void*
mono_gc_alloc_obj (MonoVTable *vtable, size_t size)
{
void *res;
SgenThreadInfo *__thread_info__;
if (!SGEN_CAN_ALIGN_UP (size))
return NULL;
#ifndef DISABLE_CRITICAL_REGION
TLAB_ACCESS_INIT;
if (G_UNLIKELY (has_per_allocation_action)) {
static int alloc_count;
int current_alloc = InterlockedIncrement (&alloc_count);
if (verify_before_allocs) {
if ((current_alloc % verify_before_allocs) == 0)
sgen_check_whole_heap_stw ();
}
if (collect_before_allocs) {
if (((current_alloc % collect_before_allocs) == 0) && nursery_section) {
LOCK_GC;
sgen_perform_collection (0, GENERATION_NURSERY, "collect-before-alloc-triggered", TRUE);
UNLOCK_GC;
}
}
}
ENTER_CRITICAL_REGION;
res = mono_gc_try_alloc_obj_nolock (vtable, size);
if (res) {
EXIT_CRITICAL_REGION;
return res;
}
EXIT_CRITICAL_REGION;
#endif
LOCK_GC;
res = mono_gc_alloc_obj_nolock (vtable, size);
UNLOCK_GC;
if (G_UNLIKELY (!res))
return mono_gc_out_of_memory (size);
return res;
}
GCObject*
sgen_alloc_obj (GCVTable vtable, size_t size)
{
GCObject *res;
TLAB_ACCESS_INIT;
if (!SGEN_CAN_ALIGN_UP (size))
return NULL;
if (G_UNLIKELY (sgen_has_per_allocation_action)) {
static int alloc_count;
int current_alloc = mono_atomic_inc_i32 (&alloc_count);
if (sgen_verify_before_allocs) {
if ((current_alloc % sgen_verify_before_allocs) == 0) {
LOCK_GC;
sgen_check_whole_heap_stw ();
UNLOCK_GC;
}
}
if (sgen_collect_before_allocs) {
if (((current_alloc % sgen_collect_before_allocs) == 0) && sgen_nursery_section) {
LOCK_GC;
sgen_perform_collection (0, GENERATION_NURSERY, "collect-before-alloc-triggered", TRUE, TRUE);
UNLOCK_GC;
}
}
}
ENTER_CRITICAL_REGION;
res = sgen_try_alloc_obj_nolock (vtable, size);
if (res) {
EXIT_CRITICAL_REGION;
return res;
}
EXIT_CRITICAL_REGION;
LOCK_GC;
res = sgen_alloc_obj_nolock (vtable, size);
UNLOCK_GC;
return res;
}
static GCObject*
alloc_degraded (GCVTable vtable, size_t size, gboolean for_mature)
{
GCObject *p;
if (!for_mature) {
sgen_client_degraded_allocation ();
SGEN_ATOMIC_ADD_P (sgen_degraded_mode, size);
sgen_ensure_free_space (size, GENERATION_OLD);
} else {
if (sgen_need_major_collection (size))
sgen_perform_collection (size, GENERATION_OLD, "mature allocation failure", !for_mature, TRUE);
}
p = sgen_major_collector.alloc_degraded (vtable, size);
if (!for_mature)
sgen_binary_protocol_alloc_degraded (p, vtable, size, sgen_client_get_provenance ());
return p;
}
static void*
alloc_degraded (MonoVTable *vtable, size_t size, gboolean for_mature)
{
static int last_major_gc_warned = -1;
static int num_degraded = 0;
void *p;
if (!for_mature) {
if (last_major_gc_warned < stat_major_gcs) {
++num_degraded;
if (num_degraded == 1 || num_degraded == 3)
mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "Warning: Degraded allocation. Consider increasing nursery-size if the warning persists.");
else if (num_degraded == 10)
mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "Warning: Repeated degraded allocation. Consider increasing nursery-size.");
last_major_gc_warned = stat_major_gcs;
}
SGEN_ATOMIC_ADD_P (degraded_mode, size);
sgen_ensure_free_space (size);
} else {
if (sgen_need_major_collection (size))
sgen_perform_collection (size, GENERATION_OLD, "mature allocation failure", !for_mature);
}
p = major_collector.alloc_degraded (vtable, size);
if (for_mature) {
MONO_GC_MAJOR_OBJ_ALLOC_MATURE ((mword)p, size, vtable->klass->name_space, vtable->klass->name);
} else {
binary_protocol_alloc_degraded (p, vtable, size);
MONO_GC_MAJOR_OBJ_ALLOC_DEGRADED ((mword)p, size, vtable->klass->name_space, vtable->klass->name);
}
return p;
}
/*
* Provide a variant that takes just the vtable for small fixed-size objects.
