jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@02f49b66361a (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@02f49b66361a (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp

Mon, 28 Mar 2011 10:58:54 -0700

author: johnc
date: Mon, 28 Mar 2011 10:58:54 -0700
changeset 2713: 02f49b66361a
parent 2314: f95d63e2154a
child 2790: edd9b016deb6
permissions: -rw-r--r--

7026932: G1: No need to abort VM when card count cache expansion fails
Summary: Manage allocation/freeing of the card cache counts and epochs arrays directly so that an allocation failure while attempting to expand these arrays does not abort the JVM. Failure to expand these arrays is not fatal.
Reviewed-by: iveresov, tonyp

 /*
  * Copyright (c) 2001, 2011, 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.
  *
  */
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
 #include "memory/allocation.hpp"
 #include "memory/cardTableModRefBS.hpp"
 #include "runtime/thread.hpp"
 #include "utilities/globalDefinitions.hpp"
 // Forward decl
 class ConcurrentG1RefineThread;
 class G1RemSet;
 class ConcurrentG1Refine: public CHeapObj {
   ConcurrentG1RefineThread** _threads;
   int _n_threads;
   int _n_worker_threads;
  /*
   * The value of the update buffer queue length falls into one of 3 zones:
   * green, yellow, red. If the value is in [0, green) nothing is
   * done, the buffers are left unprocessed to enable the caching effect of the
   * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement
   * threads are gradually activated. In [yellow, red) all threads are
   * running. If the length becomes red (max queue length) the mutators start
   * processing the buffers.
   *
   * There are some interesting cases (when G1UseAdaptiveConcRefinement
   * is turned off):
   * 1) green = yellow = red = 0. In this case the mutator will process all
   *    buffers. Except for those that are created by the deferred updates
   *    machinery during a collection.
   * 2) green = 0. Means no caching. Can be a good way to minimize the
   *    amount of time spent updating rsets during a collection.
   */
   int _green_zone;
   int _yellow_zone;
   int _red_zone;
   int _thread_threshold_step;
   // Reset the threshold step value based of the current zone boundaries.
   void reset_threshold_step();
   // The cache for card refinement.
   bool   _use_cache;
   bool   _def_use_cache;
   size_t _n_periods;    // Used as clearing epoch
   // An evicting cache of the number of times each card
   // is accessed. Reduces, but does not eliminate, the amount
   // of duplicated processing of dirty cards.
   enum SomePrivateConstants {
     epoch_bits           = 32,
     card_num_shift       = epoch_bits,
     epoch_mask           = AllBits,
     card_num_mask        = AllBits,
     // The initial cache size is approximately this fraction
     // of a maximal cache (i.e. the size needed for all cards
     // in the heap)
     InitialCacheFraction = 512
   };
   const static julong card_num_mask_in_place =
                         (julong) card_num_mask << card_num_shift;
   typedef struct {
     julong _value;      // |  card_num   |  epoch   |
   } CardEpochCacheEntry;
   julong make_epoch_entry(unsigned int card_num, unsigned int epoch) {
     assert(0 <= card_num && card_num < _max_cards, "Bounds");
     assert(0 <= epoch && epoch <= _n_periods, "must be");
     return ((julong) card_num << card_num_shift) | epoch;
   }
   unsigned int extract_epoch(julong v) {
     return (v & epoch_mask);
   }
   unsigned int extract_card_num(julong v) {
     return (v & card_num_mask_in_place) >> card_num_shift;
   }
   typedef struct {
     unsigned char _count;
     unsigned char _evict_count;
   } CardCountCacheEntry;
   CardCountCacheEntry* _card_counts;
   CardEpochCacheEntry* _card_epochs;
   // The current number of buckets in the card count cache
   size_t _n_card_counts;
   // The number of cards for the entire reserved heap
   size_t _max_cards;
   // The max number of buckets for the card counts and epochs caches.
   // This is the maximum that the counts and epochs will grow to.
   // It is specified as a fraction or percentage of _max_cards using
   // G1MaxHotCardCountSizePercent.
   size_t _max_n_card_counts;
   // Possible sizes of the cache: odd primes that roughly double in size.
   // (See jvmtiTagMap.cpp).
   enum {
     MAX_CC_CACHE_INDEX = 15    // maximum index into the cache size array.
   };
   static size_t _cc_cache_sizes[MAX_CC_CACHE_INDEX];
   // The index in _cc_cache_sizes corresponding to the size of
   // _card_counts.
   int _cache_size_index;
   bool _expand_card_counts;
   const jbyte* _ct_bot;
   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;
   // Needed to workaround 6817995
   CardTableModRefBS* _ct_bs;
   G1CollectedHeap*   _g1h;
   // Helper routine for expand_card_count_cache().
   // The arrays used to hold the card counts and the epochs must have
   // a 1:1 correspondence. Hence they are allocated and freed together.
   // Returns true if the allocations of both the counts and epochs
   // were successful; false otherwise.
   bool allocate_card_count_cache(size_t n,
                                  CardCountCacheEntry** counts,
                                  CardEpochCacheEntry** epochs);
   // Expands the arrays that hold the card counts and epochs
   // to the cache size at index. Returns true if the expansion/
   // allocation was successful; false otherwise.
   bool expand_card_count_cache(int index);
   // hash a given key (index of card_ptr) with the specified size
   static unsigned int hash(size_t key, size_t size) {
     return (unsigned int) key % size;
   }
   // hash a given key (index of card_ptr)
   unsigned int hash(size_t key) {
     return hash(key, _n_card_counts);
   }
   unsigned ptr_2_card_num(jbyte* card_ptr) {
     return (unsigned) (card_ptr - _ct_bot);
   }
   jbyte* card_num_2_ptr(unsigned card_num) {
     return (jbyte*) (_ct_bot + card_num);
   }
   // Returns the count of this card after incrementing it.
   jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer);
   // Returns true if this card is in a young region
   bool is_young_card(jbyte* card_ptr);
  public:
   ConcurrentG1Refine();
   ~ConcurrentG1Refine();
   void init(); // Accomplish some initialization that has to wait.
   void stop();
   void reinitialize_threads();
   // 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, bool* defer);
   // Process the cached entries.
   void clean_up_cache(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
   // 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();
   static int thread_num();
   void print_worker_threads_on(outputStream* st) const;
   void set_green_zone(int x)  { _green_zone = x;  }
   void set_yellow_zone(int x) { _yellow_zone = x; }
   void set_red_zone(int x)    { _red_zone = x;    }
   int green_zone() const      { return _green_zone;  }
   int yellow_zone() const     { return _yellow_zone; }
   int red_zone() const        { return _red_zone;    }
   int total_thread_num() const  { return _n_threads;        }
   int worker_thread_num() const { return _n_worker_threads; }
   int thread_threshold_step() const { return _thread_threshold_step; }
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@02f49b66361a (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp