Add glibc.malloc.mxfast tunable

* elf/dl-tunables.list: Add glibc.malloc.mxfast.
* manual/tunables.texi: Document it.
* malloc/malloc.c (do_set_mxfast): New.
(__libc_mallopt): Call it.
* malloc/arena.c: Add mxfast tunable.
* malloc/tst-mxfast.c: New.
* malloc/Makefile: Add it.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit c48d92b430c480de06762f80c104922239416826)

1 files changed, 14 insertions, 7 deletions

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 22f1049056..23dd6054c5 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5140,6 +5140,19 @@ do_set_tcache_unsorted_limit (size_t value)
 }
 #endif
 
+static inline int
+__always_inline
+do_set_mxfast (size_t value)
+{
+  if (value >= 0 && value <= MAX_FAST_SIZE)
+    {
+      LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
+      set_max_fast (value);
+      return 1;
+    }
+  return 0;
+}
+
 int
 __libc_mallopt (int param_number, int value)
 {
@@ -5159,13 +5172,7 @@ __libc_mallopt (int param_number, int value)
   switch (param_number)
     {
     case M_MXFAST:
-      if (value >= 0 && value <= MAX_FAST_SIZE)
-        {
-          LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
-          set_max_fast (value);
-        }
-      else
-        res = 0;
+      do_set_mxfast (value);
       break;
 
     case M_TRIM_THRESHOLD: