[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>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 8090a0a46882..46bf556efc30 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -1042,6 +1042,7 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
         if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
             (c->x86 == 0x6 && c->x86_model >= 0x0e))
                 set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability);
+        set_bit(X86_FEATURE_SYNC_RDTSC, &c->x86_capability);
         c->x86_max_cores = intel_num_cpu_cores(c);
 
         srat_detect_node();