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[PATCH] Drop PER_THREAD conditionals.


Hi, when I looked at malloc code I wondered on what conditions 
we compile malloc with PER_THREAD. As in Makefile we have PER_THREAD 
enabled unconditionally. There may be reason to keep a PER_THREAD but
for simplicity of implementation I would just remove it.

Could somebody shed light on this.


	* malloc/Makefile: Remove PER_THREAD flag.
	* malloc/arena.c [PER_THREAD]: Remove conditionals.
	[!PER_THREAD]: Remove enclosed code.
	* malloc/hooks.c [PER_THREAD]: Remove conditionals.
	* malloc/malloc.c [PER_THREAD]: Remove conditionals.
	[!PER_THREAD]: Remove enclosed code.



>From bcc99638e434cdf561118a2bffcced30a7e6f317 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20B=C3=ADlka?= <neleai@seznam.cz>
Date: Fri, 6 Dec 2013 00:41:40 +0100
Subject: [PATCH] Remove PER_THREAD condition

---
 malloc/Makefile |  1 -
 malloc/arena.c  | 76 ---------------------------------------------------------
 malloc/hooks.c  |  4 ---
 malloc/malloc.c | 15 ------------
 4 files changed, 96 deletions(-)

diff --git a/malloc/Makefile b/malloc/Makefile
index 84339d1..0c1e19f 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -119,7 +119,6 @@ endif
 tst-mcheck-ENV = MALLOC_CHECK_=3
 tst-malloc-usable-ENV = MALLOC_CHECK_=3
 
-CPPFLAGS-malloc.c += -DPER_THREAD
 # Uncomment this for test releases.  For public releases it is too expensive.
 #CPPFLAGS-malloc.o += -DMALLOC_DEBUG=1
 
diff --git a/malloc/arena.c b/malloc/arena.c
index d81ed0d..91c44de 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -75,10 +75,8 @@ extern int sanity_check_heap_info_alignment[(sizeof (heap_info)
 
 static tsd_key_t arena_key;
 static mutex_t list_lock = MUTEX_INITIALIZER;
-#ifdef PER_THREAD
 static size_t narenas = 1;
 static mstate free_list;
-#endif
 
 #if THREAD_STATS
 static int stat_n_heaps;
@@ -114,21 +112,12 @@ int __malloc_initialized = -1;
   ptr = (mstate)tsd_getspecific(arena_key, vptr); \
 } while(0)
 
-#ifdef PER_THREAD
 # define arena_lock(ptr, size) do { \
   if(ptr) \
     (void)mutex_lock(&ptr->mutex); \
   else \
     ptr = arena_get2(ptr, (size), NULL); \
 } while(0)
-#else
-# define arena_lock(ptr, size) do { \
-  if(ptr && !mutex_trylock(&ptr->mutex)) { \
-    THREAD_STAT(++(ptr->stat_lock_direct)); \
-  } else \
-    ptr = arena_get2(ptr, (size), NULL); \
-} while(0)
-#endif
 
