[RFC] slight UBI scan time improvement

[Artem Bityutskiy]

Hi,

On Wed, 2008-04-23 at 10:13 +0200, Matthieu CASTET wrote:
> > [    0.950000] NAND device: Manufacturer ID: 0xec, Chip ID: 0xdc (Samsung NAND 512MiB 3,3V 8-bit)
> > [    0.960000] Scanning device for bad blocks
> > [    1.000000] Bad eraseblock 494 at 0x03dc0000
> > [    1.050000] Bad eraseblock 1300 at 0x0a280000
> > [    1.140000] Bad eraseblock 2554 at 0x13f40000
> > [    1.160000] Bad eraseblock 2923 at 0x16d60000
> > [    1.200000] Bad eraseblock 3349 at 0x1a2a0000
> > [    1.230000] Bad eraseblock 3790 at 0x1d9c0000
> > [    6.890000] UBI: attached mtd9 to ubi0
> > 
> > 
> > 
> > Hamish
> 
> Do you know when the bad block scanning finish and the ubi scan start ?

Good point Matthieu. Indeed, _at least_ 1.23 sec is spend in the driver
for scanning against bad eraseblocks to build in-memory bad block table
(BBT). And it is probably more than 1.23 sec. If you start using
on-flash bad block table, this should go away. I never used on-flash
BBT, but I know MTD supports this and for example OLPC has on-flash BBT.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)