[git commit master] experimentally add mallopt tweaks for reduced memory consumption

[Denys Vlasenko]

commit: http://git.busybox.net/busybox/commit/?id=1f7c167b23dfd5b03f386a657cb95867e1605e1b
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
mallopt                                                -     126    +126
main                                                  91     117     +26
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/0 up/down: 152/0)             Total: 152 bytes

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 libbb/appletlib.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 814b8bc..0ebea4f 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -28,6 +28,8 @@
  */
 
 #include <assert.h>
+#include <malloc.h>
+#include <sys/user.h> /* PAGE_SIZE */
 #include "busybox.h"
 
 
@@ -763,6 +765,24 @@ int lbb_main(char **argv)
 int main(int argc UNUSED_PARAM, char **argv)
 #endif
 {
+	/* Tweak malloc for reduced memory consumption */
+#ifndef PAGE_SIZE
+# define PAGE_SIZE (4*1024) /* guess */
+#endif
+#ifdef M_TRIM_THRESHOLD
+	/* M_TRIM_THRESHOLD is the maximum amount of freed top-most memory
+	 * to keep before releasing to the OS
+	 * Default is way too big: 256k
+	 */
+	mallopt(M_TRIM_THRESHOLD, 2 * PAGE_SIZE);
+#endif
+#ifdef M_MMAP_THRESHOLD
+	/* M_MMAP_THRESHOLD is the request size threshold for using mmap()
+	 * Default is too big: 256k
+	 */
+	mallopt(M_MMAP_THRESHOLD, 8 * PAGE_SIZE - 256);
+#endif
+
 #if defined(SINGLE_APPLET_MAIN)
 	/* Only one applet is selected by the user! */
 	/* applet_names in this case is just "applet\0\0" */
-- 
1.6.3.3