* The aligned size is already computed and stored in vt->gc_descr.
* Note: every SGEN_SCAN_START_SIZE or so we are given the chance to do some special
* processing. We can keep track of where objects start, for example,
* so when we scan the thread stacks for pinned objects, we can start
* a search for the pinned object in SGEN_SCAN_START_SIZE chunks.
*/
static void*
mono_gc_alloc_obj_nolock (MonoVTable *vtable, size_t size)
{
/* FIXME: handle OOM */
void **p;
char *new_next;
TLAB_ACCESS_INIT;
HEAVY_STAT (++stat_objects_alloced);
if (size <= SGEN_MAX_SMALL_OBJ_SIZE)
HEAVY_STAT (stat_bytes_alloced += size);
else
HEAVY_STAT (stat_bytes_alloced_los += size);
size = ALIGN_UP (size);
g_assert (vtable->gc_descr);
if (G_UNLIKELY (has_per_allocation_action)) {
static int alloc_count;
int current_alloc = InterlockedIncrement (&alloc_count);
if (collect_before_allocs) {
if (((current_alloc % collect_before_allocs) == 0) && nursery_section) {
sgen_perform_collection (0, GENERATION_NURSERY, "collect-before-alloc-triggered");
if (!degraded_mode && sgen_can_alloc_size (size) && size <= SGEN_MAX_SMALL_OBJ_SIZE) {
// FIXME:
g_assert_not_reached ();
}
}
} else if (verify_before_allocs) {
if ((current_alloc % verify_before_allocs) == 0)
sgen_check_whole_heap_stw ();
}
}
/*
* We must already have the lock here instead of after the
* fast path because we might be interrupted in the fast path
* (after confirming that new_next < TLAB_TEMP_END) by the GC,
* and we'll end up allocating an object in a fragment which
* no longer belongs to us.
*
* The managed allocator does not do this, but it's treated
* specially by the world-stopping code.
*/
if (size > SGEN_MAX_SMALL_OBJ_SIZE) {
p = sgen_los_alloc_large_inner (vtable, size);
} else {
/* tlab_next and tlab_temp_end are TLS vars so accessing them might be expensive */
p = (void**)TLAB_NEXT;
/* FIXME: handle overflow */
new_next = (char*)p + size;
TLAB_NEXT = new_next;
if (G_LIKELY (new_next < TLAB_TEMP_END)) {
/* Fast path */
/*
* FIXME: We might need a memory barrier here so the change to tlab_next is
* visible before the vtable store.
*/
DEBUG (6, fprintf (gc_debug_file, "Allocated object %p, vtable: %p (%s), size: %zd\n", p, vtable, vtable->klass->name, size));
binary_protocol_alloc (p , vtable, size);
if (G_UNLIKELY (MONO_GC_NURSERY_OBJ_ALLOC_ENABLED ()))
MONO_GC_NURSERY_OBJ_ALLOC ((mword)p, size, vtable->klass->name_space, vtable->klass->name);
g_assert (*p == NULL);
mono_atomic_store_seq (p, vtable);
return p;
}
/* Slow path */
/* there are two cases: the object is too big or we run out of space in the TLAB */
/* we also reach here when the thread does its first allocation after a minor
* collection, since the tlab_ variables are initialized to NULL.
