X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/aa022d1e577ba93e5fb2841a312b8ac6b00a4ffd..4eb9402362d5ecd76b79b1054ba37a8de264a280:/src/xbt/mallocator.c diff --git a/src/xbt/mallocator.c b/src/xbt/mallocator.c index 5a4f2fcb38..3acc9b3123 100644 --- a/src/xbt/mallocator.c +++ b/src/xbt/mallocator.c @@ -14,12 +14,79 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_mallocator, xbt, "Mallocators"); -/* Mallocators and memory mess introduced by model-checking do not mix well +/** Implementation note on the mallocators: + * + * Mallocators and memory mess introduced by model-checking do not mix well * together: the mallocator will give standard memory when we are using raw * memory (so these blocks are killed on restore) and the contrary (so these - * blocks will leak accross restores). + * blocks will leak across restores). + * + * In addition, model-checking is activated when the command-line arguments + * are parsed, at the beginning of main, while most of the mallocators are + * created during the constructor functions launched from xbt_preinit, before + * the beginning of the main function. + * + * We want the code as fast as possible when they are active while we can deal + * with a little slow-down when they are inactive. So we start the mallocators + * as inactive. When they are so, they check at each use whether they should + * switch to the fast active mode or should stay in inactive mode. + * Finally, we give external elements a way to switch them + * all to the active mode (through xbt_mallocator_initialization_is_done). + * + * This design avoids to store all mallocators somewhere for later conversion, + * which would be hard to achieve provided that all our data structures use + * some mallocators internally... */ -#define MALLOCATOR_IS_ENABLED (MALLOCATOR_IS_WANTED && !MC_is_active()) + +/* Value != 0 when the framework configuration is done. Value > 1 if the + * mallocators should be protected from concurrent accesses. */ +static int initialization_done = 0; + +static XBT_INLINE void lock_create(xbt_mallocator_t m) +{ + m->lock = 0; +} + +static XBT_INLINE void lock_destroy(xbt_mallocator_t m) +{ +} + +static XBT_INLINE void lock_acquire(xbt_mallocator_t m) +{ + if (initialization_done > 1) { + int *lock = &m->lock; + while (__sync_lock_test_and_set(lock, 1)) + /* nop */; + } +} + +static XBT_INLINE void lock_release(xbt_mallocator_t m) +{ + if (initialization_done > 1) + __sync_lock_release(&m->lock); +} + +/** + * This function must be called once the framework configuration is done. If not, + * mallocators will never get used. Check the implementation notes in + * src/xbt/mallocator.c for the justification of this. + * + * For example, surf_config uses this function to tell to the mallocators that + * the simgrid + * configuration is now finished and that it can create them if not done yet */ +void xbt_mallocator_initialization_is_done(int protect) +{ + initialization_done = protect ? 2 : 1; +} + +/** used by the module to know if it's time to activate the mallocators yet */ +static XBT_INLINE int xbt_mallocator_is_active(void) { +#if MALLOCATOR_COMPILED_IN + return initialization_done && !MC_is_active(); +#else + return 0; +#endif +} /** * \brief Constructor @@ -50,21 +117,13 @@ xbt_mallocator_t xbt_mallocator_new(int size, m = xbt_new0(s_xbt_mallocator_t, 1); XBT_VERB("Create mallocator %p (%s)", - m, MALLOCATOR_IS_ENABLED ? "enabled" : "disabled"); + m, xbt_mallocator_is_active() ? "enabled" : "disabled"); m->current_size = 0; m->new_f = new_f; m->free_f = free_f; m->reset_f = reset_f; + m->max_size = size; - if (MALLOCATOR_IS_ENABLED) { - m->objects = xbt_new0(void *, size); - m->max_size = size; - m->mutex = xbt_os_mutex_init(); - } else { - m->objects = NULL; - m->max_size = 0; - m->mutex = NULL; - } return m; } @@ -88,7 +147,7 @@ void xbt_mallocator_free(xbt_mallocator_t m) m->free_f(m->objects[i]); } xbt_free(m->objects); - xbt_os_mutex_destroy(m->mutex); + lock_destroy(m); xbt_free(m); } @@ -112,8 +171,8 @@ void *xbt_mallocator_get(xbt_mallocator_t m) { void *object; - if (MALLOCATOR_IS_ENABLED) { - xbt_os_mutex_acquire(m->mutex); + if (m->objects != NULL) { // this mallocator is active, stop thinking and go for it! + lock_acquire(m); if (m->current_size <= 0) { /* No object is ready yet. Create a bunch of them to try to group the * mallocs on the same memory pages (to help the cache lines) */ @@ -131,9 +190,16 @@ void *xbt_mallocator_get(xbt_mallocator_t m) /* XBT_DEBUG("Reuse an old object for mallocator %p (size:%d/%d)", */ /* m, m->current_size, m->max_size); */ object = m->objects[--m->current_size]; - xbt_os_mutex_release(m->mutex); + lock_release(m); } else { - object = m->new_f(); + if (xbt_mallocator_is_active()) { + // We have to switch this mallocator from inactive to active (and then get an object) + m->objects = xbt_new0(void *, m->max_size); + lock_create(m); + return xbt_mallocator_get(m); + } else { + object = m->new_f(); + } } if (m->reset_f) @@ -156,23 +222,30 @@ void *xbt_mallocator_get(xbt_mallocator_t m) */ void xbt_mallocator_release(xbt_mallocator_t m, void *object) { - if (MALLOCATOR_IS_ENABLED) { - xbt_os_mutex_acquire(m->mutex); + if (m->objects != NULL) { // Go for it + lock_acquire(m); if (m->current_size < m->max_size) { /* there is enough place to push the object */ /* XBT_DEBUG ("Store deleted object in mallocator %p for further use (size:%d/%d)", m, m->current_size, m->max_size); */ m->objects[m->current_size++] = object; - xbt_os_mutex_release(m->mutex); + lock_release(m); } else { - xbt_os_mutex_release(m->mutex); + lock_release(m); /* otherwise we don't have a choice, we must free the object */ /* XBT_DEBUG("Free deleted object: mallocator %p is full (size:%d/%d)", m, m->current_size, m->max_size); */ m->free_f(object); } } else { - m->free_f(object); + if (xbt_mallocator_is_active()) { + // We have to switch this mallocator from inactive to active (and then store that object) + m->objects = xbt_new0(void *, m->max_size); + lock_create(m); + xbt_mallocator_release(m,object); + } else { + m->free_f(object); + } } }