1 files changed, 16 insertions, 4 deletions
diff --git a/src/third_party/wiredtiger/src/include/hardware.h b/src/third_party/wiredtiger/src/include/hardware.h
index 0e52818ae05..2530659db21 100644
--- a/src/third_party/wiredtiger/src/include/hardware.h
+++ b/src/third_party/wiredtiger/src/include/hardware.h
@@ -55,7 +55,19 @@
 #else
 #define	WT_CACHE_LINE_ALIGNMENT	64
 #endif
-#define	WT_CACHE_LINE_ALIGNMENT_VERIFY(session, a)			\
-	WT_ASSERT(session,						\
-	    WT_PTRDIFF(&(a)[1], &(a)[0]) >= WT_CACHE_LINE_ALIGNMENT &&	\
-	    WT_PTRDIFF(&(a)[1], &(a)[0]) % WT_CACHE_LINE_ALIGNMENT == 0)
+
+/*
+ * Pad a structure so an array of structures get separate cache lines.
+ *
+ * Note that we avoid compiler structure alignment because that requires
+ * allocating aligned blocks of memory, and alignment pollutes any other type
+ * that contains an aligned field.  It is possible that a hot field positioned
+ * before this one will be on the same cache line, but not if it is also
+ * padded.
+ *
+ * This alignment has a small impact on portability as well, as we are using an
+ * anonymous union here which is supported under C11, earlier versions of
+ * the GNU standard, and MSVC versions as early as 2003.
+ */
+#define	WT_CACHE_LINE_PAD_BEGIN union { struct {
+#define	WT_CACHE_LINE_PAD_END   }; char __padding[WT_CACHE_LINE_ALIGNMENT]; };