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SubjectRe: PATCH 2.4.17.2: make ext2 smaller
Martin Dalecki wrote:
>
> 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.

easily done, on the latest CONFIG_FINAL patch posted to lkml:

[jgarzik@rum linux.test]$ size vmlinux.vanilla
text data bss dec hex filename
1908047 274672 353340 2536059 26b27b vmlinux.vanilla

[jgarzik@rum linux.test]$ size vmlinux
text data bss dec hex filename
1905136 273808 352860 2531804 26a1dc vmlinux

--
Jeff Garzik | Only so many songs can be sung
Building 1024 | with two lips, two lungs, and one tongue.
MandrakeSoft | - nomeansno

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