static void collector_trace_rootsets(Collector* collector)
{
GC* gc = collector->gc;
GC_Metadata* metadata = gc->metadata;
#ifdef GC_GEN_STATS
GC_Gen_Collector_Stats* stats = (GC_Gen_Collector_Stats*)collector->stats;
#endif
unsigned int num_active_collectors = gc->num_active_collectors;
atomic_cas32( &num_finished_collectors, 0, num_active_collectors);
Space* space = collector->collect_space;
collector->trace_stack = free_task_pool_get_entry(metadata);
/* find root slots saved by 1. active mutators, 2. exited mutators, 3. last cycle collectors */
Vector_Block* root_set = pool_iterator_next(metadata->gc_rootset_pool);
/* first step: copy all root objects to trace tasks. */
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: copy root objects to trace stack ...");
while(root_set){
POINTER_SIZE_INT* iter = vector_block_iterator_init(root_set);
while(!vector_block_iterator_end(root_set,iter)){
REF *p_ref = (REF *)*iter;
iter = vector_block_iterator_advance(root_set, iter);
assert(*p_ref); /* root ref cann't be NULL, but remset can be */
collector_tracestack_push(collector, p_ref);
#ifdef GC_GEN_STATS
gc_gen_collector_update_rootset_ref_num(stats);
#endif
}
root_set = pool_iterator_next(metadata->gc_rootset_pool);
}
/* put back the last trace_stack task */
pool_put_entry(metadata->mark_task_pool, collector->trace_stack);
/* second step: iterate over the trace tasks and forward objects */
collector->trace_stack = free_task_pool_get_entry(metadata);
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: finish copying root objects to trace stack.");
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: trace and forward objects ...");
retry:
Vector_Block* trace_task = pool_get_entry(metadata->mark_task_pool);
while(trace_task){
POINTER_SIZE_INT* iter = vector_block_iterator_init(trace_task);
while(!vector_block_iterator_end(trace_task,iter)){
REF *p_ref = (REF *)*iter;
iter = vector_block_iterator_advance(trace_task, iter);
#ifdef PREFETCH_SUPPORTED
/* DO PREFETCH */
if( mark_prefetch ) {
if(!vector_block_iterator_end(trace_task, iter)) {
REF *pref= (REF*) *iter;
PREFETCH( read_slot(pref));
}
}
#endif
trace_object(collector, p_ref);
if(collector->result == FALSE) break; /* force return */
}
vector_stack_clear(trace_task);
pool_put_entry(metadata->free_task_pool, trace_task);
if(collector->result == FALSE){
gc_task_pool_clear(metadata->mark_task_pool);
break; /* force return */
}
trace_task = pool_get_entry(metadata->mark_task_pool);
}
/* A collector comes here when seeing an empty mark_task_pool. The last collector will ensure
all the tasks are finished.*/
atomic_inc32(&num_finished_collectors);
while(num_finished_collectors != num_active_collectors){
if( pool_is_empty(metadata->mark_task_pool)) continue;
/* we can't grab the task here, because of a race condition. If we grab the task,
and the pool is empty, other threads may fall to this barrier and then pass. */
atomic_dec32(&num_finished_collectors);
goto retry;
}
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: finish tracing and forwarding objects.");
/* now we are done, but each collector has a private stack that is empty */
trace_task = (Vector_Block*)collector->trace_stack;
vector_stack_clear(trace_task);
pool_put_entry(metadata->free_task_pool, trace_task);
collector->trace_stack = NULL;
return;
}
void mark_scan_pool(Collector* collector)
{
GC* gc = collector->gc;
GC_Metadata* metadata = gc->metadata;
#ifdef GC_GEN_STATS
GC_Gen_Collector_Stats* stats = (GC_Gen_Collector_Stats*)collector->stats;
#endif
/* reset the num_finished_collectors to be 0 by one collector. This is necessary for the barrier later. */
unsigned int num_active_collectors = gc->num_active_collectors;
atomic_cas32( &num_finished_collectors, 0, num_active_collectors);
collector->trace_stack = free_task_pool_get_entry(metadata);
Vector_Block* root_set = pool_iterator_next(metadata->gc_rootset_pool);
/* first step: copy all root objects to mark tasks.
FIXME:: can be done sequentially before coming here to eliminate atomic ops */
while(root_set){
POINTER_SIZE_INT* iter = vector_block_iterator_init(root_set);
while(!vector_block_iterator_end(root_set,iter)){
REF *p_ref = (REF *)*iter;
iter = vector_block_iterator_advance(root_set,iter);
Partial_Reveal_Object *p_obj = read_slot(p_ref);
/* root ref can't be NULL, (remset may have NULL ref entry, but this function is only for ALGO_MAJOR */
assert(p_obj!=NULL);
/* we have to mark the object before put it into marktask, because
it is possible to have two slots containing a same object. They will
be scanned twice and their ref slots will be recorded twice. Problem
occurs after the ref slot is updated first time with new position
and the second time the value is the ref slot is the old position as expected.
This can be worked around if we want.
