Messages in this thread | | | From | Dieter Nützel <> | Subject | Re: [ACPI] ACPI mentioned on lwn.net/kernel | Date | Mon, 28 Jan 2002 00:58:47 +0100 |
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On Sunday, 27. January 2002 13:56, Martin Dalecki wrote: > Linus Torvalds wrote: > > > In article <jeelkes8y5.fsf@sykes.suse.de>, > > Andreas Schwab <schwab@suse.de> wrote: > > > >>|> > >>|> Storing 30% less executable pages in memory? Reading 30% less > >>|> executable > >>|> pages off the disk? > >> > >>These are all startup costs that are lost in the noise the longer the > >>program runs. > >> > > > >That's a load of bull. > > > >Startup costs tend to _dominate_ most applications, except for > >benchmarks, scientific loads and games/multimedia. > > > Well the situation is in fact even more embarassing if you do true > benchmarking on really long running (well that's relative of course) > applications. I personaly did once in a time a benchmarking on the good old > tex running trhough a few hundert pages long document. Well the -O2 version > was actually about 15% *SLOWER* then the -Os version. That's becouse in real > world applications, which don't do numerical calculations but most of the > time they do "decision taking" the whole mulitpipline sceduling get's > outwighted by the simple cache pressure thing by *far*. > > The whole GCC developement is badly misguided on this for *sure*. They > develop for numerics where most programs are kind of doing a > controlling/decision taking job. > Well I know I should try this with the kernel one time...
I can second that. Now that I'm running AMD Athlon's since August 1999 I found during 3D development/benchmarking (OpenGL/Mesa) that the following GCC flags are "best" for Athlon/Duron with gcc-2.95.3:
-O -mcpu=k6 -pipe -mpreferred-stack-boundary=2 -malign-functions=4 -fschedule-insns2 -fexpensive-optimizations
I even compile the whole kernel with a little different flags setting. It is smaller and "faster" with them.
HOSTCFLAGS = -Wall -Wstrict-prototypes -O -fomit-frame-pointer -mcpu=k6 -pipe -mpreferred-stack-boundary=2 -malign-functions=4 -fschedule-insns2 -fexpensive-optimizations
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes -Wno-trigraphs -O \ -fomit-frame-pointer -fno-strict-aliasing -fno-common
linux/arch/i386/Makefile: ifdef CONFIG_MK7 CFLAGS += $(shell if $(CC) -march=athlon -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-march=athlon"; else echo "-mcpu=k6 -pipe -mpreferred-stack-boundary=2 -malign-functions=4 -fschedule-insns2 -fexpensive-optimizations"; fi) endif
Regards, Dieter
-- Dieter Nützel Graduate Student, Computer Science
University of Hamburg Department of Computer Science @home: Dieter.Nuetzel@hamburg.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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