Re: PATCH 2.4.17.2: make ext2 smaller

[Martin Dalecki]

Jeff Garzik wrote:
> 
> I do not plan to submit this patch to Linus/Marcelo.
> 
> This patch applies an obvious technique to the kernel:  increase the
> amount of code compiled in a single compilation unit, to increase the
> overall knowledge the compiler has of the code, to allow for better
> optimization and dead code removal.  KDE does this, with definite
> success, though they definitely are not the first to do this.
> 
> Simply, all ext2 files are #include'd into a single file, ext2_all.c,
> and all functions and data structures are declared static.
> 
> This technique can be used in the kernel, userspace applications, and
> userspace libraries to decrease icache footprint and overall size of
> your applications.
> 
> Results from 2.4.17-pre2 plus the attached patch:  1135 bytes saved in
> vmlinux, simply from making all the functions static.
> (*.orig is prior to my patch.  kernel is P2 SMP-based)
> > [jgarzik@rum linux-e2all]$ ls -l vmlinux* arch/i386/boot/bzImage*
> > -rw-r--r--    1 jgarzik  jgarzik   1030259 Dec  2 06:18 arch/i386/boot/bzImage
> > -rw-r--r--    1 jgarzik  jgarzik   1030263 Dec  2 06:04 arch/i386/boot/bzImage.orig
> > -rwxr-xr-x    1 jgarzik  jgarzik   2814631 Dec  2 06:18 vmlinux*
> > -rwxr-xr-x    1 jgarzik  jgarzik   2815766 Dec  2 06:04 vmlinux.orig*
r

size vmlinux
and 
size vmlinux.orig

would be a bit more telling whatever the reaons of the impact is.