jffs2 on Ecos: multi task access and defragmentation

jffs2 on Ecos: multi task access and defragmentation

[Armelle Potier]

2 questions:
1 - How must be used jffs2 with many task calling it for read-write-erase
operations on different or same files or directory
Is it managed correctly by jffs2 and how (tasks blocked if necessary for
example) or have the task to care for multi access and then how?
2 - does jffs2 need defragmentation functionnality ? If yes how to use this
service if it's exist.

Thanks for your response.
Armelle POTIER

Re: jffs2 on Ecos: multi task access and defragmentation

[David Woodhouse]

On Thu, 2003-10-23 at 10:52 +0100, Armelle Potier wrote:
> 2 questions:
> 1 - How must be used jffs2 with many task calling it for read-write-erase
> operations on different or same files or directory
> Is it managed correctly by jffs2 and how (tasks blocked if necessary for
> example) or have the task to care for multi access and then how?

JFFS2 does locking internally, using semaphore and spinlock primitives
under Linux.

In the eCos build, I believe those locking primitives should also work;
they're mapped to mutexes (mutices?) and NOP respectively -- but they're
largely untested because the eCos tests so far have all been
single-threaded.

> 2 - does jffs2 need defragmentation functionnality ? If yes how to use this
> service if it's exist.

JFFS2 doesn't need defragmentation. However, if you're using a
thread-capable build of eCos you could usefully implement the background
garbage collection thread for eCos. Take a look at background.c and make
a background-ecos.c which does something similar.

-- 
dwmw2