[RFC] slight UBI scan time improvement

[Hamish Moffatt]

On Thu, Apr 24, 2008 at 09:21:20AM +0300, Artem Bityutskiy wrote:
> On Thu, 2008-04-24 at 11:53 +1000, Hamish Moffatt wrote:
> > Hmm. The software ECC seems to work internally on 256 byte blocks.
> > However it appears that nand_base will always read in a whole page (2K
> > on my flash). It should be ok to read only a 256-byte block as that's
> > all you need for ECC calculation? Not a whole 2K which requires 8 ECC
> > calculations.
> 
> However, there was a patch from Alexey which may certainly help you. It
> was not looked at properly, unfortunately. I'll try to find it in my
> mailbox and will send to you.

Thanks. Yes I found the patch in my linux-mtd folder too. It's very
nice!

Here's my attach time before:

[    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
[    6.900000] UBI: attached mtd9 to ubi0

... and now:

[    0.950000] NAND device: Manufacturer ID: 0xec, Chip ID: 0xdc (Samsung NAND 512MiB 3,3V 8-bit)
[    0.970000] Scanning device for bad blocks
[    1.000000] Bad eraseblock 494 at 0x03dc0000
[    1.060000] Bad eraseblock 1300 at 0x0a280000
[    1.140000] Bad eraseblock 2554 at 0x13f40000
[    1.170000] Bad eraseblock 2923 at 0x16d60000
[    1.200000] Bad eraseblock 3349 at 0x1a2a0000
[    1.230000] Bad eraseblock 3790 at 0x1d9c0000
[    3.880000] UBI: attached mtd9 to ubi0


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