MDK MIDDLEWARE: File System Slows Down With Large Number of Files

Information in this knowledgebase article applies to:

• Keil MDK Middleware File System

SYMPTOM

Why does the file system slow down considerably, when I try to create a large number of files on a NOR flash device?

CAUSE

For NOR flash, we use our proprietary EFS (Embedded File System) to provide minimum overhead and maximum space for user data. To accomplish this, EFS does not include the type of indexing that you'll find in more general-purpose file systems, such as FAT32.

Therefore, to create a new file, the EFS driver must search for empty space on the device, by reading sectors until it finds an unused one. As a result, the time to create a new file increases with the number of files already residing on the device.

RESOLUTION

This effect is a limitation of EFS, and will effect any system that creates a large number of files on the device. You can work around it by consolidating data into fewer, larger files, or by switching to another device, such as an SD/MMC card or a NAND flash part, both of which use the FAT file system.

STATUS

Known Limitation

Last Reviewed: Friday, February 12, 2021