glibc/glibc-rh740506.patch

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* malloc/arena.c (arena_get2): Avoid unnecessarily
retrieving #cpus from /proc.
* malloc/malloc.c (mALLOPt): Clamp arena_test based on
the value of arena_max.
commit 41b81892f11fe1353123e892158b53de73863d62
Author: Ulrich Drepper <drepper@gmail.com>
Date: Tue Jan 31 14:42:34 2012 -0500
Handle ARENA_TEST correctly
diff --git a/malloc/arena.c b/malloc/arena.c
index d3cf4b9..b1c9469 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -828,7 +828,7 @@ arena_get2(mstate a_tsd, size_t size)
{
if (mp_.arena_max != 0)
narenas_limit = mp_.arena_max;
- else
+ else if (narenas > mp_.arena_test)
{
int n = __get_nprocs ();
@@ -842,7 +842,14 @@ arena_get2(mstate a_tsd, size_t size)
}
repeat:;
size_t n = narenas;
- if (__builtin_expect (n <= mp_.arena_test || n < narenas_limit, 0))
+ /* NB: the following depends on the fact that (size_t)0 - 1 is a
+ very large number and that the underflow is OK. If arena_max
+ is set the value of arena_test is irrelevant. If arena_test
+ is set but narenas is not yet larger or equal to arena_test
+ narenas_limit is 0. There is no possibility for narenas to
+ be too big for the test to always fail since there is not
+ enough address space to create that many arenas. */
+ if (__builtin_expect (n <= narenas_limit - 1, 0))
{
if (catomic_compare_and_exchange_bool_acq (&narenas, n + 1, n))
goto repeat;