Add the --disable-munmap option.
Add the --disable-munmap option, remove the configure test that
attempted to detect the VM allocation quirk known to exist on Linux
x86[_64], and make --disable-munmap implicit on Linux.
diff --git a/INSTALL b/INSTALL
index a5942ec..04671a1 100644
--- a/INSTALL
+++ b/INSTALL
@@ -108,6 +108,13 @@
released in bulk, thus reducing the total number of mutex operations. See
the "opt.tcache" option for usage details.
+--disable-munmap
+ Disable virtual memory deallocation via munmap(2); instead keep track of
+ the virtual memory for later use. munmap() is disabled by default (i.e.
+ --disable-munmap is implied) on Linux, which has a quirk in its virtual
+ memory allocation algorithm that causes semi-permanent VM map holes under
+ normal jemalloc operation.
+
--enable-dss
Enable support for page allocation/deallocation via sbrk(2), in addition to
mmap(2).
diff --git a/configure.ac b/configure.ac
index 5d0c726..90235f7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -206,6 +206,7 @@
dnl Define cpp macros in CPPFLAGS, rather than doing AC_DEFINE(macro), since the
dnl definitions need to be seen before any headers are included, which is a pain
dnl to make happen otherwise.
+default_munmap="1"
case "${host}" in
*-*-darwin*)
CFLAGS="$CFLAGS -fno-common"
@@ -230,6 +231,7 @@
AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED], [ ])
AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
RPATH="-Wl,-rpath,"
+ default_munmap="0"
;;
*-*-netbsd*)
AC_MSG_CHECKING([ABI])
@@ -667,6 +669,22 @@
fi
AC_SUBST([enable_tcache])
+dnl Enable VM deallocation via munmap() by default.
+AC_ARG_ENABLE([munmap],
+ [AS_HELP_STRING([--disable-munmap], [Disable VM deallocation via munmap(2)])],
+[if test "x$enable_munmap" = "xno" ; then
+ enable_munmap="0"
+else
+ enable_munmap="1"
+fi
+],
+[enable_munmap="${default_munmap}"]
+)
+if test "x$enable_munmap" = "x1" ; then
+ AC_DEFINE([JEMALLOC_MUNMAP], [ ])
+fi
+AC_SUBST([enable_munmap])
+
dnl Do not enable allocation from DSS by default.
AC_ARG_ENABLE([dss],
[AS_HELP_STRING([--enable-dss], [Enable allocation from DSS])],
@@ -817,72 +835,6 @@
AC_MSG_ERROR([cannot determine value for STATIC_PAGE_SHIFT])
fi
-dnl Determine whether common sequences of mmap()/munmap() calls will leave
-dnl semi-permanent VM map holes. If so, disable munmap.
-AC_CACHE_CHECK([whether munmap() leaves semi-permanent VM map holes],
- [je_cv_vmmap_hole],
- AC_RUN_IFELSE([AC_LANG_PROGRAM(
-[[#include <stdio.h>
-#include <stdlib.h>
-#include <sys/mman.h>
-
-#define MMAP_SIZE ((size_t)(1U << 22))
-
-static void *
-do_mmap(size_t size)
-{
- void *ret;
-
- ret = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1,
- 0);
- if (ret == MAP_FAILED) {
- fprintf(stderr, "mmap() error\n");
- exit(1);
- }
-
- return (ret);
-}
-
-static void
-do_munmap(void *ptr, size_t size)
-{
- if (munmap(ptr, size) == -1) {
- fprintf(stderr, "munmap() error\n");
- exit(1);
- }
-}
-]],
-[[
- void *p0, *p1, *p2, *p3, *p4;
- FILE *f;
-
- f = fopen("conftest.out", "w");
- if (f == NULL)
- exit(1);
-
- p0 = do_mmap(MMAP_SIZE);
- p1 = do_mmap(MMAP_SIZE);
- p2 = do_mmap(MMAP_SIZE);
- do_munmap(p1, MMAP_SIZE);
- p3 = do_mmap(MMAP_SIZE * 2);
- do_munmap(p3, MMAP_SIZE * 2);
- p4 = do_mmap(MMAP_SIZE);
- if (p4 != p1) {
- fprintf(stderr, "Hoped for %p, got %p\n", p1, p4);
- fprintf(stderr, "%p..%p..%p..%p..%p\n", p0, p1, p2, p3, p4);
- fprintf(f, "yes\n");
- } else
- fprintf(f, "no\n");
-
- fclose(f);
- return (0);
-]])],
- [je_cv_vmmap_hole=`cat conftest.out`],
- [je_cv_vmmap_hole=unknown]))
-if test "x$je_cv_vmmap_hole" = "xno" ; then
- AC_DEFINE([JEMALLOC_MUNMAP], [ ])
-fi
-
dnl ============================================================================
dnl jemalloc configuration.
dnl
@@ -1198,6 +1150,7 @@
AC_MSG_RESULT([utrace : ${enable_utrace}])
AC_MSG_RESULT([valgrind : ${enable_valgrind}])
AC_MSG_RESULT([xmalloc : ${enable_xmalloc}])
+AC_MSG_RESULT([munmap : ${enable_munmap}])
AC_MSG_RESULT([dss : ${enable_dss}])
AC_MSG_RESULT([lazy_lock : ${enable_lazy_lock}])
AC_MSG_RESULT([tls : ${enable_tls}])
diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index ee60c98..98d0ba4 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -652,6 +652,16 @@
<varlistentry>
<term>
+ <mallctl>config.munmap</mallctl>
+ (<type>bool</type>)
+ <literal>r-</literal>
+ </term>
+ <listitem><para><option>--enable-munmap</option> was specified during
+ build configuration.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>
<mallctl>config.prof</mallctl>
(<type>bool</type>)
<literal>r-</literal>
diff --git a/src/ctl.c b/src/ctl.c
index 6be4056..a6a02cc 100644
--- a/src/ctl.c
+++ b/src/ctl.c
@@ -50,6 +50,7 @@
CTL_PROTO(config_dss)
CTL_PROTO(config_fill)
CTL_PROTO(config_lazy_lock)
+CTL_PROTO(config_munmap)
CTL_PROTO(config_prof)
CTL_PROTO(config_prof_libgcc)
CTL_PROTO(config_prof_libunwind)
@@ -176,6 +177,7 @@
{NAME("dss"), CTL(config_dss)},
{NAME("fill"), CTL(config_fill)},
{NAME("lazy_lock"), CTL(config_lazy_lock)},
+ {NAME("munmap"), CTL(config_munmap)},
{NAME("prof"), CTL(config_prof)},
{NAME("prof_libgcc"), CTL(config_prof_libgcc)},
{NAME("prof_libunwind"), CTL(config_prof_libunwind)},
@@ -1087,6 +1089,7 @@
CTL_RO_BOOL_CONFIG_GEN(config_dss)
CTL_RO_BOOL_CONFIG_GEN(config_fill)
CTL_RO_BOOL_CONFIG_GEN(config_lazy_lock)
+CTL_RO_BOOL_CONFIG_GEN(config_munmap)
CTL_RO_BOOL_CONFIG_GEN(config_prof)
CTL_RO_BOOL_CONFIG_GEN(config_prof_libgcc)
CTL_RO_BOOL_CONFIG_GEN(config_prof_libunwind)