Slow NAND + JFFS2

Semih Hazar semih.hazar at indefia.com
Wed Apr 25 08:12:33 EDT 2007


Hi,

I'm using a 256 MiB NAND Flash from ST -> Manufacturer ID: 0x20, Chip 
ID: 0xda (ST Micro NAND 256MiB 3,3V 8-bit) with JFFS2. The filesystem is 
mounted as rootfs and the size is around 60 megs.

Filesystem operations seem very slow to me. Such as:

It takes almost 1 and a half minutes to copy a 30 meg file.
Mounting the filesystem takes around 1 minute.

# ls -lh
-rw-r--r--    1 root     root        30.3M Jan  1 00:05 gcc.tgz
# time cp gcc.tgz 1
real    1m 22.37s
user    0m 0.09s
sys     1m 22.22s
#


This seemed really slow to me, but I don't have any other benchmarks. 
Can someone comment on these values ?

The processor is at32ap7000 from Atmel, running at 160 MHz.
I'm running kernel 2.6.20.1 with cpu related patches from Atmel and our 
own nand patches which are almost the replica of at91_nand.c (I can send 
it if you need)

I also changed the read enable and write enable pulse timings according 
to the minimum values stated in NAND flash's datasheet.

If this copy/mount time are really slow as I think, where should I check 
? Is this a JFFS2 related issue or should I try to find some problems in 
our nand driver or ... ?

Best regards,
Semih Hazar





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