236 lines
6.3 KiB
Diff
236 lines
6.3 KiB
Diff
Allow M_ARENA_MAX / MALLOC_ARENA_MAX limit even with PER_THREAD disabled
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With the new PER_THREAD compile-time option, the allocator also offers
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a way to limit the total number of arenas using MALLOC_ARENA_MAX
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environment variable or mallopt(M_ARENA_MAX).
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In principle, this feature is not tied to the PER_THREAD option. This
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patch makes it possible to use it even with the default compilation
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settings.
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One motivation to limit the number of arenas may be libhugetlbfs users
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that rely on its __morecore hook providing hugetlbfs-backed memory for
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the allocator - this can work only with a single arena and multi-threaded
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programs wishing to use this feature need a way to limit the allocator
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to a single arena. Another motivation is avoiding pathological behavior
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in extremely thread-intensive applications.
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2011-02-04 Petr Baudis <pasky@suse.cz>
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* malloc/arena.c: Define and manage narenas even ifndef
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PER_THREAD.
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* malloc/arena.c (ptmalloc_init_minimal): Likewise.
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* malloc/arena.c (_int_new_arena): Likewise.
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* malloc/arena.c (ptmalloc_init): Implement MALLOC_ARENA_MAX
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even ifndef PER_THREAD.
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* malloc/arena.c (reused_arena): Split off get_narenas_limit(),
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define even ifndef PER_THREAD.
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* malloc/arena.c (arena_get2): Adjust for get_narenas_limit()
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split, call reused_arena even ifndef PER_THREAD.
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* malloc/hooks.c (public_gET_STATe): Set arena_max, narenas
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even ifndef PER_THREAD.
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* malloc/hooks.c (public_sET_STATe): Likewise.
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* malloc/malloc.c (malloc_par): Define arena_max even ifndef
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PER_THREAD.
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* malloc/malloc.c (mALLOPt): Implement M_ARENA_MAX even ifndef
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PER_THREAD.
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* malloc/malloc.c: Remove redundant M_* defines.
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diff --git a/malloc/arena.c b/malloc/arena.c
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index 4d0deef..ea80724 100644
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--- a/malloc/arena.c
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+++ b/malloc/arena.c
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@@ -78,8 +78,8 @@ extern int sanity_check_heap_info_alignment[(sizeof (heap_info)
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static tsd_key_t arena_key;
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static mutex_t list_lock;
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-#ifdef PER_THREAD
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static size_t narenas;
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+#ifdef PER_THREAD
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static mstate free_list;
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#endif
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@@ -416,8 +416,8 @@ ptmalloc_init_minimal (void)
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#ifdef PER_THREAD
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# define NARENAS_FROM_NCORES(n) ((n) * (sizeof(long) == 4 ? 2 : 8))
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mp_.arena_test = NARENAS_FROM_NCORES (1);
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- narenas = 1;
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#endif
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+ narenas = 1;
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}
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@@ -574,10 +574,8 @@ ptmalloc_init (void)
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{
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if (memcmp (envline, "MMAP_MAX_", 9) == 0)
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mALLOPt(M_MMAP_MAX, atoi(&envline[10]));
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-#ifdef PER_THREAD
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else if (memcmp (envline, "ARENA_MAX", 9) == 0)
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mALLOPt(M_ARENA_MAX, atoi(&envline[10]));
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-#endif
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}
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break;
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#ifdef PER_THREAD
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@@ -946,9 +944,9 @@ _int_new_arena(size_t size)
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atomic_write_barrier ();
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main_arena.next = a;
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-#ifdef PER_THREAD
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++narenas;
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+#ifdef PER_THREAD
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(void)mutex_unlock(&list_lock);
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#endif
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@@ -982,13 +980,9 @@ get_free_list (void)
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return result;
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}
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-
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-static mstate
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-reused_arena (void)
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+static int
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+get_narenas_limit (void) __attribute__((pure))
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{
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- if (narenas <= mp_.arena_test)
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- return NULL;
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-
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static int narenas_limit;
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if (narenas_limit == 0)
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{
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@@ -1006,10 +1000,16 @@ reused_arena (void)
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narenas_limit = NARENAS_FROM_NCORES (2);
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}
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}
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+ return narenas_limit;
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+}
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+#endif
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- if (narenas < narenas_limit)
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- return NULL;
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+/* Reuse and return one of the existing arenas; if all arenas are busy,
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+ * pick one in a round-robin fashion and block until it becomes available. */
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+static mstate
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+reused_arena (void)
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+{
