Index: sys/conf/NOTES
===================================================================
--- sys/conf/NOTES
+++ sys/conf/NOTES
@@ -2842,3 +2842,7 @@
 
 # Kernel support for stats(3).
 options 	STATS
+
+# Try to reduce memory usage. It may come as a tradeoff against performance
+# of multicore systems.
+#options 	COMPACT
Index: sys/conf/options
===================================================================
--- sys/conf/options
+++ sys/conf/options
@@ -1014,3 +1014,6 @@
 # gcov support
 GCOV		opt_global.h
 LINDEBUGFS
+
+# Try to reduce memory usage
+COMPACT
Index: sys/sys/cdefs.h
===================================================================
--- sys/sys/cdefs.h
+++ sys/sys/cdefs.h
@@ -241,6 +241,12 @@
 #define	__alignof(x)	__offsetof(struct { char __a; x __b; }, __b)
 #endif
 
+#ifndef	COMPACT
+#define	__aligned_if_not_compact(x)	__aligned(x)
+#else
+#define	__aligned_if_not_compact(x)
+#endif
+
 /*
  * Keywords added in C11.
  */
Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -169,7 +169,7 @@
  */
 #define	__read_mostly		__section(".data.read_mostly")
 #define	__read_frequently	__section(".data.read_frequently")
-#define	__exclusive_cache_line	__aligned(CACHE_LINE_SIZE) \
+#define	__exclusive_cache_line	__aligned_if_not_compact(CACHE_LINE_SIZE) \
 				    __section(".data.exclusive_cache_line")
 #ifdef _KERNEL
 #include <sys/param.h>		/* MAXCPU */