JFFS3 & performance

[Jörn Engel]

On Wed, 12 January 2005 08:41:04 -0800, Jared Hulbert wrote:
> 
> Clarification on NOR technology.  Remember that the ability to run
> code XIP is effectively a requirement for a NOR chip.  This means no
> read errors can leave the chip.  I don't see this changing in the
> foreseeable future.  Any read errors that do occur would probably be
> caused by a failed/incomplete program.

Correct.  That requirement comes mostly from having to program the
memory controller before being able to use DRAM.  After the early
boot, it's just nice to have.

> We probably do want to be able to easily retire, reprogram, and/or
> test those blocks/pages that get read errors.  That would have to be
> done in the filesystem and the chip driver needs to be able report a
> read error occured.
> 
> Any chance of being able store special files XIP in JFFS3? 
> Uncompressed aligned page sized chunks, etc.

Would this actually be an advantage?  Last time I looked, it was
cheaper to use more DRAM.  Most DSL routers I see advertised have a
1:4 or 1:8 ratio of NOR:DRAM, so it looks as if the prices haven't
changed much.

Jörn

-- 
Correctness comes second.
Features come third.
Performance comes last.
Maintainability is needed for all of them.