[rt-tests PATCH v2] queuelat: use mfence for rdtsc ordering

[Marcelo Tosatti <mtosatti@xxxxxxxxxx>]

cpuid is causing register corruption: use mfence instead.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

v2: fix signed-off-by line

diff --git a/src/queuelat/queuelat.c b/src/queuelat/queuelat.c
index 2230d04..3b291f1 100644
--- a/src/queuelat/queuelat.c
+++ b/src/queuelat/queuelat.c
@@ -265,7 +265,7 @@ static inline unsigned long long __rdtscll(void)
 {
         DECLARE_ARGS(val, low, high);
 
-        asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high));
+        asm volatile("mfence; rdtsc" : EAX_EDX_RET(val, low, high));
 
         return EAX_EDX_VAL(val, low, high);
 }