hi all,
  By the speed comparison on the site,  I changed some configuration in
yaffs2/yaffs2_guts.h to
#define YAFFS_BYTES_PER_SPARE        64
#define YAFFS_BYTES_PER_CHUNK        2048
#define YAFFS_CHUNK_SIZE_SHIFT         11
#define YAFFS_CHUNKS_PER_BLOCK     64

originally it's
#define YAFFS_BYTES_PER_SPARE        16
#define YAFFS_BYTES_PER_CHUNK        512
#define YAFFS_CHUNK_SIZE_SHIFT         9
#define YAFFS_CHUNKS_PER_BLOCK     32

besides the nand flash i used is 16bits wide-bus and support 2kB page(chunk)
read.

but there is no read and write speedup.
Whether  there are some other changes needed to fit it.
The operating system is linux 2.6

Thanks very much!