 /* find the heap and corresponding arena for a given ptr */
 
@@ -292,17 +281,13 @@ ptmalloc_unlock_all2 (void)
   tsd_setspecific(arena_key, save_arena);
   __malloc_hook = save_malloc_hook;
   __free_hook = save_free_hook;
-#ifdef PER_THREAD
   free_list = NULL;
-#endif
   for(ar_ptr = &main_arena;;) {
     mutex_init(&ar_ptr->mutex);
-#ifdef PER_THREAD
     if (ar_ptr != save_arena) {
       ar_ptr->next_free = free_list;
       free_list = ar_ptr;
     }
-#endif
     ar_ptr = ar_ptr->next;
     if(ar_ptr == &main_arena) break;
   }
@@ -423,13 +408,10 @@ ptmalloc_init (void)
 		{
 		  if (memcmp (envline, "MMAP_MAX_", 9) == 0)
 		    __libc_mallopt(M_MMAP_MAX, atoi(&envline[10]));
-#ifdef PER_THREAD
 		  else if (memcmp (envline, "ARENA_MAX", 9) == 0)
 		    __libc_mallopt(M_ARENA_MAX, atoi(&envline[10]));
-#endif
 		}
 	      break;
-#ifdef PER_THREAD
 	    case 10:
 	      if (! __builtin_expect (__libc_enable_secure, 0))
 		{
@@ -437,7 +419,6 @@ ptmalloc_init (void)
 		    __libc_mallopt(M_ARENA_TEST, atoi(&envline[11]));
 		}
 	      break;
-#endif
 	    case 15:
 	      if (! __builtin_expect (__libc_enable_secure, 0))
 		{
@@ -745,18 +726,14 @@ _int_new_arena(size_t size)
   mutex_init(&a->mutex);
   (void)mutex_lock(&a->mutex);
 
-#ifdef PER_THREAD
   (void)mutex_lock(&list_lock);
-#endif
 
   /* Add the new arena to the global list.  */
   a->next = main_arena.next;
   atomic_write_barrier ();
   main_arena.next = a;
 
-#ifdef PER_THREAD
   (void)mutex_unlock(&list_lock);
-#endif
 
   THREAD_STAT(++(a->stat_lock_loop));
 
@@ -764,7 +741,6 @@ _int_new_arena(size_t size)
 }
 
 
-#ifdef PER_THREAD
 static mstate
 get_free_list (void)
 {
@@ -827,7 +803,6 @@ reused_arena (mstate avoid_arena)
 
   return result;
 }
-#endif
 
 static mstate
 internal_function
@@ -835,7 +810,6 @@ arena_get2(mstate a_tsd, size_t size, mstate avoid_arena)
 {
   mstate a;
 
-#ifdef PER_THREAD
   static size_t narenas_limit;
 
   a = get_free_list ();
@@ -878,54 +852,6 @@ arena_get2(mstate a_tsd, size_t size, mstate avoid_arena)
       else
 	a = reused_arena (avoid_arena);
     }
-#else
-  if(!a_tsd)
-    a = a_tsd = &main_arena;
-  else {
-    a = a_tsd->next;
-    if(!a) {
-      /* This can only happen while initializing the new arena. */
-      (void)mutex_lock(&main_arena.mutex);
-      THREAD_STAT(++(main_arena.stat_lock_wait));
-      return &main_arena;
-    }
-  }
-
-  /* Check the global, circularly linked list for available arenas. */
-  bool retried = false;
- repeat:
-  do {
-    if(!mutex_trylock(&a->mutex)) {
-      if (retried)
-	(void)mutex_unlock(&list_lock);
-      THREAD_STAT(++(a->stat_lock_loop));
-      LIBC_PROBE (memory_arena_reuse, 2, a, a_tsd);
-      tsd_setspecific(arena_key, (void *)a);
-      return a;
-    }
-    a = a->next;
-  } while(a != a_tsd);
-
-  /* If not even the list_lock can be obtained, try again.  This can
-     happen during `atfork', or for example on systems where thread
-     creation makes it temporarily impossible to obtain _any_
-     locks. */
-  if(!retried && mutex_trylock(&list_lock)) {
-    /* We will block to not run in a busy loop.  */
-    LIBC_PROBE (memory_arena_reuse_wait, 3, &list_lock, NULL, a_tsd);
-    (void)mutex_lock(&list_lock);
-
-    /* Since we blocked there might be an arena available now.  */
-    retried = true;
-    a = a_tsd;
-    goto repeat;
-  }
-
-  /* Nothing immediately available, so generate a new arena.  */
-  a = _int_new_arena(size);
-  (void)mutex_unlock(&list_lock);
-#endif
-
   return a;
 }
 
@@ -951,7 +877,6 @@ arena_get_retry (mstate ar_ptr, size_t bytes)
   return ar_ptr;
 }
 
