1 files changed, 88 insertions, 0 deletions
diff --git a/include/my_global.h b/include/my_global.h
index 61850931a8e..5a93e47a608 100644
--- a/include/my_global.h
+++ b/include/my_global.h
@@ -101,6 +101,94 @@
 #define unlikely(x)	__builtin_expect((x),0)
 
 
+/*
+  The macros below are useful in optimising places where it has been
+  discovered that cache misses stall the process and where a prefetch
+  of the cache line can improve matters. This is available in GCC 3.1.1
+  and later versions.
+  PREFETCH_READ says that addr is going to be used for reading and that
+  it is to be kept in caches if possible for a while
+  PREFETCH_WRITE also says that the item to be cached is likely to be
+  updated.
+  The *LOCALITY scripts are also available for experimentation purposes
+  mostly and should only be used if they are verified to improve matters.
+  For more input see GCC manual (available in GCC 3.1.1 and later)
+*/
+
+#if (__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR > 10)
+#define PREFETCH_READ(addr) __builtin_prefetch(addr, 0, 3)
+#define PREFETCH_WRITE(addr) \
+  __builtin_prefetch(addr, 1, 3)
+#define PREFETCH_READ_LOCALITY(addr, locality) \
+  __builtin_prefetch(addr, 0, locality)
+#define PREFETCH_WRITE_LOCALITY(addr, locality) \
+  __builtin_prefetch(addr, 1, locality)
+#else
+#define PREFETCH_READ(addr)
+#define PREFETCH_READ_LOCALITY(addr, locality)
+#define PREFETCH_WRITE(addr)
+#define PREFETCH_WRITE_LOCALITY(addr, locality)
+#endif
+
+/*
+  The following macro is used to ensure that code often used in most
+  SQL statements and definitely for parts of the SQL processing are
+  kept in a code segment by itself. This has the advantage that the
+  risk of common code being overlapping in caches of the CPU is less.
+  This can be a cause of big performance problems.
+  Routines should be put in this category with care and when they are
+  put there one should also strive to make as much of the error handling
+  as possible (or uncommon code of the routine) to execute in a
+  separate method to avoid moving to much code to this code segment.
+
+  It is very easy to use, simply add HOT_METHOD at the end of the
+  function declaration.
+  For more input see GCC manual (available in GCC 2.95 and later)
+*/
+
+#if (__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR > 94)
+#define HOT_METHOD \
+  __attribute__ ((section ("hot_code_section")))
+#else
+#define HOT_METHOD
+#endif
+
+/*
+  The following macro is used to ensure that popular global variables
+  are located next to each other to avoid that they contend for the
+  same cache lines.
+
+  It is very easy to use, simply add HOT_DATA at the end of the declaration
+  of the variable, the variable must be initialised because of the way
+  that linker works so a declaration using HOT_DATA should look like:
+  uint global_hot_data HOT_DATA = 0;
+  For more input see GCC manual (available in GCC 2.95 and later)
+*/
+
+#if (__GNUC__ > 2) || (__GNUC__ == 2 && __GNUC_MINOR > 94)
+#define HOT_DATA \
+  __attribute__ ((section ("hot_data_section")))
+#else
+#define HOT_DATA
+#endif
+
+
+/*
+  The following macros are used to control inlining a bit more than
+  usual. These macros are used to ensure that inlining always or
+  never occurs (independent of compilation mode).
+  For more input see GCC manual (available in GCC 3.1.1 and later)
+*/
+
+#if (__GNUC__ > 3) || (__GNUC__ == 3 && __GNUC_MINOR > 10)
+#define ALWAYS_INLINE __attribute__ ((always_inline))
+#define NEVER_INLINE __attribute__ ((noinline))
+#else
+#define ALWAYS_INLINE
+#define NEVER_INLINE
+#endif
+
+
 /* Fix problem with S_ISLNK() on Linux */
 #if defined(TARGET_OS_LINUX)
 #undef  _GNU_SOURCE