Re: [ECOS] FW: Mount JFFS2 root file system issue

[Jürgen Lambrecht <J dot Lambrecht at televic dot com>]

Hello Bin,

I am also struggling with JFFS2, and I did already a lot of tests.
There more files you have in jffs2, the longer it takes to mount:
- per inode, 16 B (static) or 24 B (dynamic) are written in RAM
- per file, more or less 72 B (found by testing, I should check the 
jffs2 sources..) are written in RAM
Also, during mounting, a garbage collect is done. As explained below, 
the file system (the journal) is then checked. And the bigger the flash, 
the more time it can take.

Indeed, once the boot time is long, you can only solve it by formatting 
jffs2.

I can reproduce this this way: I put 1000 files in 1 directory, then I 
delete 997 of them, and still mounting and also opening of 1 file takes 
very long. To go more in detail: mounting goes from 11s to 10s, but 
opening 1 file goes from 570ms to 820ms.

Regards,

Jürgen Lambrecht
R&D Engineer
Televic Transport Systems
http://www.televic.com
Televic NV / SA (main office)  	
Leo Bekaertlaan 1
B-8870 Izegem
Tel: +32 (0)51 303045
Fax: +32 (0)51 310670



Gary Thomas wrote:

> Lin, Bin (Bin) wrote:
>
> > Hi Gary,
> >
> > Thanks a lot for your reply.
> > It is understandable that JFFS2 needs to rebuild/recover the active
> > nodes in the next reboot after failure.  But once this happen, every
> > reboot later on will take the same amount of time which is much long
> > than normal. I have to re-program the entire flash to get it back to
> > normal mount time.
> > Also this problem can not reproduced in the lab. Is there a way to
> > craete this problem quickly?
>
>
> No clue, sorry.
>
> As I said, since this isn't an eCos issue, you should ask the JFFS2
> folks (linux-mtd@lists.infradead.org) or Linux mailing lists.
>
> > -----Original Message-----
> > From: Gary Thomas [mailto:gary@mlbassoc.com] Sent: Friday, January 
> > 11, 2008 7:40 AM
> > To: Lin, Bin (Bin)
> > Cc: ecos-discuss@sourceware.org
> > Subject: Re: [ECOS] FW: Mount JFFS2 root file system issue
> >
> > Lin, Bin (Bin) wrote:
> >
> > > Hello All,
> > >
> > > I have ARM9 systems with JFFS2 root file system. For some reasons, e.g.
> >
> > > system crash or power failure, when system boots up next time, it 
> > > takes much longer time than usual to mount jffs2 root file system. 
> > > It can hang at following message for 3-10 min. The system will 
> > > eventually
> >
> >
> > > come up and function well. This problem occurred on less than 10% of 
> > > boards.
> >
> >
> > I think this can happen (after such a failure) when JFFS2 realizes that
> > it needs to rebuild/recover the active nodes in the file system.  This
> > can require a scan of the entire file system, along with rewriting some
> > nodes, etc.
> >
> > > NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
> > > Fast Floating Point Emulator V0.9 (c) Peter Teichmann.
> > >
> > > There are some symbolic links in the root file system. These links 
> > > is linked to the files in another partition. Could that cause 
> > > problem if the file in the other partition gets corrupted? This 
> > > behaviour is not reproducible. Looks like the files in the flash are 
> > > not corrupted. I guess the corruption could be in jffs2 file system.
> > >
> > > Anyone has seen this issue, and solution?
> > >
> > > Appreciate very much for any input,
> >
> >
> > This looks to be a Linux kernel issue - I don't see what it has to do
> > with eCos.
> >
> > You should probably ask on some appropriate Linux mailing list.

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