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mstate result;
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static mstate next_to_use;
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if (next_to_use == NULL)
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@@ -1035,7 +1035,6 @@ reused_arena (void)
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return result;
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}
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-#endif
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static mstate
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internal_function
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@@ -1048,10 +1047,15 @@ arena_get2(a_tsd, size) mstate a_tsd; size_t size;
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mstate a;
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#ifdef PER_THREAD
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- if ((a = get_free_list ()) == NULL
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- && (a = reused_arena ()) == NULL)
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- /* Nothing immediately available, so generate a new arena. */
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- a = _int_new_arena(size);
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+ if ((a = get_free_list ()) == NULL)
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+ {
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+ if (narenas > mp_.arena_test && narenas >= get_narenas_limit())
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+ a = reused_arena ();
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+ else
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+ /* Nothing immediately available, but we can still generate more
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+ * arenas, so get a new one. */
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+ a = _int_new_arena(size);
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+ }
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#else
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if(!a_tsd)
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a = a_tsd = &main_arena;
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@@ -1093,8 +1097,14 @@ arena_get2(a_tsd, size) mstate a_tsd; size_t size;
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goto repeat;
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}
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- /* Nothing immediately available, so generate a new arena. */
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- a = _int_new_arena(size);
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+ if (__builtin_expect(mp_.arena_max > 0, 0) && narenas >= mp_.arena_max)
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+ /* Try again, this time blocking in case we are still unable to find
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+ * a free arena. */
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+ a = reused_arena();
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+ else
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+ /* Nothing immediately available, so generate a new arena. */
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+ a = _int_new_arena(size);
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+
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(void)mutex_unlock(&list_lock);
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#endif
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diff --git a/malloc/hooks.c b/malloc/hooks.c
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index 28845ee..e938492 100644
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--- a/malloc/hooks.c
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+++ b/malloc/hooks.c
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@@ -579,9 +579,9 @@ public_gET_STATe(void)
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ms->max_fast = get_max_fast();
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#ifdef PER_THREAD
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ms->arena_test = mp_.arena_test;
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+#endif
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ms->arena_max = mp_.arena_max;
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ms->narenas = narenas;
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-#endif
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(void)mutex_unlock(&main_arena.mutex);
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return (Void_t*)ms;
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}
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@@ -683,9 +683,9 @@ public_sET_STATe(Void_t* msptr)
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if (ms->version >= 4) {
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#ifdef PER_THREAD
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mp_.arena_test = ms->arena_test;
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+#endif
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mp_.arena_max = ms->arena_max;
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narenas = ms->narenas;
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-#endif
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}
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check_malloc_state(&main_arena);
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diff --git a/malloc/malloc.c b/malloc/malloc.c
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index b1d43c6..8dbadfa 100644
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--- a/malloc/malloc.c
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+++ b/malloc/malloc.c
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@@ -2406,9 +2406,10 @@ struct malloc_par {
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INTERNAL_SIZE_T top_pad;
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INTERNAL_SIZE_T mmap_threshold;
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#ifdef PER_THREAD
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+ /* Lower bound for arena_max. */
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INTERNAL_SIZE_T arena_test;
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- INTERNAL_SIZE_T arena_max;
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#endif
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+ INTERNAL_SIZE_T arena_max;
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/* Memory map support */
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int n_mmaps;
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@@ -2446,13 +2447,6 @@ static struct malloc_state main_arena;
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static struct malloc_par mp_;
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-#ifdef PER_THREAD
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-/* Non public mallopt parameters. */
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-#define M_ARENA_TEST -7
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-#define M_ARENA_MAX -8
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-#endif
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-
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-
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/* Maximum size of memory handled in fastbins. */
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static INTERNAL_SIZE_T global_max_fast;
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@@ -6095,12 +6089,12 @@ int mALLOPt(param_number, value) int param_number; int value;
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if (value > 0)
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mp_.arena_test = value;
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break;
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+#endif
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case M_ARENA_MAX:
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if (value > 0)
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mp_.arena_max = value;
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break;
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-#endif
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}
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(void)mutex_unlock(&av->mutex);
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return res;
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