[PATCH] x86_64: On Intel CPUs don't do an additional CPU sync before RDTSC
RDTSC serialization using cpuid is not needed for Intel platforms.
This increases gettimeofday performance.
Cc: vojtech@suse.cz
Cc: rohit.seth@intel.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c
index 70a0bd1..9e51047 100644
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -66,8 +66,7 @@
(__jiffies - __wall_jiffies) * (1000000 / HZ);
if (__vxtime.mode != VXTIME_HPET) {
- sync_core();
- rdtscll(t);
+ t = get_cycles_sync();
if (t < __vxtime.last_tsc)
t = __vxtime.last_tsc;
usec += ((t - __vxtime.last_tsc) *