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6962589: remove breadth first scanning code from parallel gc
Remove the breadth-first copying order from ParallelScavenge and use depth-first by default. Reviewed-by: jcoomes, ysr, johnc
This commit is contained in:
Antonios Printezis
parent
3a2b2b4fd8
commit
38ab95c64b
30 changed files with 63 additions and 541 deletions
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@ -27,7 +27,6 @@
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PSPromotionManager** PSPromotionManager::_manager_array = NULL;
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OopStarTaskQueueSet* PSPromotionManager::_stack_array_depth = NULL;
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OopTaskQueueSet* PSPromotionManager::_stack_array_breadth = NULL;
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PSOldGen* PSPromotionManager::_old_gen = NULL;
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MutableSpace* PSPromotionManager::_young_space = NULL;
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@ -42,23 +41,14 @@ void PSPromotionManager::initialize() {
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_manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 );
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guarantee(_manager_array != NULL, "Could not initialize promotion manager");
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if (UseDepthFirstScavengeOrder) {
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_stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
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guarantee(_stack_array_depth != NULL, "Count not initialize promotion manager");
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} else {
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_stack_array_breadth = new OopTaskQueueSet(ParallelGCThreads);
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guarantee(_stack_array_breadth != NULL, "Count not initialize promotion manager");
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}
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_stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
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guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");
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// Create and register the PSPromotionManager(s) for the worker threads.
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for(uint i=0; i<ParallelGCThreads; i++) {
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_manager_array[i] = new PSPromotionManager();
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guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager");
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if (UseDepthFirstScavengeOrder) {
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stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());
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} else {
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stack_array_breadth()->register_queue(i, _manager_array[i]->claimed_stack_breadth());
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}
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stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());
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}
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// The VMThread gets its own PSPromotionManager, which is not available
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@ -93,11 +83,7 @@ void PSPromotionManager::post_scavenge() {
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TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());
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for (uint i = 0; i < ParallelGCThreads + 1; i++) {
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PSPromotionManager* manager = manager_array(i);
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if (UseDepthFirstScavengeOrder) {
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assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
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} else {
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assert(manager->claimed_stack_breadth()->is_empty(), "should be empty");
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}
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assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
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manager->flush_labs();
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}
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}
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@ -105,10 +91,8 @@ void PSPromotionManager::post_scavenge() {
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#if TASKQUEUE_STATS
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void
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PSPromotionManager::print_taskqueue_stats(uint i) const {
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const TaskQueueStats& stats = depth_first() ?
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_claimed_stack_depth.stats : _claimed_stack_breadth.stats;
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tty->print("%3u ", i);
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stats.print();
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_claimed_stack_depth.stats.print();
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tty->cr();
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}
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@ -128,8 +112,7 @@ static const char* const pm_stats_hdr[] = {
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void
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PSPromotionManager::print_stats() {
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const bool df = UseDepthFirstScavengeOrder;
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tty->print_cr("== GC Task Stats (%s-First), GC %3d", df ? "Depth" : "Breadth",
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tty->print_cr("== GC Tasks Stats, GC %3d",
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Universe::heap()->total_collections());
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tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();
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@ -147,9 +130,7 @@ PSPromotionManager::print_stats() {
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void
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PSPromotionManager::reset_stats() {
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TaskQueueStats& stats = depth_first() ?
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claimed_stack_depth()->stats : claimed_stack_breadth()->stats;
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stats.reset();
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claimed_stack_depth()->stats.reset();
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_masked_pushes = _masked_steals = 0;
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_arrays_chunked = _array_chunks_processed = 0;
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}
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@ -158,19 +139,13 @@ PSPromotionManager::reset_stats() {
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PSPromotionManager::PSPromotionManager() {
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ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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_depth_first = UseDepthFirstScavengeOrder;
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// We set the old lab's start array.