*/
if(obj_mark_in_vt(p_obj)){
collector_tracestack_push(collector, p_obj);
#ifdef GC_GEN_STATS
gc_gen_collector_update_rootset_ref_num(stats);
gc_gen_collector_update_marked_obj_stats_major(stats);
#endif
}
}
root_set = pool_iterator_next(metadata->gc_rootset_pool);
}
/* put back the last trace_stack task */
pool_put_entry(metadata->mark_task_pool, collector->trace_stack);
/* second step: iterate over the mark tasks and scan objects */
/* get a task buf for the mark stack */
collector->trace_stack = free_task_pool_get_entry(metadata);
retry:
Vector_Block* mark_task = pool_get_entry(metadata->mark_task_pool);
while(mark_task){
POINTER_SIZE_INT* iter = vector_block_iterator_init(mark_task);
while(!vector_block_iterator_end(mark_task,iter)){
Partial_Reveal_Object* p_obj = (Partial_Reveal_Object *)*iter;
iter = vector_block_iterator_advance(mark_task,iter);
/* FIXME:: we should not let mark_task empty during working, , other may want to steal it.
degenerate my stack into mark_task, and grab another mark_task */
trace_object(collector, p_obj);
}
/* run out one task, put back to the pool and grab another task */
vector_stack_clear(mark_task);
pool_put_entry(metadata->free_task_pool, mark_task);
mark_task = pool_get_entry(metadata->mark_task_pool);
}
/* termination detection. This is also a barrier.
NOTE:: We can simply spin waiting for num_finished_collectors, because each
generated new task would surely be processed by its generating collector eventually.
So code below is only for load balance optimization. */
atomic_inc32(&num_finished_collectors);
while(num_finished_collectors != num_active_collectors){
if( !pool_is_empty(metadata->mark_task_pool)){
atomic_dec32(&num_finished_collectors);
goto retry;
}
}
/* put back the last mark stack to the free pool */
mark_task = (Vector_Block*)collector->trace_stack;
vector_stack_clear(mark_task);
pool_put_entry(metadata->free_task_pool, mark_task);
collector->trace_stack = NULL;
return;
}
static void collector_trace_rootsets(Collector* collector)
{
GC* gc = collector->gc;
GC_Metadata* metadata = gc->metadata;
#ifdef GC_GEN_STATS
GC_Gen_Collector_Stats* stats = (GC_Gen_Collector_Stats*)collector->stats;
#endif
unsigned int num_active_collectors = gc->num_active_collectors;
atomic_cas32( &num_finished_collectors, 0, num_active_collectors);
Space* space = collector->collect_space;
collector->trace_stack = free_task_pool_get_entry(metadata);
/* find root slots saved by 1. active mutators, 2. exited mutators, 3. last cycle collectors */
Vector_Block* root_set = pool_iterator_next(metadata->gc_rootset_pool);
/* first step: copy all root objects to trace tasks. */
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: copy root objects to trace stack ......");
while(root_set){
POINTER_SIZE_INT* iter = vector_block_iterator_init(root_set);
while(!vector_block_iterator_end(root_set,iter)){
REF *p_ref = (REF *)*iter;
iter = vector_block_iterator_advance(root_set,iter);
if(!*p_ref) continue; /* root ref cann't be NULL, but remset can be */
Partial_Reveal_Object *p_obj = read_slot(p_ref);
#ifdef GC_GEN_STATS
gc_gen_collector_update_rootset_ref_num(stats);
#endif
if(obj_belongs_to_nos(p_obj)){
collector_tracestack_push(collector, p_ref);
}
}
root_set = pool_iterator_next(metadata->gc_rootset_pool);
}
/* put back the last trace_stack task */
pool_put_entry(metadata->mark_task_pool, collector->trace_stack);
/* second step: iterate over the trace tasks and forward objects */
collector->trace_stack = free_task_pool_get_entry(metadata);
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: finish copying root objects to trace stack.");
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: trace and forward objects ......");
retry:
Vector_Block* trace_task = pool_get_entry(metadata->mark_task_pool);
while(trace_task){
POINTER_SIZE_INT* iter = vector_block_iterator_init(trace_task);
while(!vector_block_iterator_end(trace_task,iter)){
REF *p_ref = (REF *)*iter;
iter = vector_block_iterator_advance(trace_task,iter);
assert(*p_ref); /* a task can't be NULL, it was checked before put into the task stack */
#ifdef PREFETCH_SUPPORTED
/* DO PREFETCH */
if( mark_prefetch ) {
if(!vector_block_iterator_end(trace_task, iter)) {
REF *pref= (REF*) *iter;
PREFETCH( read_slot(pref));
}
}
#endif
/* in sequential version, we only trace same object once, but we were using a local hashset for that,
which couldn't catch the repetition between multiple collectors. This is subject to more study. */
/* FIXME:: we should not let root_set empty during working, other may want to steal it.
degenerate my stack into root_set, and grab another stack */
/* a task has to belong to collected space, it was checked before put into the stack */
trace_object(collector, p_ref);
if(collector->result == FALSE) break; /* force return */
}
vector_stack_clear(trace_task);
pool_put_entry(metadata->free_task_pool, trace_task);
if(collector->result == FALSE){
gc_task_pool_clear(metadata->mark_task_pool);
break; /* force return */
}
trace_task = pool_get_entry(metadata->mark_task_pool);
}
atomic_inc32(&num_finished_collectors);
while(num_finished_collectors != num_active_collectors){
if( pool_is_empty(metadata->mark_task_pool)) continue;
/* we can't grab the task here, because of a race condition. If we grab the task,
and the pool is empty, other threads may fall to this barrier and then pass. */
atomic_dec32(&num_finished_collectors);
goto retry;
}
TRACE2("gc.process", "GC: collector["<<((POINTER_SIZE_INT)collector->thread_handle)<<"]: finish tracing and forwarding objects.");
/* now we are done, but each collector has a private stack that is empty */
trace_task = (Vector_Block*)collector->trace_stack;
vector_stack_clear(trace_task);
pool_put_entry(metadata->free_task_pool, trace_task);
collector->trace_stack = NULL;
return;
}
