FTL Layer with Switching System

8 Jul

Flash since its birth, then its low power consumption, small size, strong vibration resistance and attracted widespread attention. Now, with the G-capacity flash memory enters era of flash memory will certainly be used in the calculation of higher complexity, the task is more complex systems. In these operating systems, almost without exception, have used the exchange system, in order to sacrifice some performance cost to expand the memory space capacity, increase system throughput and the degree of parallel execution. When the flash is used in these systems, since the flash memory I / O interface and the addressing mode of the conventional disk huge difference, so that the switching system can not directly create the swap area in the flash memory. Engineering Preferred NFTL / FTL layer to shield the flash memory device and disk device incompatibility.

NFTL / FTL layer is a device conversion layer. With this layer, the operating system will be able to flash as a disk block devices to use, and on which to build FAT, NTFS, EXT2, EXT3 and the like disk file system. Even in NFTL / FTL layer with the help of the switching system is to be established on the flash profile. However, NFTL / FTL layer in addition to the conversion process because of losses in the device performance, serious “pseudo-effective chunk” problem can lead to a substantial increase in cost of switching systems to read and write, so it was suggested that the flash private switching systems FASS, solves the above NFTL / FTL two defects. FASS significantly reduce the switching system to read and write on the swap area overhead. However, the continuation of the traditional exchange system FASS statically allocated swap area inertia of thinking, reading and writing will exchange system wear limit fixed in a certain area of the flash memory, it can cause excessive wear localized flash, in essence, does not apply to Flash occasions . Based on the above thinking, the subject that must be dynamically allocated memory switching system swap area of storage space. Therefore, this project will be integrated into the switching system supporting flash file system YAFFS, we propose a switching system supports Flash File System SA-YAFFS (Swap-Aware YAFFS).


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