RE: [ECOS] Stress testing JFFS2

[Doug Fraser <dfraser@photuris.com>]

It becomes an interesting issue when you are using the FLASH
to store an actively updated database, which moves through
the FLASH arena at some slow but consistent rate.

Doug Fraser
dfraser@photuris.com

> -----Original Message-----
> From: Thomas Koeller [mailto:thomas.koeller@baslerweb.com]
> Sent: Wednesday, October 15, 2003 7:30 AM
> To: David Woodhouse
> Cc: ecos-discuss@sources.redhat.com; linux-mtd@lists.infradead.org
> Subject: Re: [ECOS] Stress testing JFFS2
> 
> 
> Hi David,
> 
> thanks for your quick response.
> 
> > All correct. But you miss the observation that we also keep a
> > raw_node_ref around for _obsolete_ nodes, which perhaps we 
> could avoid.
> > In fact, we do this because the raw_node_ref is in a 
> singly-linked list,
> > and it's going to be very inefficient to remove obsoleted nodes from
> > that list when they become obsolete.
> 
> I do not think this path leads anywhere I want to go. The flash size
> was chosen to meet the expected storage requirements, which means that
> at some point the flash will be filled with valid data and 
> consequently
> there will be few obsoleted nodes. I expect this to be true for most
> systems.
> 
> > Omitting the 'totlen' field should be relatively simple if 
> you're not
> > freeing obsolete refs. Observe that in 99% of cases, it's true that
> >
> > 	ref->totlen == ref_offset(ref->next_phys) - ref_offset(ref)
> >
> > Make it 100% and make me believe it, and you can remove 
> totlen from the
> > structure.
> >
> 
> I will consider that.
> 
> tk
> --------------------------------------------------
> 
> Thomas Koeller, Software Development
> 
> Basler Vision Technologies
> An der Strusbek 60-62
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> 
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> 
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