On Mon, 3 Mar 2008 13:13:35 +0100 Ingo Molnar <mingo@xxxxxxx> wrote: > > * Ingo Molnar <mingo@xxxxxxx> wrote: > > > > > no, what we should nuke is this always_inline definition. That > > > > was always the intention of FORCED_INLINE, and the removal of > > > > FORCED_INLINE was to _remove the forcing_, not to make it > > > > unconditional. > > > > > > It was always unconditional, and neither adding, toggling nor > > > removing of CONFIG_FORCED_INLINING changed this invariant. > > > > > > And what we should do is to attack the excessive wrong usage of > > > inlines in .c files, not messing with a global #define in a way > > > that the results on 24 architectures with 7 different releases of > > > gcc would be unpredictable. > > > > i see, so you never properly reported and fixed it because you > > prefer a 1000 small crappy changes over one change. You could have > > significantly contributed to truly making Linux smaller, but you > > decided not to do it. > > > > and i disagree with your notion that flipping it around is risky in > > any unacceptable or unmanageable way. It has far less risks on the > > compiler than say CONFIG_CC_OPTIMIZE_FOR_SIZE. It has far less > > risks than changing to a new compiler version. Why you think it's > > "unpredictable" is a mystery to me. > > > > It almost seems to me you were happy with having that bug in the > > kernel? Please tell me that i'm wrong about that impression! > > > > i'll reinstate this .config option and let it do the right thing. > > Forced inlining was supposed to be _phased out_, not phased in. > > i just implemented the trivial fix below and it gave me a massive, > 2.3% text size reduction (!) on a typical .config. That's more than > 120K shaved off the vmlinux. > > Why, despite being aware of this bug, you never fixed this properly > is a mystery to me - this is more .text size savings than you have > done so far with all your uninlining patches of the past few years > combined, and it's probably more than you could have achieved in the > next 5 years. > > Ingo > > ----------------------> > Subject: x86: phase out forced inlining > From: Ingo Molnar <mingo@xxxxxxx> > Date: Mon Mar 03 12:38:52 CET 2008 > > allow gcc to optimize the kernel image's size by uninlining > functions that have been marked 'inline'. Previously gcc was > forced by Linux to always-inline these functions via a gcc > attribute: > > #define inline inline __attribute__((always_inline)) > > Especially when the user has already selected > CONFIG_OPTIMIZE_FOR_SIZE=y this can make a huge difference in > kernel image size (using a standard Fedora .config): > > text data bss dec hex filename > 5613924 562708 3854336 10030968 990f78 vmlinux.before > 5486689 562708 3854336 9903733 971e75 vmlinux.after > > that's a 2.3% text size reduction (!). > > Signed-off-by: Ingo Molnar <mingo@xxxxxxx> > --- > arch/x86/Kconfig.debug | 13 +++++++++++++ > arch/x86/configs/i386_defconfig | 1 + > arch/x86/configs/x86_64_defconfig | 1 + > include/linux/compiler-gcc.h | 12 +++++++++--- > 4 files changed, 24 insertions(+), 3 deletions(-) > > Index: linux-x86.q/arch/x86/Kconfig.debug > =================================================================== > --- linux-x86.q.orig/arch/x86/Kconfig.debug eh.. we ALREADY HAD THIS. someone seems to have removed this wronly; not forcing inline should have been the default after the removal (in 2.6.25-rc)! So lets fix it that way, rather than putting the config option back under a different name. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
