Add the --disable-thp option to support cross compiling.

This resolves #669.

INSTALL.md

@@ -157,6 +157,11 @@ any of the following arguments (not a definitive list) to 'configure':
     Statically link against the specified libunwind.a rather than dynamically
     linking with -lunwind.
 
+* `--disable-thp`
+
+    Disable transparent huge page (THP) integration.  This option can be useful
+    when cross compiling.
+
 * `--disable-fill`
 
     Disable support for junk/zero filling of memory.  See the "opt.junk" and
@@ -224,7 +229,7 @@ any of the following arguments (not a definitive list) to 'configure':
 * `--with-lg-page-sizes=<lg-page-sizes>`
 
     Specify the comma-separated base 2 logs of the page sizes to support.  This
-    option may be useful when cross-compiling in combination with
+    option may be useful when cross compiling in combination with
     `--with-lg-page`, but its primary use case is for integration with FreeBSD's
     libc, wherein jemalloc is embedded.
 

configure.ac

@@ -1792,10 +1792,28 @@ if test "x${je_cv_madvise}" = "xyes" ; then
 	madvise((void *)0, 0, MADV_HUGEPAGE);
 	madvise((void *)0, 0, MADV_NOHUGEPAGE);
 ], [je_cv_thp])
-  if test "x${je_cv_thp}" = "xyes" ; then
+fi
+
+dnl Enable transparent huge page support by default.
+AC_ARG_ENABLE([thp],
+  [AS_HELP_STRING([--disable-thp],
+                  [Disable transparent huge page support])],
+[if test "x$enable_thp" = "xno" -o "x${je_cv_thp}" != "xyes" ; then
+  enable_thp="0"
+else
+  enable_thp="1"
+fi
+],
+[if test "x${je_cv_thp}" = "xyes" ; then
+  enable_thp="1"
+else
+  enable_thp="0"
+fi
+])
+if test "x$enable_thp" = "x1" ; then
   AC_DEFINE([JEMALLOC_THP], [ ])
 fi
-fi
+AC_SUBST([enable_thp])
 
 dnl ============================================================================
 dnl Check whether __sync_{add,sub}_and_fetch() are available despite
@@ -2141,6 +2159,7 @@ AC_MSG_RESULT([prof               : ${enable_prof}])
 AC_MSG_RESULT([prof-libunwind     : ${enable_prof_libunwind}])
 AC_MSG_RESULT([prof-libgcc        : ${enable_prof_libgcc}])
 AC_MSG_RESULT([prof-gcc           : ${enable_prof_gcc}])
+AC_MSG_RESULT([thp                : ${enable_thp}])
 AC_MSG_RESULT([fill               : ${enable_fill}])
 AC_MSG_RESULT([utrace             : ${enable_utrace}])
 AC_MSG_RESULT([xmalloc            : ${enable_xmalloc}])

doc/jemalloc.xml.in

@@ -849,6 +849,17 @@ mallctl("arena." STRINGIFY(MALLCTL_ARENAS_ALL) ".decay",
         build configuration.</para></listitem>
       </varlistentry>
 
+      <varlistentry id="config.thp">
+        <term>
+          <mallctl>config.thp</mallctl>
+          (<type>bool</type>)
+          <literal>r-</literal>
+        </term>
+        <listitem><para><option>--disable-thp</option> was not specified
+        during build configuration, and the system supports transparent huge
+        page manipulation.</para></listitem>
+      </varlistentry>
+
       <varlistentry id="config.utrace">
         <term>
           <mallctl>config.utrace</mallctl>

include/jemalloc/internal/jemalloc_internal_defs.h.in

@@ -269,8 +269,8 @@
 #undef JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS
 
 /*
- * Defined if transparent huge pages are supported via the MADV_[NO]HUGEPAGE
- * arguments to madvise(2).
+ * Defined if transparent huge pages (THPs) are supported via the
+ * MADV_[NO]HUGEPAGE arguments to madvise(2), and THP support is enabled.
  */
 #undef JEMALLOC_THP
 

include/jemalloc/internal/jemalloc_preamble.h.in

@@ -111,6 +111,13 @@ static const bool config_stats =
     false
 #endif
     ;
+static const bool config_thp =
+#ifdef JEMALLOC_THP
+    true
+#else
+    false
+#endif
+    ;
 static const bool config_tls =
 #ifdef JEMALLOC_TLS
     true
@@ -139,13 +146,6 @@ static const bool config_cache_oblivious =
     false
 #endif
     ;
-static const bool have_thp =
-#ifdef JEMALLOC_THP
-    true
-#else
-    false
-#endif
-    ;
 #ifdef JEMALLOC_HAVE_SCHED_GETCPU
 /* Currently percpu_arena depends on sched_getcpu. */
 #define JEMALLOC_PERCPU_ARENA

src/ctl.c

@@ -73,6 +73,7 @@ CTL_PROTO(config_prof)
 CTL_PROTO(config_prof_libgcc)
 CTL_PROTO(config_prof_libunwind)
 CTL_PROTO(config_stats)
+CTL_PROTO(config_thp)
 CTL_PROTO(config_utrace)
 CTL_PROTO(config_xmalloc)
 CTL_PROTO(opt_abort)
@@ -263,6 +264,7 @@ static const ctl_named_node_t	config_node[] = {
 	{NAME("prof_libgcc"),	CTL(config_prof_libgcc)},
 	{NAME("prof_libunwind"), CTL(config_prof_libunwind)},
 	{NAME("stats"),		CTL(config_stats)},
+	{NAME("thp"),		CTL(config_thp)},
 	{NAME("utrace"),	CTL(config_utrace)},
 	{NAME("xmalloc"),	CTL(config_xmalloc)}
 };
@@ -1544,6 +1546,7 @@ CTL_RO_CONFIG_GEN(config_prof, bool)
 CTL_RO_CONFIG_GEN(config_prof_libgcc, bool)
 CTL_RO_CONFIG_GEN(config_prof_libunwind, bool)
 CTL_RO_CONFIG_GEN(config_stats, bool)
+CTL_RO_CONFIG_GEN(config_thp, bool)
 CTL_RO_CONFIG_GEN(config_utrace, bool)
 CTL_RO_CONFIG_GEN(config_xmalloc, bool)
 

src/stats.c

@@ -725,6 +725,7 @@ stats_general_print(void (*write_cb)(void *, const char *), void *cbopaque,
 	CONFIG_WRITE_BOOL_JSON(prof_libgcc, ",")
 	CONFIG_WRITE_BOOL_JSON(prof_libunwind, ",")
 	CONFIG_WRITE_BOOL_JSON(stats, ",")
+	CONFIG_WRITE_BOOL_JSON(thp, ",")
 	CONFIG_WRITE_BOOL_JSON(utrace, ",")
 	CONFIG_WRITE_BOOL_JSON(xmalloc, "")
 

test/unit/pages.c

@@ -11,7 +11,7 @@ TEST_BEGIN(test_pages_huge) {
 	assert_ptr_not_null(pages, "Unexpected pages_map() error");
 
 	hugepage = (void *)(ALIGNMENT_CEILING((uintptr_t)pages, HUGEPAGE));
-	assert_b_ne(pages_huge(hugepage, HUGEPAGE), have_thp,
+	assert_b_ne(pages_huge(hugepage, HUGEPAGE), config_thp,
 	    "Unexpected pages_huge() result");
 	assert_false(pages_nohuge(hugepage, HUGEPAGE),
 	    "Unexpected pages_nohuge() result");