diff --git a/common_x86_64.h b/common_x86_64.h
index 7461aaf60..62e138e34 100644
--- a/common_x86_64.h
+++ b/common_x86_64.h
@@ -60,8 +60,13 @@
 #endif
 */
 
-#define MB
-#define WMB
+#ifdef __GNUC__
+#define MB do { __asm__ __volatile__("": : :"memory"); } while (0)
+#define WMB do { __asm__ __volatile__("": : :"memory"); } while (0)
+#else
+#define MB do {} while (0)
+#define WMB do {} while (0)
+#endif
 
 static void __inline blas_lock(volatile BLASULONG *address){
 
diff --git a/driver/level3/level3_thread.c b/driver/level3/level3_thread.c
index 4ab1ee8cc..aeb5e6ed4 100644
--- a/driver/level3/level3_thread.c
+++ b/driver/level3/level3_thread.c
@@ -91,11 +91,7 @@
 #endif
 
 typedef struct {
-#if __STDC_VERSION__ >= 201112L
-_Atomic
-#else  
   volatile
-#endif
    BLASLONG working[MAX_CPU_NUMBER][CACHE_LINE_SIZE * DIVIDE_RATE];
 } job_t;
 
@@ -351,7 +347,7 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,
       /* Make sure if no one is using workspace */
       START_RPCC();
       for (i = 0; i < args -> nthreads; i++)
-	while (job[mypos].working[i][CACHE_LINE_SIZE * bufferside]) {YIELDING;};
+	while (job[mypos].working[i][CACHE_LINE_SIZE * bufferside]) {YIELDING;MB;};
       STOP_RPCC(waiting1);
 
 #if defined(FUSED_GEMM) && !defined(TIMING)
@@ -413,7 +409,7 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,
 
 	  /* Wait until other region of B is initialized */
 	  START_RPCC();
-	  while(job[current].working[mypos][CACHE_LINE_SIZE * bufferside] == 0) {YIELDING;};
+	  while(job[current].working[mypos][CACHE_LINE_SIZE * bufferside] == 0) {YIELDING;MB;};
 	  STOP_RPCC(waiting2);
 
           /* Apply kernel with local region of A and part of other region of B */
@@ -431,6 +427,7 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,
         /* Clear synchronization flag if this thread is done with other region of B */
 	if (m_to - m_from == min_i) {
 	  job[current].working[mypos][CACHE_LINE_SIZE * bufferside] &= 0;
+	  WMB;
 	}
       }
     } while (current != mypos);
@@ -492,7 +489,7 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,
   START_RPCC();
   for (i = 0; i < args -> nthreads; i++) {
     for (js = 0; js < DIVIDE_RATE; js++) {
-      while (job[mypos].working[i][CACHE_LINE_SIZE * js] ) {YIELDING;};
+      while (job[mypos].working[i][CACHE_LINE_SIZE * js] ) {YIELDING;MB;};
     }
   }
   STOP_RPCC(waiting3);
@@ -658,8 +655,8 @@ static int gemm_driver(blas_arg_t *args, BLASLONG *range_m, BLASLONG
     }
 
     /* Clear synchronization flags */
-    for (i = 0; i < MAX_CPU_NUMBER; i++) {
-      for (j = 0; j < MAX_CPU_NUMBER; j++) {
+    for (i = 0; i < nthreads; i++) {
+      for (j = 0; j < nthreads; j++) {
 	for (k = 0; k < DIVIDE_RATE; k++) {
 	  job[i].working[j][CACHE_LINE_SIZE * k] = 0;
 	}
diff --git a/param.h b/param.h
index 49a5e85e8..cfa4bba5c 100644
--- a/param.h
+++ b/param.h
@@ -1507,7 +1507,7 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define SYMV_P  8
 
-#define SWITCH_RATIO	4
+#define SWITCH_RATIO	32
 
 #ifdef ARCH_X86
 
@@ -1626,7 +1626,7 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define SYMV_P  8
 
-#define SWITCH_RATIO	4
+#define SWITCH_RATIO	32
 
 #ifdef ARCH_X86