[RFC] slight UBI scan time improvement

[Hamish Moffatt]

On Wed, Apr 23, 2008 at 03:57:47PM +0300, Artem Bityutskiy wrote:
> 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.

I'm not sure what this means.. ? Instead of having to scan each block
to check the marker, it has a central table? And that table is created
once by an initial scan and then added to when UBI declares a block bad?
How do I access this feature?

> > 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:

Hmm I have busybox (1.9.x) also, 128K works ok for me.

> # 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

Very good. It's about 6.1 seconds for me :-(

(Worse on my previous hardware which had compact flash on IDE without a
hardware IDE controller: over 11 seconds.)


Hamish
-- 
Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>