* there can be another case (from ORP), if we cooperate with the runtime a bit:
* objects that need finalizers can have the high bit set in their size
* so the above check fails and we can readily add the object to the queue.
* This avoids taking again the GC lock when registering, but this is moot when
* doing thread-local allocation, so it may not be a good idea.
*/
if (TLAB_NEXT >= TLAB_REAL_END) {
int available_in_tlab;
/*
* Run out of space in the TLAB. When this happens, some amount of space
* remains in the TLAB, but not enough to satisfy the current allocation
* request. Currently, we retire the TLAB in all cases, later we could
* keep it if the remaining space is above a treshold, and satisfy the
* allocation directly from the nursery.
*/
TLAB_NEXT -= size;
/* when running in degraded mode, we continue allocing that way
* for a while, to decrease the number of useless nursery collections.
*/
if (degraded_mode && degraded_mode < DEFAULT_NURSERY_SIZE)
return alloc_degraded (vtable, size, FALSE);
available_in_tlab = TLAB_REAL_END - TLAB_NEXT;
if (size > tlab_size || available_in_tlab > SGEN_MAX_NURSERY_WASTE) {
/* Allocate directly from the nursery */
do {
p = sgen_nursery_alloc (size);
if (!p) {
sgen_ensure_free_space (size);
if (degraded_mode)
return alloc_degraded (vtable, size, FALSE);
else
p = sgen_nursery_alloc (size);
}
} while (!p);
if (!p) {
// no space left
g_assert (0);
}
if (nursery_clear_policy == CLEAR_AT_TLAB_CREATION) {
memset (p, 0, size);
}
} else {
size_t alloc_size = 0;
if (TLAB_START)
DEBUG (3, fprintf (gc_debug_file, "Retire TLAB: %p-%p [%ld]\n", TLAB_START, TLAB_REAL_END, (long)(TLAB_REAL_END - TLAB_NEXT - size)));
sgen_nursery_retire_region (p, available_in_tlab);
do {
p = sgen_nursery_alloc_range (tlab_size, size, &alloc_size);
if (!p) {
sgen_ensure_free_space (tlab_size);
if (degraded_mode)
return alloc_degraded (vtable, size, FALSE);
else
p = sgen_nursery_alloc_range (tlab_size, size, &alloc_size);
}
} while (!p);
if (!p) {
// no space left
g_assert (0);
}
/* Allocate a new TLAB from the current nursery fragment */
TLAB_START = (char*)p;
TLAB_NEXT = TLAB_START;
TLAB_REAL_END = TLAB_START + alloc_size;
TLAB_TEMP_END = TLAB_START + MIN (SGEN_SCAN_START_SIZE, alloc_size);
if (nursery_clear_policy == CLEAR_AT_TLAB_CREATION) {
memset (TLAB_START, 0, alloc_size);
}
/* Allocate from the TLAB */
p = (void*)TLAB_NEXT;
TLAB_NEXT += size;
sgen_set_nursery_scan_start ((char*)p);
}
} else {
/* Reached tlab_temp_end */
/* record the scan start so we can find pinned objects more easily */
sgen_set_nursery_scan_start ((char*)p);
/* we just bump tlab_temp_end as well */
TLAB_TEMP_END = MIN (TLAB_REAL_END, TLAB_NEXT + SGEN_SCAN_START_SIZE);
DEBUG (5, fprintf (gc_debug_file, "Expanding local alloc: %p-%p\n", TLAB_NEXT, TLAB_TEMP_END));
}
}
if (G_LIKELY (p)) {
DEBUG (6, fprintf (gc_debug_file, "Allocated object %p, vtable: %p (%s), size: %zd\n", p, vtable, vtable->klass->name, size));
binary_protocol_alloc (p, vtable, size);
if (G_UNLIKELY (MONO_GC_MAJOR_OBJ_ALLOC_LARGE_ENABLED ()|| MONO_GC_NURSERY_OBJ_ALLOC_ENABLED ())) {
if (size > SGEN_MAX_SMALL_OBJ_SIZE)
MONO_GC_MAJOR_OBJ_ALLOC_LARGE ((mword)p, size, vtable->klass->name_space, vtable->klass->name);
else
MONO_GC_NURSERY_OBJ_ALLOC ((mword)p, size, vtable->klass->name_space, vtable->klass->name);
}
mono_atomic_store_seq (p, vtable);
}
return p;
}
/*
* Provide a variant that takes just the vtable for small fixed-size objects.