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_old_lab.set_start_array(old_gen()->start_array());
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uint queue_size;
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if (depth_first()) {
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claimed_stack_depth()->initialize();
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queue_size = claimed_stack_depth()->max_elems();
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} else {
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claimed_stack_breadth()->initialize();
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queue_size = claimed_stack_breadth()->max_elems();
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}
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claimed_stack_depth()->initialize();
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queue_size = claimed_stack_depth()->max_elems();
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_totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
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if (_totally_drain) {
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@ -205,14 +180,11 @@ void PSPromotionManager::reset() {
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_old_lab.initialize(MemRegion(lab_base, (size_t)0));
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_old_gen_is_full = false;
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_prefetch_queue.clear();
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TASKQUEUE_STATS_ONLY(reset_stats());
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}
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void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
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assert(depth_first(), "invariant");
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assert(claimed_stack_depth()->overflow_stack() != NULL, "invariant");
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totally_drain = totally_drain || _totally_drain;
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@ -250,50 +222,6 @@ void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
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assert(tq->overflow_empty(), "Sanity");
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}
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void PSPromotionManager::drain_stacks_breadth(bool totally_drain) {
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assert(!depth_first(), "invariant");
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assert(claimed_stack_breadth()->overflow_stack() != NULL, "invariant");
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totally_drain = totally_drain || _totally_drain;
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#ifdef ASSERT
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ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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MutableSpace* to_space = heap->young_gen()->to_space();
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MutableSpace* old_space = heap->old_gen()->object_space();
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MutableSpace* perm_space = heap->perm_gen()->object_space();
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#endif /* ASSERT */
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OverflowTaskQueue<oop>* const tq = claimed_stack_breadth();
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do {
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oop obj;
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// Drain overflow stack first, so other threads can steal from
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// claimed stack while we work.
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while (tq->pop_overflow(obj)) {
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obj->copy_contents(this);
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}
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if (totally_drain) {
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while (tq->pop_local(obj)) {
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obj->copy_contents(this);
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}
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} else {
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while (tq->size() > _target_stack_size && tq->pop_local(obj)) {
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obj->copy_contents(this);
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}
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}
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// If we could not find any other work, flush the prefetch queue
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if (tq->is_empty()) {
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flush_prefetch_queue();
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}
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} while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());
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assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
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assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
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assert(tq->overflow_empty(), "Sanity");
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}
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void PSPromotionManager::flush_labs() {
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assert(stacks_empty(), "Attempt to flush lab with live stack");
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@ -319,7 +247,7 @@ void PSPromotionManager::flush_labs() {
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// performance.
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//
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oop PSPromotionManager::copy_to_survivor_space(oop o, bool depth_first) {
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oop PSPromotionManager::copy_to_survivor_space(oop o) {
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assert(PSScavenge::should_scavenge(&o), "Sanity");
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oop new_obj = NULL;
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@ -423,24 +351,20 @@ oop PSPromotionManager::copy_to_survivor_space(oop o, bool depth_first) {
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assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
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}
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if (depth_first) {
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// Do the size comparison first with new_obj_size, which we
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// already have. Hopefully, only a few objects are larger than
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// _min_array_size_for_chunking, and most of them will be arrays.
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// So, the is->objArray() test would be very infrequent.
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if (new_obj_size > _min_array_size_for_chunking &&
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new_obj->is_objArray() &&
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PSChunkLargeArrays) {
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// we'll chunk it
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oop* const masked_o = mask_chunked_array_oop(o);
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push_depth(masked_o);
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TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
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} else {
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// we'll just push its contents
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new_obj->push_contents(this);
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}
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// Do the size comparison first with new_obj_size, which we
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// already have. Hopefully, only a few objects are larger than
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// _min_array_size_for_chunking, and most of them will be arrays.
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// So, the is->objArray() test would be very infrequent.
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if (new_obj_size > _min_array_size_for_chunking &&
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new_obj->is_objArray() &&
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PSChunkLargeArrays) {
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// we'll chunk it
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oop* const masked_o = mask_chunked_array_oop(o);
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push_depth(masked_o);
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TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
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} else {
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push_breadth(new_obj);
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// we'll just push its contents
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new_obj->push_contents(this);
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}
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} else {
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// We lost, someone else "owns" this object
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@ -537,13 +461,7 @@ oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
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// We won any races, we "own" this object.
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assert(obj == obj->forwardee(), "Sanity");
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if (depth_first()) {
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obj->push_contents(this);
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} else {
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// Don't bother incrementing the age, just push
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// onto the claimed_stack..
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push_breadth(obj);
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}
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obj->push_contents(this);
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// Save the mark if needed
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PSScavenge::oop_promotion_failed(obj, obj_mark);
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