Re: [patch] x86_64: fix sched_clock()

From: Peter Zijlstra
Date: Fri May 25 2007 - 04:15:29 EST


On Fri, 2007-05-25 at 09:54 +0200, Ingo Molnar wrote:
> Subject: [patch] x86_64: fix sched_clock()
> From: Ingo Molnar <mingo@xxxxxxx>
>
> sched_clock() is totally broken on x86_64, because it is not defined by
> the architecture at all! It fell the victim to the opaqueness of
> __attribute__((weak)) and to non-testing.
>
> the i386 version was supposed to be used. This patch fixes that. Booted
> and tested on x86_64 and i386.
>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

This does indeed solve my issue.

> ---
> arch/x86_64/kernel/Makefile | 3 ++-
> include/asm-x86_64/tsc.h | 5 +++++
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> Index: linux-cfs-2.6.22-rc2-mm1.q/arch/x86_64/kernel/Makefile
> ===================================================================
> --- linux-cfs-2.6.22-rc2-mm1.q.orig/arch/x86_64/kernel/Makefile
> +++ linux-cfs-2.6.22-rc2-mm1.q/arch/x86_64/kernel/Makefile
> @@ -9,7 +9,7 @@ obj-y := process.o signal.o entry.o trap
> x8664_ksyms.o i387.o syscall.o vsyscall.o \
> setup64.o bootflag.o e820.o reboot.o quirks.o i8237.o \
> pci-dma.o pci-nommu.o alternative.o hpet.o tsc.o bugs.o \
> - perfctr-watchdog.o
> + perfctr-watchdog.o sched-clock.o
>
> obj-$(CONFIG_STACKTRACE) += stacktrace.o
> obj-$(CONFIG_X86_MCE) += mce.o therm_throt.o
> @@ -49,6 +49,7 @@ obj-y += pcspeaker.o
>
> CFLAGS_vsyscall.o := $(PROFILING) -g0
>
> +sched-clock-y += ../../i386/kernel/sched-clock.o
> therm_throt-y += ../../i386/kernel/cpu/mcheck/therm_throt.o
> bootflag-y += ../../i386/kernel/bootflag.o
> legacy_serial-y += ../../i386/kernel/legacy_serial.o
> Index: linux-cfs-2.6.22-rc2-mm1.q/include/asm-x86_64/tsc.h
> ===================================================================
> --- linux-cfs-2.6.22-rc2-mm1.q.orig/include/asm-x86_64/tsc.h
> +++ linux-cfs-2.6.22-rc2-mm1.q/include/asm-x86_64/tsc.h
> @@ -1 +1,6 @@
> #include <asm-i386/tsc.h>
> +
> +/*
> + * To be able to share sched-clock.c between i386 and x86_64:
> + */
> +#define tsc_disable 0
>

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