Hi Baidu,
Hi,Detlev :
2011/4/19 Detlev Zundel dzu@denx.de:
Hi Baidu,
Syncs up with jffs2 in the linux kernel: 1/ Change DEFAULT_EMPTY_SCAN_SIZE from 4KB to 256 Bytes. 2/ If the 1KB data is 0xFF after the cleanmarker, skip and scan the next sector. 3/ Change the buffer size from 4KB to 128KB which is the common size of erase block.
There is no "common size of erase block". Looking into the Linux code, it uses "max(erase block size, 128k)" for its buffer to speed up reading from NAND and the 128k seem to be a kmalloc limit.
So maybe a "increase buffer size from 4KiB to 128KiB to reduce number of read operations" would be more fitting. By the way, does this change contribute to the performance increase at all, or is the increase simply due to DEFAULT_EMPTY_SCAN_SIZE?
Yes, I think it is useful to speed up the scanning.
Don't get me wrong, but I was not asking whether you "think" it speeds up the scanning. When it comes to performance, I learnt to trust numbers olnly. This may in part be because I myself occassionally was completely wrong in predicting performance issues.
So I am still eager to see actual numbers if this _really_ speeds up scanning.
Cheers Detlev