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src/hotspot/share/gc/g1/g1FromCardCache.hpp

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   1 /*
   2  * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
  26 #define SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/ostream.hpp"
  30 
  31 // G1FromCardCache remembers the most recently processed card on the heap on
  32 // a per-region and per-thread basis.
  33 class G1FromCardCache : public AllStatic {
  34  private:
  35   // Array of card indices. Indexed by heap region (rows) and thread (columns) to minimize
  36   // thread contention.
  37   // This order minimizes the time to clear all entries for a given region during region
  38   // freeing. I.e. a single clear of a single memory area instead of multiple separate
  39   // accesses with a large stride per region.
  40   static uintptr_t** _cache;
  41   static uint _max_regions;
  42   static size_t _static_mem_size;
  43 #ifdef ASSERT
  44   static uint _max_workers;
  45 
  46   static void check_bounds(uint worker_id, uint region_idx) {
  47     assert(worker_id < _max_workers, "Worker_id %u is larger than maximum %u", worker_id, _max_workers);
  48     assert(region_idx < _max_regions, "Region_idx %u is larger than maximum %u", region_idx, _max_regions);
  49   }
  50 #endif
  51 
  52  public:
  53   static const uintptr_t InvalidCard = UINTPTR_MAX;


  54 

  55   static void clear(uint region_idx);
  56 
  57   // Returns true if the given card is in the cache at the given location, or
  58   // replaces the card at that location and returns false.
  59   static bool contains_or_replace(uint worker_id, uint region_idx, uintptr_t card) {
  60     uintptr_t card_in_cache = at(worker_id, region_idx);
  61     if (card_in_cache == card) {
  62       return true;
  63     } else {
  64       set(worker_id, region_idx, card);
  65       return false;
  66     }
  67   }
  68 
  69   static uintptr_t at(uint worker_id, uint region_idx) {
  70     DEBUG_ONLY(check_bounds(worker_id, region_idx);)
  71     return _cache[region_idx][worker_id];
  72   }
  73 
  74   static void set(uint worker_id, uint region_idx, uintptr_t val) {
   1 /*
   2  * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
  26 #define SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/ostream.hpp"
  30 
  31 // G1FromCardCache remembers the most recently processed card on the heap on
  32 // a per-region and per-thread basis.
  33 class G1FromCardCache : public AllStatic {
  34 private:
  35   // Array of card indices. Indexed by heap region (rows) and thread (columns) to minimize
  36   // thread contention.
  37   // This order minimizes the time to clear all entries for a given region during region
  38   // freeing. I.e. a single clear of a single memory area instead of multiple separate
  39   // accesses with a large stride per region.
  40   static uintptr_t** _cache;
  41   static uint _max_regions;
  42   static size_t _static_mem_size;
  43 #ifdef ASSERT
  44   static uint _max_workers;
  45 
  46   static void check_bounds(uint worker_id, uint region_idx) {
  47     assert(worker_id < _max_workers, "Worker_id %u is larger than maximum %u", worker_id, _max_workers);
  48     assert(region_idx < _max_regions, "Region_idx %u is larger than maximum %u", region_idx, _max_regions);
  49   }
  50 #endif
  51 
  52   // This card index indicates "no card for that entry" yet. This allows us to use the OS
  53   // lazy backing of memory with zero-filled pages to avoid initial actual memory use.
  54   // This means that the heap must not contain card zero.
  55   static const uintptr_t InvalidCard = 0;
  56 
  57 public:
  58   static void clear(uint region_idx);
  59 
  60   // Returns true if the given card is in the cache at the given location, or
  61   // replaces the card at that location and returns false.
  62   static bool contains_or_replace(uint worker_id, uint region_idx, uintptr_t card) {
  63     uintptr_t card_in_cache = at(worker_id, region_idx);
  64     if (card_in_cache == card) {
  65       return true;
  66     } else {
  67       set(worker_id, region_idx, card);
  68       return false;
  69     }
  70   }
  71 
  72   static uintptr_t at(uint worker_id, uint region_idx) {
  73     DEBUG_ONLY(check_bounds(worker_id, region_idx);)
  74     return _cache[region_idx][worker_id];
  75   }
  76 
  77   static void set(uint worker_id, uint region_idx, uintptr_t val) {
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