JFFS2 errors on ppc-4xx with CFI NOR flash

[Ryan Thompson]

On Fri, Mar 5, 2010 at 3:56 AM, massimo cirillo <maxcir at gmail.com> wrote:
> I suppose you don't have CONFIG_MTD_XIP enabled.
> So in order to completely disable the suspend,
> please in chip_ready() function just after "case FL_ERASING:"
> (line 775) put the line "goto sleep;" and repeat your test.
> Let me know.

By skipping the FL_ERASING case as you suggested, my test now
completes successfully without any INFO-or-higher kernel messages.

However, it still takes a very long time. The initial files are
written out quickly (subjectively, performance seems similar to raw
mtd speed). However, after 50% or so, performance begins to degrade
dramatically. At 65%, a 256KiB file takes 11 sec to write. At 75%, 20
sec. 90%, 38 sec. 95%, 77 sec. 99%, 121 sec. The entire test took 28.4
minutes to go from 3%-100% on the ~32MiB partition.

Performance seems somewhat consistent with my previous result:

> 2010/3/4 Ryan Thompson <i at ry.ca>:
>> The errors continued until the filesystem actually reported 100% full
>> and my script terminated. The entire 3%-100% operation took about 21
>> minutes for <32MiB, and was definitely much slower towards the end
>> with all the errors.

I've done a flash_eraseall -j followed by a reboot before each run.

I also benchmarked the mtdblock performance without JFFS2 (also
getting input from urandom):

# time dd if=/dev/urandom of=/dev/mtdblock16
dd: writing '/dev/mtdblock16': No space left on device
64257+0 records in
64256+0 records out
Command exited with non-zero status 1
real	5m 30.17s
user	0m 0.08s
sys	1m 2.66s
# perl -le 'printf("bytes written = 0x%08x\n", 64256 * 512);'
bytes written = 0x01f60000
# grep modules /proc/mtd
mtd16: 01f60000 00020000 "modules"

- R