complex manual storage management.
3Speed
If direct memory mapping is used without page caching, then memory access efficiency is improved, but data persistence and reliability requirements become more stringent
Solution Approach 1:
The patent implements preliminary synchronization mechanisms that ensure data is properly flushed to persistent memory before the system needs to guarantee its persistence. By proactively handling synchronization and flush operations through the file system layer, the system maintains data reliability while still enabling fast direct memory mapping access for active file operations.
Data Source
AI summary
Various examples described herein provide for migrating a file between a non-persistent memory file system and a persistent memory file system. In particular, some examples detect, on a non-persistent memory file system, a file that has been memory-mapped while being accessed from the non-persistent memory file system by a computer system, and the detected file is migrated from the non-persistent memory file system to the persistent memory file system.