mounting jffs2

Artem B. Bityuckiy dedekind at
Wed Apr 13 09:50:25 EDT 2005

On Wed, 2005-04-13 at 13:25 +0000, Sergei Sharonov wrote: 
> Hi,
> It looks like there is a long delay before filesystem becomes available 
> after mount returns. Test setup: jffs2 on 256 MByte NAND chip, 2.6.10 linux
> with recent mtd snapshot. Filesystem contains one 200 MByte file written 
> and fsynced in 1 kByte chunks.
Believe me, if you'll write in 4K chunks, you'll effect much better
JFFS2 performance. 

> Checking ps it appears that gcd was the only 
> thing running (RWN).
It isn't bug, it is a feature. To facilitate faster mount JFFS2 defers a
lot of work to the GC thread and performs this work just after mount.
You may read filesystem but can't write. Any writer will be blocked - in
your case on 11m10.058s time interval.

> Mount and touch were run immediately one after another. I think it may be
> related to the long umount time problem that I reported before.
Measure the time of unmount just after mount. If if is also around
11m10.058s - this is a bug. Theoretically GC thread must forget its
deferred work and quit immediately.

Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.

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