view src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp @ 889:15c5903cf9e1

6865703: G1: Parallelize hot card cache cleanup Summary: Have the GC worker threads clear the hot card cache in parallel by having each worker thread claim a chunk of the card cache and process the cards in that chunk. The size of the chunks that each thread will claim is determined at VM initialization from the size of the card cache and the number of worker threads. Reviewed-by: jmasa, tonyp
author johnc
date Mon, 03 Aug 2009 12:59:30 -0700
parents 215f81b4d9b3
children 6cb8e9df7174
line wrap: on
line source
 * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit if you need additional information or
 * have any questions.

// Forward decl
class ConcurrentG1RefineThread;
class G1RemSet;

class ConcurrentG1Refine: public CHeapObj {
  ConcurrentG1RefineThread** _threads;
  int _n_threads;
  // The cache for card refinement.
  bool     _use_cache;
  bool     _def_use_cache;
  size_t _n_periods;
  size_t _total_cards;
  size_t _total_travs;

  unsigned char* _card_counts;
  unsigned       _n_card_counts;
  const jbyte*   _ct_bot;
  unsigned*      _cur_card_count_histo;
  unsigned*      _cum_card_count_histo;

  jbyte**      _hot_cache;
  int          _hot_cache_size;
  int          _n_hot;
  int          _hot_cache_idx;

  int          _hot_cache_par_chunk_size;
  volatile int _hot_cache_par_claimed_idx;

  // Returns the count of this card after incrementing it.
  int add_card_count(jbyte* card_ptr);

  void print_card_count_histo_range(unsigned* histo, int from, int to,
                                    float& cum_card_pct,
                                    float& cum_travs_pct);

  void init(); // Accomplish some initialization that has to wait.
  void stop();

  // Iterate over the conc refine threads
  void threads_do(ThreadClosure *tc);

  // If this is the first entry for the slot, writes into the cache and
  // returns NULL.  If it causes an eviction, returns the evicted pointer.
  // Otherwise, its a cache hit, and returns NULL.
  jbyte* cache_insert(jbyte* card_ptr);

  // Process the cached entries.
  void clean_up_cache(int worker_i, G1RemSet* g1rs);

  // Set up for parallel processing of the cards in the hot cache
  void clear_hot_cache_claimed_index() {
    _hot_cache_par_claimed_idx = 0;

  // Discard entries in the hot cache.
  void clear_hot_cache() {
    _hot_cache_idx = 0; _n_hot = 0;

  bool hot_cache_is_empty() { return _n_hot == 0; }

  bool use_cache() { return _use_cache; }
  void set_use_cache(bool b) {
    if (b) _use_cache = _def_use_cache;
    else   _use_cache = false;

  void clear_and_record_card_counts();
  void print_final_card_counts();

  static size_t thread_num();