Re: [patch] measurements, numbers about CONFIG_OPTIMIZE_INLINING=y impact

H. Peter Anvin
2009-01-09T19:21:31Z

Richard Guenther wrote:
> On Fri, Jan 9, 2009 at 8:21 PM, Andi Kleen <andi@firstfloor.org> wrote:
>>> GCC 4.3 should be good in compiling the
>>> kernel with default -Os settings.
>> It's unfortunately not. It doesn't inline a lot of simple asm() inlines
>> for example.
>
> Reading Ingos posting with the actual numbers states the opposite.
>

Well, Andi's patch forcing inlining of the bitops chops quite a bit of
size off the kernel, so there is clearly room for improvement. From my
post yesterday:

: voreg 64 ; size o.*/vmlinux
text data bss dec hex filename
57590217 24940519 15560504 98091240 5d8c0e8 o.andi/vmlinux
59421552 24912223 15560504 99894279 5f44407 o.noopt/vmlinux
57700527 24950719 15560504 98211750 5da97a6 o.opty/vmlinux

110 KB of code size reduction by force-inlining the small bitops.

-hpa