[Yaffs-archive] Re: Performance

[Luc Van Oostenryck]

Christian Gan wrote:
 > By the way, what kind of performance is everybody getting from YAFFS/NAND
 > MTD on Linux?
 >
 > I found that the NAND MTD was really slow and doing things that wasted time
 > (ie. resets for every command, using for loops for ram copies to the data
 > buf, etc).  So I had to rewrite portions that appeared the slowest on the
 > logic analyzer.
 >
 > So I'm curious to see what performance others are getting (can you also
 > include your proc and bus speeds?).
 >
 > Thanks!
 >
 > Christian Gan
 >
 >

Christian,

Here is an extract of one of my previous mail:
  >
  > For the moment what annoy me is the MTD layer that doesn't offer a good
  > interface for NAND and page access. Next week, I will probably write a
  > small MTD-like block device that fit better to NAND access (only page
  > access with HW ECC).
  > In a second time, I will investigate the possiblity to use
  > generic_file_read() and maybe generic_file_write() so we can profit from
  > the disk cache.
  >
  > Best regards
  >
  > Luc Van Oosternyck
  >

IOW I have exactly the problems concerning the NAND MTD.

For performance result (hey show yours, I will show mine :-)
      Read:	185Kb/s
      Write:      85Kb/s
      Write:      175Kb/s		when removing the yaffs code that read back
				each chunk to verify if the write is OK.
      Board is a prototype ARM720 running at 24MHz with a 16bit 12MHz bus, with the SW ECC.
      Definitive version will be faster and will also use HW ECC.

Cheers






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