Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/dirtyCardQueue.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1HotCardCache.hpp"

 #include "gc_implementation/g1/g1RemSet.hpp"

 #include "runtime/atomic.hpp"

 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):

   _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}

 void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {

   if (default_use_cache()) {

     _use_cache = true;

     _hot_cache_size = (size_t)1 << G1ConcRSLogCacheSize;

     _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);

     reset_hot_cache_internal();

     // For refining the cards in the hot cache in parallel

     _hot_cache_par_chunk_size = (int)(ParallelGCThreads > 0 ? ClaimChunkSize : _hot_cache_size);

     _hot_cache_par_claimed_idx = 0;

     _card_counts.initialize(card_counts_storage);

   }

 }

 G1HotCardCache::~G1HotCardCache() {

   if (default_use_cache()) {

     assert(_hot_cache != NULL, "Logic");

     FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);

   }

 }

 jbyte* G1HotCardCache::insert(jbyte* card_ptr) {

   uint count = _card_counts.add_card_count(card_ptr);

   if (!_card_counts.is_hot(count)) {

     // The card is not hot so do not store it in the cache;

     // return it for immediate refining.

     return card_ptr;

   }

   // Otherwise, the card is hot.

   size_t index = Atomic::add_ptr((intptr_t)1, (volatile intptr_t*)&_hot_cache_idx) - 1;

   size_t masked_index = index & (_hot_cache_size - 1);

   jbyte* current_ptr = _hot_cache[masked_index];

   // Try to store the new card pointer into the cache. Compare-and-swap to guard

   // against the unlikely event of a race resulting in another card pointer to

   // have already been written to the cache. In this case we will return

   // card_ptr in favor of the other option, which would be starting over. This

   // should be OK since card_ptr will likely be the older card already when/if

   // this ever happens.

   jbyte* previous_ptr = (jbyte*)Atomic::cmpxchg_ptr(card_ptr,

                                                     &_hot_cache[masked_index],

                                                     current_ptr);

   return (previous_ptr == current_ptr) ? previous_ptr : card_ptr;

 }

 void G1HotCardCache::drain(uint worker_i,

                            G1RemSet* g1rs,

                            DirtyCardQueue* into_cset_dcq) {

   if (!default_use_cache()) {

     assert(_hot_cache == NULL, "Logic");

     return;

   }

   assert(_hot_cache != NULL, "Logic");

   assert(!use_cache(), "cache should be disabled");

   while (_hot_cache_par_claimed_idx < _hot_cache_size) {

     size_t end_idx = Atomic::add_ptr((intptr_t)_hot_cache_par_chunk_size,

                                      (volatile intptr_t*)&_hot_cache_par_claimed_idx);

     size_t start_idx = end_idx - _hot_cache_par_chunk_size;

     // The current worker has successfully claimed the chunk [start_idx..end_idx)

     end_idx = MIN2(end_idx, _hot_cache_size);

     for (size_t i = start_idx; i < end_idx; i++) {

       jbyte* card_ptr = _hot_cache[i];

       if (card_ptr != NULL) {

         if (g1rs->refine_card(card_ptr, worker_i, true)) {

           // The part of the heap spanned by the card contains references

           // that point into the current collection set.

           // We need to record the card pointer in the DirtyCardQueueSet

           // that we use for such cards.

           //

           // The only time we care about recording cards that contain

           // references that point into the collection set is during

           // RSet updating while within an evacuation pause.

           // In this case worker_i should be the id of a GC worker thread

           assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");

           assert(worker_i < ParallelGCThreads,

                  err_msg("incorrect worker id: %u", worker_i));

           into_cset_dcq->enqueue(card_ptr);

         }

       } else {

         break;

       }

     }

   }

   // The existing entries in the hot card cache, which were just refined

   // above, are discarded prior to re-enabling the cache near the end of the GC.

 }

 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {

   _card_counts.clear_region(hr);

 }

 void G1HotCardCache::reset_card_counts() {

   _card_counts.clear_all();

 }