redonkable/alistair23-linux
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Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: optimize sched_clock() a bit
  sched: improve sched_clock() performance
This commit is contained in:
Linus Torvalds 2008-11-08 10:24:28 -08:00
parent af3e48ffce 7cbaef9c83
commit a622cf69b8
3 changed files with 8 additions and 4 deletions
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2
arch/x86/include/asm/msr.h
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@ -108,9 +108,7 @@ static __always_inline unsigned long long __native_read_tsc(void)
{
DECLARE_ARGS(val, low, high);
rdtsc_barrier();
asm volatile("rdtsc" : EAX_EDX_RET(val, low, high));
rdtsc_barrier();
return EAX_EDX_VAL(val, low, high);
}

8
arch/x86/include/asm/tsc.h
View file

@ -34,6 +34,8 @@ static inline cycles_t get_cycles(void)
static __always_inline cycles_t vget_cycles(void)
{
cycles_t cycles;
/*
* We only do VDSOs on TSC capable CPUs, so this shouldnt
* access boot_cpu_data (which is not VDSO-safe):
@ -42,7 +44,11 @@ static __always_inline cycles_t vget_cycles(void)
if (!cpu_has_tsc)
return 0;
#endif
return (cycles_t)__native_read_tsc();
rdtsc_barrier();
cycles = (cycles_t)__native_read_tsc();
rdtsc_barrier();
return cycles;
}
extern void tsc_init(void);

2
arch/x86/kernel/tsc.c
View file

@ -55,7 +55,7 @@ u64 native_sched_clock(void)
rdtscll(this_offset);
/* return the value in ns */
return cycles_2_ns(this_offset);
return __cycles_2_ns(this_offset);
}
/* We need to define a real function for sched_clock, to override the