Re: [RFC] slight UBI scan time improvement

[Artem Bityutskiy <dedekind@infradead.org>]

On Thu, 2008-04-24 at 11:53 +1000, Hamish Moffatt wrote:
> Thanks for the info. It looks like this would not save me very much
> time so I don't think I will bother.

Ok.

> I notice in your patch that you read a whole min_io_size block, even
> though you only need the EC and VID headers (total of 128 bytes each, or
> 576 bytes as a single read according to my calculation):

Err, 64 bytes each even.
 
> Won't reading 2K bytes be slower than 576 in some cases? If you have
> soft ECC then you have to read the whole page anyway, but if you have
> hardware ECC then you have no need to read the whole page into RAM.

Yes, I guess. Current MTD implementation reads whole page in any case,
though.

> 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.

-- 
Best regards,
Artem Bityutskiy (Битюцкий Артём)