[maemo-users] N800 Disk Full? Erratic Behavior SOLVED

From: Eero Tamminen eero.tamminen at nokia.com
Date: Mon Oct 29 18:56:43 EET 2007

ext Frantisek Dufka wrote:
>> Note: due to how JFFS2 filesystem (on the device root filesystem),
>> the fuller the filesystem is, the more RAM it also uses (use 50MB
>> of your root file system and the amount of your free RAM goes down
>> a few MB too).
> Oh, few MBs, really? How does it compare to ext2 usage?

I have no idea.  JFFS2 takes also more memory for files which are open.

 > Maybe another argument to boot from mmc with 770?
> Every megabyte counts here.

I think N800 JFFS2 driver rewrites badly fragmented blocks when they get
full (=4KB as compressed), because otherwise very badly fragmented files
(such as 100MB compressed syslog written one line at the time) could 
actually take tens of MBs of RAM (whereas rewriting blocks just slightly
increases flash wearing and need for GC).  I'm not sure whether this
was fixed in the (early) 770 releases, if not, ext2/3 could indeed be
better.  JFFS2 doesn't really scale that well to larger file systems
than what we currently have.

	- Eero

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