* The aligned size is already computed and stored in vt->gc_descr.
* Note: every SGEN_SCAN_START_SIZE or so we are given the chance to do some special
* processing. We can keep track of where objects start, for example,
* so when we scan the thread stacks for pinned objects, we can start
* a search for the pinned object in SGEN_SCAN_START_SIZE chunks.
*/
GCObject*
sgen_alloc_obj_nolock (GCVTable vtable, size_t size)
{
/* FIXME: handle OOM */
void **p;
char *new_next;
size_t real_size = size;
TLAB_ACCESS_INIT;
CANARIFY_SIZE(size);
HEAVY_STAT (++stat_objects_alloced);
if (real_size <= SGEN_MAX_SMALL_OBJ_SIZE)
HEAVY_STAT (stat_bytes_alloced += size);
else
HEAVY_STAT (stat_bytes_alloced_los += size);
size = ALIGN_UP (size);
SGEN_ASSERT (6, sgen_vtable_get_descriptor (vtable), "VTable without descriptor");
if (G_UNLIKELY (sgen_has_per_allocation_action)) {
static int alloc_count;
int current_alloc = mono_atomic_inc_i32 (&alloc_count);
if (sgen_collect_before_allocs) {
if (((current_alloc % sgen_collect_before_allocs) == 0) && sgen_nursery_section) {
sgen_perform_collection (0, GENERATION_NURSERY, "collect-before-alloc-triggered", TRUE, TRUE);
if (!sgen_degraded_mode && sgen_can_alloc_size (size) && real_size <= SGEN_MAX_SMALL_OBJ_SIZE) {
// FIXME:
g_assert_not_reached ();
}
}
} else if (sgen_verify_before_allocs) {
if ((current_alloc % sgen_verify_before_allocs) == 0)
sgen_check_whole_heap_stw ();
}
}
/*
* We must already have the lock here instead of after the
* fast path because we might be interrupted in the fast path
* (after confirming that new_next < TLAB_TEMP_END) by the GC,
* and we'll end up allocating an object in a fragment which
* no longer belongs to us.
*
* The managed allocator does not do this, but it's treated
* specially by the world-stopping code.
*/
if (real_size > SGEN_MAX_SMALL_OBJ_SIZE) {
p = (void **)sgen_los_alloc_large_inner (vtable, ALIGN_UP (real_size));
} else {
/* tlab_next and tlab_temp_end are TLS vars so accessing them might be expensive */
p = (void**)TLAB_NEXT;
/* FIXME: handle overflow */
new_next = (char*)p + size;
TLAB_NEXT = new_next;
if (G_LIKELY (new_next < TLAB_TEMP_END)) {
/* Fast path */
CANARIFY_ALLOC(p,real_size);
SGEN_LOG (6, "Allocated object %p, vtable: %p (%s), size: %zd", p, vtable, sgen_client_vtable_get_name (vtable), size);
sgen_binary_protocol_alloc (p , vtable, size, sgen_client_get_provenance ());
g_assert (*p == NULL);
mono_atomic_store_seq (p, vtable);
return (GCObject*)p;
}
/* Slow path */
/* there are two cases: the object is too big or we run out of space in the TLAB */
/* we also reach here when the thread does its first allocation after a minor
* collection, since the tlab_ variables are initialized to NULL.
* there can be another case (from ORP), if we cooperate with the runtime a bit:
* objects that need finalizers can have the high bit set in their size
* so the above check fails and we can readily add the object to the queue.
* This avoids taking again the GC lock when registering, but this is moot when
* doing thread-local allocation, so it may not be a good idea.
