exFAT With Linux 6.2 Allows Creating Files & Directories Much Faster
Linux's exFAT file-system support has matured rather nicely over the past 3+ years. Ever since the 2019 milestone of Microsoft publishing the exFAT specifications and encouraging Linux use, this file-system driver -- which merged in early 2020 with Linux 5.7 -- has been on a stellar trajectory. The exFAT improvements come thanks in large part to the likes of Samsung, Sony, and other vendors relying on this kernel driver for supporting this SD card and USB flash drive focused file-system in their consumer devices.
An interesting change by Sony for exFAT in Linux 6.2 is around hinting of empty directory entries. In turn the few dozen lines of code changed helps avoid repeated traversals of directory entries. This improvement helps reduce CPU usage and allows for better performance when creating files and directories particularly on lower-end processors.
When testing the exFAT change on a class-4 SD card using an i.MX6Q SoC, Sony engineer Yuezhang Mo found that with few files there were around a 14% improvement in the speed at which the files were created. Or if creating thousands of files the exFAT performance can be as much as 50%.
This significant performance optimization for file and directory creation is part of the exFAT updates sent in for the Linux 6.2 merge window along with other optimizations and code improvements.