Index: mysql-5.7.5-m15/mysys/thr_mutex.c
===================================================================
--- mysql-5.7.5-m15.orig/mysys/thr_mutex.c
+++ mysql-5.7.5-m15/mysys/thr_mutex.c
@@ -187,17 +187,26 @@ int safe_mutex_destroy(my_mutex_t *mp, c
 
 #elif defined(MY_PTHREAD_FASTMUTEX)
 
-static ulong mutex_delay(ulong delayloops)
+# if defined(__powerpc__)
+#  define MY_LOW_PRIORITY_CPU() __asm__ __volatile__ ("or 1,1,1")
+#  define MY_RESUME_PRIORITY_CPU() __asm__ __volatile__ ("or 2,2,2")
+# else
+#  define MY_LOW_PRIORITY_CPU() ((void)0)
+#  define MY_RESUME_PRIORITY_CPU() ((void)0)
+# endif
+
+#define MY_COMPILER_BARRIER() __asm__ __volatile__ ("":::"memory")
+
+static void mutex_delay(ulong delayloops)
 {
   ulong	i;
-  volatile ulong j;
 
-  j = 0;
+  MY_LOW_PRIORITY_CPU();
 
   for (i = 0; i < delayloops * 50; i++)
-    j += i;
+    MY_COMPILER_BARRIER();
 
-  return(j);
+  MY_RESUME_PRIORITY_CPU();
 }
 
 #define MY_PTHREAD_FASTMUTEX_SPINS 8