-#ifdef PER_THREAD
 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
 arena_thread_freeres (void)
 {
@@ -968,7 +893,6 @@ arena_thread_freeres (void)
     }
 }
 text_set_element (__libc_thread_subfreeres, arena_thread_freeres);
-#endif
 
 /*
  * Local variables:
diff --git a/malloc/hooks.c b/malloc/hooks.c
index 89fbd3c..935da5c 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -476,11 +476,9 @@ __malloc_get_state(void)
   ms->max_mmapped_mem = mp_.max_mmapped_mem;
   ms->using_malloc_checking = using_malloc_checking;
   ms->max_fast = get_max_fast();
-#ifdef PER_THREAD
   ms->arena_test = mp_.arena_test;
   ms->arena_max = mp_.arena_max;
   ms->narenas = narenas;
-#endif
   (void)mutex_unlock(&main_arena.mutex);
   return (void*)ms;
 }
@@ -577,11 +575,9 @@ __malloc_set_state(void* msptr)
     }
   }
   if (ms->version >= 4) {
-#ifdef PER_THREAD
     mp_.arena_test = ms->arena_test;
     mp_.arena_max = ms->arena_max;
     narenas = ms->narenas;
-#endif
   }
   check_malloc_state(&main_arena);
 
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 8977687..4799e7a 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1714,10 +1714,8 @@ struct malloc_state {
   /* Linked list */
   struct malloc_state *next;
 
-#ifdef PER_THREAD
   /* Linked list for free arenas.  */
   struct malloc_state *next_free;
-#endif
 
   /* Memory allocated from the system in this arena.  */
   INTERNAL_SIZE_T system_mem;
@@ -1729,10 +1727,8 @@ struct malloc_par {
   unsigned long    trim_threshold;
   INTERNAL_SIZE_T  top_pad;
   INTERNAL_SIZE_T  mmap_threshold;
-#ifdef PER_THREAD
   INTERNAL_SIZE_T  arena_test;
   INTERNAL_SIZE_T  arena_max;
-#endif
 
   /* Memory map support */
   int              n_mmaps;
@@ -1774,18 +1770,14 @@ static struct malloc_par mp_ =
     .n_mmaps_max    = DEFAULT_MMAP_MAX,
     .mmap_threshold = DEFAULT_MMAP_THRESHOLD,
     .trim_threshold = DEFAULT_TRIM_THRESHOLD,
-#ifdef PER_THREAD
 # define NARENAS_FROM_NCORES(n) ((n) * (sizeof(long) == 4 ? 2 : 8))
     .arena_test     = NARENAS_FROM_NCORES (1)
-#endif
   };
 
 
-#ifdef PER_THREAD
 /*  Non public mallopt parameters.  */
 #define M_ARENA_TEST -7
 #define M_ARENA_MAX  -8
-#endif
 
 
 /* Maximum size of memory handled in fastbins.  */
@@ -2974,11 +2966,6 @@ __libc_realloc(void* oldmem, size_t bytes)
   (void)mutex_lock(&ar_ptr->mutex);
 #endif
 
-#if !defined PER_THREAD
-  LIBC_PROBE (memory_arena_reuse_realloc, 1, ar_ptr);
-  /* As in malloc(), remember this arena for the next allocation. */
-  tsd_setspecific(arena_key, (void *)ar_ptr);
-#endif
 
   newp = _int_realloc(ar_ptr, oldp, oldsize, nb);
 
@@ -4690,7 +4677,6 @@ int __libc_mallopt(int param_number, int value)
     perturb_byte = value;
     break;
 
-#ifdef PER_THREAD
   case M_ARENA_TEST:
     if (value > 0)
       {
@@ -4706,7 +4692,6 @@ int __libc_mallopt(int param_number, int value)
 	mp_.arena_max = value;
       }
     break;
-#endif
   }
   (void)mutex_unlock(&av->mutex);
   return res;
-- 
1.8.4.rc3


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