johnc@5078: /*
redestad@7653:  * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
johnc@5078:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
johnc@5078:  *
johnc@5078:  * This code is free software; you can redistribute it and/or modify it
johnc@5078:  * under the terms of the GNU General Public License version 2 only, as
johnc@5078:  * published by the Free Software Foundation.
johnc@5078:  *
johnc@5078:  * This code is distributed in the hope that it will be useful, but WITHOUT
johnc@5078:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
johnc@5078:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
johnc@5078:  * version 2 for more details (a copy is included in the LICENSE file that
johnc@5078:  * accompanied this code).
johnc@5078:  *
johnc@5078:  * You should have received a copy of the GNU General Public License version
johnc@5078:  * 2 along with this work; if not, write to the Free Software Foundation,
johnc@5078:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
johnc@5078:  *
johnc@5078:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
johnc@5078:  * or visit www.oracle.com if you need additional information or have any
johnc@5078:  * questions.
johnc@5078:  *
johnc@5078:  */
johnc@5078: 
johnc@5078: #include "precompiled.hpp"
johnc@5078: #include "gc_implementation/g1/dirtyCardQueue.hpp"
johnc@5078: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
johnc@5078: #include "gc_implementation/g1/g1HotCardCache.hpp"
johnc@5078: #include "gc_implementation/g1/g1RemSet.hpp"
johnc@5078: #include "runtime/atomic.hpp"
johnc@5078: 
johnc@5078: G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
johnc@5078:   _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
johnc@5078: 
tschatzl@7051: void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {
johnc@5078:   if (default_use_cache()) {
johnc@5078:     _use_cache = true;
johnc@5078: 
redestad@7653:     _hot_cache_size = (size_t)1 << G1ConcRSLogCacheSize;
johnc@5078:     _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);
johnc@5078: 
redestad@7653:     reset_hot_cache_internal();
johnc@5078: 
johnc@5078:     // For refining the cards in the hot cache in parallel
mlarsson@7652:     _hot_cache_par_chunk_size = (int)(ParallelGCThreads > 0 ? ClaimChunkSize : _hot_cache_size);
johnc@5078:     _hot_cache_par_claimed_idx = 0;
johnc@5078: 
tschatzl@7051:     _card_counts.initialize(card_counts_storage);
johnc@5078:   }
johnc@5078: }
johnc@5078: 
johnc@5078: G1HotCardCache::~G1HotCardCache() {
johnc@5078:   if (default_use_cache()) {
johnc@5078:     assert(_hot_cache != NULL, "Logic");
johnc@5078:     FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);
johnc@5078:   }
johnc@5078: }
johnc@5078: 
johnc@5078: jbyte* G1HotCardCache::insert(jbyte* card_ptr) {
johnc@5078:   uint count = _card_counts.add_card_count(card_ptr);
johnc@5078:   if (!_card_counts.is_hot(count)) {
johnc@5078:     // The card is not hot so do not store it in the cache;
johnc@5078:     // return it for immediate refining.
johnc@5078:     return card_ptr;
johnc@5078:   }
redestad@7653:   // Otherwise, the card is hot.
redestad@7653:   size_t index = Atomic::add_ptr((intptr_t)1, (volatile intptr_t*)&_hot_cache_idx) - 1;
redestad@7653:   size_t masked_index = index & (_hot_cache_size - 1);
redestad@7653:   jbyte* current_ptr = _hot_cache[masked_index];
johnc@5078: 
redestad@7653:   // Try to store the new card pointer into the cache. Compare-and-swap to guard
redestad@7653:   // against the unlikely event of a race resulting in another card pointer to
redestad@7653:   // have already been written to the cache. In this case we will return
redestad@7653:   // card_ptr in favor of the other option, which would be starting over. This
redestad@7653:   // should be OK since card_ptr will likely be the older card already when/if
redestad@7653:   // this ever happens.
redestad@7653:   jbyte* previous_ptr = (jbyte*)Atomic::cmpxchg_ptr(card_ptr,
redestad@7653:                                                     &_hot_cache[masked_index],
redestad@7653:                                                     current_ptr);
redestad@7653:   return (previous_ptr == current_ptr) ? previous_ptr : card_ptr;
johnc@5078: }
johnc@5078: 
vkempik@6552: void G1HotCardCache::drain(uint worker_i,
johnc@5078:                            G1RemSet* g1rs,
johnc@5078:                            DirtyCardQueue* into_cset_dcq) {
johnc@5078:   if (!default_use_cache()) {
johnc@5078:     assert(_hot_cache == NULL, "Logic");
johnc@5078:     return;
johnc@5078:   }
johnc@5078: 
johnc@5078:   assert(_hot_cache != NULL, "Logic");
johnc@5078:   assert(!use_cache(), "cache should be disabled");
redestad@7653:   while (_hot_cache_par_claimed_idx < _hot_cache_size) {
redestad@7653:     size_t end_idx = Atomic::add_ptr((intptr_t)_hot_cache_par_chunk_size,
redestad@7653:                                      (volatile intptr_t*)&_hot_cache_par_claimed_idx);
redestad@7653:     size_t start_idx = end_idx - _hot_cache_par_chunk_size;
redestad@7653:     // The current worker has successfully claimed the chunk [start_idx..end_idx)
redestad@7653:     end_idx = MIN2(end_idx, _hot_cache_size);
redestad@7653:     for (size_t i = start_idx; i < end_idx; i++) {
redestad@7653:       jbyte* card_ptr = _hot_cache[i];
redestad@7653:       if (card_ptr != NULL) {
redestad@7653:         if (g1rs->refine_card(card_ptr, worker_i, true)) {
redestad@7653:           // The part of the heap spanned by the card contains references
redestad@7653:           // that point into the current collection set.
redestad@7653:           // We need to record the card pointer in the DirtyCardQueueSet
redestad@7653:           // that we use for such cards.
redestad@7653:           //
redestad@7653:           // The only time we care about recording cards that contain
redestad@7653:           // references that point into the collection set is during
redestad@7653:           // RSet updating while within an evacuation pause.
redestad@7653:           // In this case worker_i should be the id of a GC worker thread
redestad@7653:           assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");
redestad@7653:           assert(worker_i < ParallelGCThreads,
redestad@7653:                  err_msg("incorrect worker id: %u", worker_i));
johnc@5078: 
redestad@7653:           into_cset_dcq->enqueue(card_ptr);
johnc@5078:         }
redestad@7653:       } else {
redestad@7653:         break;
johnc@5078:       }
johnc@5078:     }
johnc@5078:   }
redestad@7653: 
johnc@5078:   // The existing entries in the hot card cache, which were just refined
johnc@5078:   // above, are discarded prior to re-enabling the cache near the end of the GC.
johnc@5078: }
johnc@5078: 
johnc@5078: void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
johnc@5078:   _card_counts.clear_region(hr);
johnc@5078: }
johnc@5078: 
johnc@5078: void G1HotCardCache::reset_card_counts() {
johnc@5078:   _card_counts.clear_all();
johnc@5078: }