File System I/O Request Concurrency and Lock Optimization
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Solution Overview
Problem
Conventional file systems process random write I/O requests sequentially, leading to degraded performance, increased response time, and heightened CPU contention due to synchronous processing of write operations, which negatively impacts storage system efficiency and file system integrity.
Innovation Solution
Implementing a method to gather and process multiple write I/O requests concurrently, allowing map-for-write and commit-map-for-write operations to be performed together, thereby reducing the number of times file system locks are acquired and inodes updated, and optimizing RAID disk usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If write I/O requests are processed sequentially, then file system consistency is maintained, but write throughput and performance degrade
Solution Approach 1:
The patent segments the write I/O request processing into distinct phases (map-for-write operations, data transfer, commit-map-for-write operations) that can be executed concurrently for different requests. This segmentation allows the system to process multiple requests in parallel while maintaining the necessary ordering within each phase, thereby improving write throughput without sacrificing consistency.
Solution Approach 2:
The patent implements dynamic processing where the system adapts the execution order of I/O requests based on their phases. Different phases of different requests can be executed in different orders concurrently, with the system dynamically managing the execution flow to optimize performance while ensuring that committed operations are properly ordered. This dynamic approach resolves the contradiction between sequential processing safety and parallel processing speed.
2Reliability
If synchronous processing is used for write operations, then file system integrity is ensured, but CPU contention increases
Solution Approach 1:
By segmenting write operations into distinct phases and allowing concurrent execution of different phases for different requests, the patent reduces the time each CPU core needs to hold locks and maintain state. This segmentation decreases CPU contention while preserving file system integrity through proper phase ordering and commit protocols.
3Productivity
If random write I/O requests are processed sequentially, then resource conflicts are avoided, but storage system efficiency decreases
Solution Approach 1:
The patent implements dynamic request scheduling that allows multiple random write requests to be processed concurrently by adapting the execution order based on request phases and resource availability. This dynamic approach improves storage system efficiency and reduces response time compared to rigid sequential processing, while still avoiding resource conflicts through proper synchronization at phase boundaries.
Data Source
AI summary
A method is used in managing I/O requests in file systems. A first and second I/O requests are received. The first I/O request is directed to a first portion of a file and the second I/O request is directed to a second portion of the file. Respective first portions of the first and second I/O requests are performed concurrently. Respective second portions of the first and second I/O requests are performed concurrently. Execution of the second I/O request starts before execution of the first I/O request finishes.