[RFC] slight UBI scan time improvement

[Artem Bityutskiy]

On Wed, 2008-04-23 at 22:40 +1000, Hamish Moffatt wrote:
> Well I think from past use of "time ubiattach ..." that most of
> the missing time is in the attach. 
Sure, UBI takes most of the time. Its just if you want to save 1.2+ sec,
you may try to play with on-flash BBT.

> Would combining the bad block scan with the UBI scan save time? I guess
> it would be a bad layering violation however :-)
Yeah, it could be done as custom hack but not for mainstream.

> What sort of speed do you get using
> dd if=/dev/mtdblock9 of=/tmp/foo bs=128K count=64
> (where mtdblock9 is your raw mtd NAND device). I'm seeing about 6
> seconds to read that 8Mb, which is quite long I guess.

I have busybox so stuff like 128K does not work. Here are my results:

# time dd if=/dev/mtd4 of=/dev/null bs=131072 count=64
64+0 records in
64+0 records out
real    0m 0.28s
user    0m 0.00s
sys     0m 0.28s

# time dd if=/dev/mtd4 of=/dev/null bs=131072 count=256
256+0 records in
256+0 records out
real    0m 1.12s
user    0m 0.00s
sys     0m 1.11s

Its OneNAND which has a controller and it is quite quick.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)