Re: Interest in DOC and YAFFS? --> YAFFS bootloading

Brian J. Fox
2002-09-24T17:21:50Z

From: Marc Singer <elf@buici.com>
Cc: Charles Manning <manningc2@actrix.gen.nz>, linux-mtd@lists.infradead.org,
yaffs@toby-churchill.org
Date: Tue, 24 Sep 2002 10:14:19 -0700

On Tue, Sep 24, 2002 at 09:59:03AM -0700, Russ Dill wrote:
> On Tue, 2002-09-24 at 09:53, Marc Singer wrote:
> > On Tue, Sep 24, 2002 at 12:53:36AM -0700, Russ Dill wrote:
> > >
> >
> > A question, though. I've been doing compression tests with cramfs.
> > I'm finding that gzip -9 of an ext2 filesystem produces smaller images
> > than mkcramfs. Have you ever compared the two?
>
> cramfs is meant to be lean, fast, and low on ram consumption, if you
> compress the whole thing at once, you have to load the whole thing into
> ram to read any of it, so cramfs compresses PAGE_CACHE (4096) sized
> pages at a time

That's what isn't clear. I made two filesystems with the same
contents. One cramfs and the other ext2. The ext2 filesystem
compressed was smaller than the cramfs. My understanding is that both
must be uncompressed into a ramfs to be used. If this is correct,
then the only comparable consideration is the size of the compressed
data.

No, the size of the uncompressed data is also important.

Is the ext2 system uncompressed bigger, smaller, or the same size as
the uncompressed? cramfs?

brian