linux-kernel - Re: UBI fastmap updates

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Date:	Tue, 07 Aug 2012 09:29:46 +0200
From:	Richard Weinberger <richard@....at>
To:	dedekind1@...il.com
CC:	artem.bityutskiy@...ux.intel.com, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org, adrian.hunter@...el.com,
	Heinz.Egger@...utronix.de, thomas.wucher@...utronix.de,
	shmulik.ladkani@...il.com, tglx@...utronix.de,
	tim.bird@...sony.com, Marius.Mazarel@...l.ro,
	nyoushchenko@...sta.com
Subject: Re: UBI fastmap updates

Am 07.08.2012 06:21, schrieb Artem Bityutskiy:
> On Mon, 2012-08-06 at 19:36 +0200, Richard Weinberger wrote:
>> I think we enable fastmap only if a MTD device has more than
>> UBI_FM_MAX_START*2 PEBs.
>> Any comments?
> 
> With double space one can make it power-cut tolerant, because you should
> be able to have either old or new fastmap at any point of time.

UBI_FM_MAX_START*2 has nothing do to with the Fastmap size.
IMHO we need a threshold where Fastmap makes sense.
Technically Fastmap can only be used if a MTD device has >= UBI_FM_MAX_START
PEBs.
But does this makes sense? Fastmap was invented to speedup attaching on *large* MTDs,
The benefit in small MTDs is very little.

Thanks,
//richard


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