*/
if (TLAB_NEXT >= TLAB_REAL_END) {
int available_in_tlab;
/*
* Run out of space in the TLAB. When this happens, some amount of space
* remains in the TLAB, but not enough to satisfy the current allocation
* request. Currently, we retire the TLAB in all cases, later we could
* keep it if the remaining space is above a treshold, and satisfy the
* allocation directly from the nursery.
*/
TLAB_NEXT -= size;
/* when running in degraded mode, we continue allocing that way
* for a while, to decrease the number of useless nursery collections.
*/
if (sgen_degraded_mode && sgen_degraded_mode < sgen_nursery_size)
return alloc_degraded (vtable, size, FALSE);
available_in_tlab = (int)(TLAB_REAL_END - TLAB_NEXT);//We'll never have tlabs > 2Gb
if (size > sgen_tlab_size || available_in_tlab > SGEN_MAX_NURSERY_WASTE) {
/* Allocate directly from the nursery */
p = (void **)sgen_nursery_alloc (size);
if (!p) {
/*
* We couldn't allocate from the nursery, so we try
* collecting. Even after the collection, we might
* still not have enough memory to allocate the
* object. The reason will most likely be that we've
* run out of memory, but there is the theoretical
* possibility that other threads might have consumed
* the freed up memory ahead of us.
*
* What we do in this case is allocate degraded, i.e.,
* from the major heap.
*
* Ideally we'd like to detect the case of other
* threads allocating ahead of us and loop (if we
* always loop we will loop endlessly in the case of
* OOM).
*/
sgen_ensure_free_space (real_size, GENERATION_NURSERY);
if (!sgen_degraded_mode)
p = (void **)sgen_nursery_alloc (size);
}
if (!p)
return alloc_degraded (vtable, size, TRUE);
zero_tlab_if_necessary (p, size);
} else {
size_t alloc_size = 0;
if (TLAB_START)
SGEN_LOG (3, "Retire TLAB: %p-%p [%ld]", TLAB_START, TLAB_REAL_END, (long)(TLAB_REAL_END - TLAB_NEXT - size));
sgen_nursery_retire_region (p, available_in_tlab);
p = (void **)sgen_nursery_alloc_range (sgen_tlab_size, size, &alloc_size);
if (!p) {
/* See comment above in similar case. */
sgen_ensure_free_space (sgen_tlab_size, GENERATION_NURSERY);
if (!sgen_degraded_mode)
p = (void **)sgen_nursery_alloc_range (sgen_tlab_size, size, &alloc_size);
}
if (!p)
return alloc_degraded (vtable, size, TRUE);
/* Allocate a new TLAB from the current nursery fragment */
TLAB_START = (char*)p;
TLAB_NEXT = TLAB_START;
TLAB_REAL_END = TLAB_START + alloc_size;
TLAB_TEMP_END = TLAB_START + MIN (SGEN_SCAN_START_SIZE, alloc_size);
zero_tlab_if_necessary (TLAB_START, alloc_size);
/* Allocate from the TLAB */
p = (void **)TLAB_NEXT;
TLAB_NEXT += size;
sgen_set_nursery_scan_start ((char*)p);
}
} else {
/* Reached tlab_temp_end */
/* record the scan start so we can find pinned objects more easily */
sgen_set_nursery_scan_start ((char*)p);
/* we just bump tlab_temp_end as well */
TLAB_TEMP_END = MIN (TLAB_REAL_END, TLAB_NEXT + SGEN_SCAN_START_SIZE);
SGEN_LOG (5, "Expanding local alloc: %p-%p", TLAB_NEXT, TLAB_TEMP_END);
}
CANARIFY_ALLOC(p,real_size);
}
if (G_LIKELY (p)) {
SGEN_LOG (6, "Allocated object %p, vtable: %p (%s), size: %zd", p, vtable, sgen_client_vtable_get_name (vtable), size);
sgen_binary_protocol_alloc (p, vtable, size, sgen_client_get_provenance ());
mono_atomic_store_seq (p, vtable);
}
return (GCObject*)p;
}
