Does UBI still place a just-tortured block first in the free block list?

[Atlant Schmidt]

Artem:

  Thanks!

  We'll consider these suggestions and see if we can
  devise a generally-useful patch!

                                 Atlant

-----Original Message-----
From: Artem Bityutskiy [mailto:dedekind1 at gmail.com]
Sent: Tuesday, July 01, 2014 11:15 AM
To: Atlant Schmidt
Cc: 'linux-mtd at lists.infradead.org'; Cale Surgen
Subject: Re: Does UBI still place a just-tortured block first in the free block list?

On Tue, 2014-07-01 at 11:02 -0400, Atlant Schmidt wrote:
>   I guess I'll go find that tree and see how we might
>   change things so that a different block would win
>   the next election. Any suggestions?

What you say sounds like the problem is not in the PEB selection
algorithm. The problem is in the "bad/good" criteria that we use.

What you say is that currently UBI is unable to reliably tell whether a
PEB is good or bad. And instead of just marking a PEB as bad, we keep
try to re-use it.

If I got it right, then I'd suggest 2 solutions.

1. Improve the 'torture' function and make it work for your case. It
would not solve the problem in general, but would solve your problem.

2. Try to detect situations when a PEB is tortured "too often". I am not
sure how to do this reliably, though, but may be you can invent
something. I guess the right way is to introduce a counter and store it
in the EC header. We have plenty of unused space there.

--
Best Regards,
Artem Bityutskiy


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