Refactor madvise(2) configuration.
Add feature tests for the MADV_FREE and MADV_DONTNEED flags to
madvise(2), so that MADV_FREE is detected and used for Linux kernel
versions 4.5 and newer. Refactor pages_purge() so that on systems which
support both flags, MADV_FREE is preferred over MADV_DONTNEED.
This resolves #387.
diff --git a/configure.ac b/configure.ac
index 72021e0..15897be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -354,7 +354,6 @@
case "${host}" in
*-*-darwin* | *-*-ios*)
abi="macho"
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
RPATH=""
LD_PRELOAD_VAR="DYLD_INSERT_LIBRARIES"
so="dylib"
@@ -367,21 +366,17 @@
*-*-freebsd*)
abi="elf"
AC_DEFINE([JEMALLOC_SYSCTL_VM_OVERCOMMIT], [ ])
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
force_lazy_lock="1"
;;
*-*-dragonfly*)
abi="elf"
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
;;
*-*-openbsd*)
abi="elf"
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
force_tls="0"
;;
*-*-bitrig*)
abi="elf"
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
;;
*-*-linux-android)
dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
@@ -389,7 +384,6 @@
abi="elf"
AC_DEFINE([JEMALLOC_HAS_ALLOCA_H])
AC_DEFINE([JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY], [ ])
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED], [ ])
AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
AC_DEFINE([JEMALLOC_C11ATOMICS])
force_tls="0"
@@ -401,7 +395,6 @@
abi="elf"
AC_DEFINE([JEMALLOC_HAS_ALLOCA_H])
AC_DEFINE([JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY], [ ])
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED], [ ])
AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
AC_DEFINE([JEMALLOC_USE_CXX_THROW], [ ])
default_munmap="0"
@@ -418,11 +411,9 @@
[abi="elf"],
[abi="aout"])
AC_MSG_RESULT([$abi])
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
;;
*-*-solaris2*)
abi="elf"
- AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
RPATH='-Wl,-R,$(1)'
dnl Solaris needs this for sigwait().
CPPFLAGS="$CPPFLAGS -D_POSIX_PTHREAD_SEMANTICS"
@@ -1580,12 +1571,33 @@
JE_COMPILABLE([madvise(2)], [
#include <sys/mman.h>
], [
- {
- madvise((void *)0, 0, 0);
- }
+ madvise((void *)0, 0, 0);
], [je_cv_madvise])
if test "x${je_cv_madvise}" = "xyes" ; then
- AC_DEFINE([JEMALLOC_HAVE_MADVISE], [ ])
+ dnl Check for madvise(..., MADV_FREE).
+ JE_COMPILABLE([madvise(..., MADV_FREE)], [
+#include <sys/mman.h>
+], [
+ madvise((void *)0, 0, MADV_FREE);
+], [je_cv_madv_free])
+ if test "x${je_cv_madv_free}" = "xyes" ; then
+ AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
+ fi
+
+ dnl Check for madvise(..., MADV_DONTNEED).
+ JE_COMPILABLE([madvise(..., MADV_DONTNEED)], [
+#include <sys/mman.h>
+], [
+ madvise((void *)0, 0, MADV_DONTNEED);
+], [je_cv_madv_dontneed])
+ if test "x${je_cv_madv_dontneed}" = "xyes" ; then
+ AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED], [ ])
+ fi
+
+ if test "x${je_cv_madv_free}" = "xyes" \
+ -o "x${je_cv_madv_dontneed}" = "xyes" ; then
+ AC_DEFINE([JEMALLOC_HAVE_MADVISE], [ ])
+ fi
fi
dnl ============================================================================
diff --git a/include/jemalloc/internal/jemalloc_internal_defs.h.in b/include/jemalloc/internal/jemalloc_internal_defs.h.in
index 4d2daea..baf12d4 100644
--- a/include/jemalloc/internal/jemalloc_internal_defs.h.in
+++ b/include/jemalloc/internal/jemalloc_internal_defs.h.in
@@ -56,11 +56,6 @@
#undef JEMALLOC_HAVE_BUILTIN_CLZ
/*
- * Defined if madvise(2) is available.
- */
-#undef JEMALLOC_HAVE_MADVISE
-
-/*
* Defined if os_unfair_lock_*() functions are available, as provided by Darwin.
*/
#undef JEMALLOC_OS_UNFAIR_LOCK
@@ -249,18 +244,20 @@
#undef JEMALLOC_SYSCTL_VM_OVERCOMMIT
#undef JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY
+/* Defined if madvise(2) is available. */
+#undef JEMALLOC_HAVE_MADVISE
+
/*
* Methods for purging unused pages differ between operating systems.
*
- * madvise(..., MADV_DONTNEED) : On Linux, this immediately discards pages,
- * such that new pages will be demand-zeroed if
- * the address region is later touched.
- * madvise(..., MADV_FREE) : On FreeBSD and Darwin, this marks pages as being
- * unused, such that they will be discarded rather
- * than swapped out.
+ * madvise(..., MADV_FREE) : This marks pages as being unused, such that they
+ * will be discarded rather than swapped out.
+ * madvise(..., MADV_DONTNEED) : This immediately discards pages, such that
+ * new pages will be demand-zeroed if the
+ * address region is later touched.
*/
-#undef JEMALLOC_PURGE_MADVISE_DONTNEED
#undef JEMALLOC_PURGE_MADVISE_FREE
+#undef JEMALLOC_PURGE_MADVISE_DONTNEED
/* Define if operating system has alloca.h header. */
#undef JEMALLOC_HAS_ALLOCA_H
diff --git a/src/pages.c b/src/pages.c
index 647952a..395ace9 100644
--- a/src/pages.c
+++ b/src/pages.c
@@ -171,14 +171,14 @@
VirtualAlloc(addr, size, MEM_RESET, PAGE_READWRITE);
unzeroed = true;
#elif defined(JEMALLOC_HAVE_MADVISE)
-# ifdef JEMALLOC_PURGE_MADVISE_DONTNEED
-# define JEMALLOC_MADV_PURGE MADV_DONTNEED
-# define JEMALLOC_MADV_ZEROS true
-# elif defined(JEMALLOC_PURGE_MADVISE_FREE)
+# if defined(JEMALLOC_PURGE_MADVISE_FREE)
# define JEMALLOC_MADV_PURGE MADV_FREE
# define JEMALLOC_MADV_ZEROS false
+# elif defined(JEMALLOC_PURGE_MADVISE_DONTNEED)
+# define JEMALLOC_MADV_PURGE MADV_DONTNEED
+# define JEMALLOC_MADV_ZEROS true
# else
-# error "No madvise(2) flag defined for purging unused dirty pages."
+# error No madvise(2) flag defined for purging unused dirty pages
# endif
int err = madvise(addr, size, JEMALLOC_MADV_PURGE);
unzeroed = (!JEMALLOC_MADV_ZEROS || err != 0);
