Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/…

…linux/kernel/git/tip/linux-2.6-tip * '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
mariux64 · Nov 8, 2008 · a622cf6 · a622cf6
2 parents af3e48f + 7cbaef9
commit a622cf6
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Showing 3 changed files with 8 additions and 4 deletions.
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
@@ -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);
 }

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
@@ -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);

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
@@ -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