diff --git a/Makefile.am b/Makefile.am
index 4a9de2b..ddcbbf8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,7 +10,7 @@ umem_test2_SOURCES = umem_test2.c
 umem_test2_LDADD = -lumem
 
 umem_test3_SOURCES = umem_test3.c
-umem_test3_LDADD = -lumem
+umem_test3_LDADD = -lumem -lumem_malloc
 
 libumem_la_SOURCES =	init_lib.c \
 			umem_agent_support.c \
diff --git a/configure.ac b/configure.ac
index b56d557..6166f4b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7,8 +7,23 @@ AC_PROG_LIBTOOL
 
 AC_C_INLINE
 
-AC_CHECK_HEADERS([sys/mman.h sys/sysmacros.h sys/time.h])
-AC_CHECK_FUNCS([issetugid])
+AC_MSG_CHECKING([whether pthread_mutex_t is larger than 24 bytes])
+AC_TRY_RUN( 
+  [   
+#include <pthread.h>
+int main(void){return (sizeof(pthread_mutex_t) > 24);}
+  ],
+  [AC_MSG_RESULT(yes)],
+  [
+    AC_MSG_RESULT(no)
+    AC_DEFINE(UMEM_PTHREAD_MUTEX_TOO_BIG, [1], [need bigger cache])
+    AC_MSG_WARN([*** increasing umem cpu cache size to compensate.])
+  ]
+) 
+
+
+AC_CHECK_HEADERS([sys/mman.h sys/sysmacros.h sys/time.h malloc.h])
+AC_CHECK_FUNCS([issetugid mallinfo malloc_stats])
 
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_FILES([Makefile Doxyfile umem.spec])
diff --git a/umem_test3.c b/umem_test3.c
index bcbb231..88845d1 100644
--- a/umem_test3.c
+++ b/umem_test3.c
@@ -1,14 +1,35 @@
+#include "config.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#if defined(HAVE_MALLOC_H) && defined(HAVE_MALLINFO)
+#include <malloc.h>
+#endif
+
+static void minfo(void)
+{
+#if defined(HAVE_MALLOC_H) && defined(HAVE_MALLINFO)
+  struct mallinfo mi;
+  mi = mallinfo();
+  printf(" fordblks = %d\n", mi.fordblks);
+  malloc_stats();
+  printf("\n");
+#endif
+}
+
 int
 main (void)
 {
   char *p;
 
+  minfo();
   p = malloc(10);
   free(p);
+  minfo();
 
   return EXIT_SUCCESS;
 }
+
+/* vim:ts=2:sw=2:et:
+ */