1 files changed, 142 insertions, 0 deletions
diff --git a/include/my_cpu.h b/include/my_cpu.h
new file mode 100644
index 00000000..e536ff28
--- /dev/null
+++ b/include/my_cpu.h
@@ -0,0 +1,142 @@
+#ifndef MY_CPU_INCLUDED
+#define MY_CPU_INCLUDED
+/* Copyright (c) 2013, 2020, MariaDB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
+*/
+
+/* instructions for specific cpu's */
+
+/*
+  Macros for adjusting thread priority (hardware multi-threading)
+  The defines are the same ones used by the linux kernel
+*/
+
+#ifdef _ARCH_PWR8
+#include <sys/platform/ppc.h>
+/* Very low priority */
+#define HMT_very_low() __ppc_set_ppr_very_low()
+/* Low priority */
+#define HMT_low() __ppc_set_ppr_low()
+/* Medium low priority */
+#define HMT_medium_low() __ppc_set_ppr_med_low()
+/* Medium priority */
+#define HMT_medium() __ppc_set_ppr_med()
+/* Medium high priority */
+#define HMT_medium_high() __ppc_set_ppr_med_high()
+/* High priority */
+#define HMT_high() asm volatile("or 3,3,3")
+#else
+#define HMT_very_low()
+#define HMT_low()
+#define HMT_medium_low()
+#define HMT_medium()
+#define HMT_medium_high()
+#define HMT_high()
+#endif
+
+#if defined __i386__ || defined __x86_64__ || defined _WIN32
+# define HAVE_PAUSE_INSTRUCTION /* added in Intel Pentium 4 */
+#endif
+
+#ifdef _WIN32
+#elif defined HAVE_PAUSE_INSTRUCTION
+#elif defined(_ARCH_PWR8)
+#elif defined __GNUC__ && (defined __arm__ || defined __aarch64__)
+#else
+# include "my_global.h"
+# include "my_atomic.h"
+#endif
+
+static inline void MY_RELAX_CPU(void)
+{
+#ifdef _WIN32
+  /*
+    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.
+  */
+  YieldProcessor();
+#elif defined HAVE_PAUSE_INSTRUCTION
+  /*
+    According to the gcc info page, asm volatile means that the
+    instruction has important side-effects and must not be removed.
+    Also asm volatile may trigger a memory barrier (spilling all registers
+    to memory).
+  */
+#ifdef __SUNPRO_CC
+  asm ("pause" );
+#else
+  __asm__ __volatile__ ("pause");
+#endif
+#elif defined(_ARCH_PWR8)
+  __ppc_get_timebase();
+#elif defined __GNUC__ && (defined __arm__ || defined __aarch64__)
+  /* Mainly, prevent the compiler from optimizing away delay loops */
+  __asm__ __volatile__ ("":::"memory");
+#else
+  int32 var, oldval = 0;
+  my_atomic_cas32_strong_explicit(&var, &oldval, 1, MY_MEMORY_ORDER_RELAXED,
+                                  MY_MEMORY_ORDER_RELAXED);
+#endif
+}
+
+
+#ifdef HAVE_PAUSE_INSTRUCTION
+# ifdef __cplusplus
+extern "C" {
+# endif
+extern unsigned my_cpu_relax_multiplier;
+void my_cpu_init(void);
+# ifdef __cplusplus
+}
+# endif
+#else
+# define my_cpu_relax_multiplier 200
+# define my_cpu_init() /* nothing */
+#endif
+
+/*
+  LF_BACKOFF should be used to improve performance on hyperthreaded CPUs. Intel
+  recommends to use it in spin loops also on non-HT machines to reduce power
+  consumption (see e.g http://softwarecommunity.intel.com/articles/eng/2004.htm)
+
+  Running benchmarks for spinlocks implemented with InterlockedCompareExchange
+  and YieldProcessor shows that much better performance is achieved by calling
+  YieldProcessor in a loop - that is, yielding longer. On Intel boxes setting
+  loop count in the range 200-300 brought best results.
+*/
+
+static inline int LF_BACKOFF(void)
+{
+  unsigned i= my_cpu_relax_multiplier;
+  while (i--)
+    MY_RELAX_CPU();
+  return 1;
+}
+
+/**
+  Run a delay loop while waiting for a shared resource to be released.
+  @param delay originally, roughly microseconds on 100 MHz Intel Pentium
+*/
+static inline void ut_delay(unsigned delay)
+{
+  unsigned i= my_cpu_relax_multiplier / 4 * delay;
+  HMT_low();
+  while (i--)
+    MY_RELAX_CPU();
+  HMT_medium();
+}
+
+#endif