Merge pull request #168 from grooverdan/10.1-MDEV-8684-UT_RELAX_CPU_isnt_relaxing

MDEV-8684 ut relax cpu isnt relaxing

2 files changed, 22 insertions, 18 deletions

diff --git a/storage/xtradb/include/ut0ut.h b/storage/xtradb/include/ut0ut.h
index 9228c25d8be..722acdb607e 100644
--- a/storage/xtradb/include/ut0ut.h
+++ b/storage/xtradb/include/ut0ut.h
@@ -80,20 +80,31 @@ private:
 
 # elif defined(HAVE_FAKE_PAUSE_INSTRUCTION)
 #  define UT_RELAX_CPU() __asm__ __volatile__ ("rep; nop")
-# elif defined(HAVE_ATOMIC_BUILTINS)
-#  define UT_RELAX_CPU() do { \
-     volatile lint	volatile_var; \
-     os_compare_and_swap_lint(&volatile_var, 0, 1); \
-   } while (0)
 # elif defined(HAVE_WINDOWS_ATOMICS)
    /* In the Win32 API, the x86 PAUSE instruction is executed by calling
    the YieldProcessor macro defined in WinNT.h. It is a CPU architecture-
    independent way by using YieldProcessor. */
 #  define UT_RELAX_CPU() YieldProcessor()
+# elif defined(__powerpc__)
+#include <sys/platform/ppc.h>
+#  define UT_RELAX_CPU() do { \
+     volatile lint      volatile_var = __ppc_get_timebase(); \
+   } while (0)
 # else
 #  define UT_RELAX_CPU() ((void)0) /* avoid warning for an empty statement */
 # endif
 
+#define UT_COMPILER_BARRIER() __asm__ __volatile__ ("":::"memory")
+
+# if defined(HAVE_HMT_PRIORITY_INSTRUCTION)
+#include <sys/platform/ppc.h>
+#  define UT_LOW_PRIORITY_CPU() __ppc_set_ppr_low()
+#  define UT_RESUME_PRIORITY_CPU() __ppc_set_ppr_med()
+# else
+#  define UT_LOW_PRIORITY_CPU() ((void)0)
+#  define UT_RESUME_PRIORITY_CPU() ((void)0)
+# endif
+
 /*********************************************************************//**
 Delays execution for at most max_wait_us microseconds or returns earlier
 if cond becomes true.
@@ -334,7 +345,7 @@ Runs an idle loop on CPU. The argument gives the desired delay
 in microseconds on 100 MHz Pentium + Visual C++.
 @return	dummy value */
 UNIV_INTERN
-ulint
+void
 ut_delay(
 /*=====*/
 	ulint	delay);	/*!< in: delay in microseconds on 100 MHz Pentium */
diff --git a/storage/xtradb/ut/ut0ut.cc b/storage/xtradb/ut/ut0ut.cc
index 4eade1fe26e..acedb56879a 100644
--- a/storage/xtradb/ut/ut0ut.cc
+++ b/storage/xtradb/ut/ut0ut.cc
@@ -46,9 +46,6 @@ Created 5/11/1994 Heikki Tuuri
 # include <string>
 #endif /* UNIV_HOTBACKUP */
 
-/** A constant to prevent the compiler from optimizing ut_delay() away. */
-UNIV_INTERN ibool	ut_always_false	= FALSE;
-
 #ifdef __WIN__
 /*****************************************************************//**
 NOTE: The Windows epoch starts from 1601/01/01 whereas the Unix
@@ -398,25 +395,21 @@ Runs an idle loop on CPU. The argument gives the desired delay
 in microseconds on 100 MHz Pentium + Visual C++.
 @return	dummy value */
 UNIV_INTERN
-ulint
+void
 ut_delay(
 /*=====*/
 	ulint	delay)	/*!< in: delay in microseconds on 100 MHz Pentium */
 {
-	ulint	i, j;
+	ulint	i;
 
-	j = 0;
+	UT_LOW_PRIORITY_CPU();
 
 	for (i = 0; i < delay * 50; i++) {
-		j += i;
 		UT_RELAX_CPU();
+		UT_COMPILER_BARRIER();
 	}
 
-	if (ut_always_false) {
-		ut_always_false = (ibool) j;
-	}
-
-	return(j);
+	UT_RESUME_PRIORITY_CPU();
 }
 #endif /* !UNIV_HOTBACKUP */