1 /*
  2  * Copyright (c) 2001, 2019, 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  *

 57 // threads to locate PRTs without locking, but threads attempting to alter
 58 // a bucket list obtain a lock.  This means that any failing attempt to
 59 // find a PRT must be retried with the lock.  It might seem dangerous that
 60 // a read can find a PRT that is concurrently deleted.  This is all right,
 61 // because:
 62 //
 63 //   1) We only actually free PRT's at safe points (though we reuse them at
 64 //      other times).
 65 //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
 66 //      it's _coarse_map bit is set, so the that we were attempting to add
 67 //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
 68 //      thinking the PRT is for a different region, does no harm.
 69 
 70 class OtherRegionsTable {
 71   G1CollectedHeap* _g1h;
 72   Mutex*           _m;
 73 
 74   size_t volatile _num_occupied;
 75 
 76   // These are protected by "_m".
 77   CHeapBitMap _coarse_map;
 78   size_t      _n_coarse_entries;
 79   static jint _n_coarsenings;
 80 
 81   PerRegionTable** _fine_grain_regions;
 82   size_t           _n_fine_entries;
 83 
 84   // The fine grain remembered sets are linked together using
 85   // their 'next' fields.
 86   // This allows fast bulk freeing of all the fine grain remembered
 87   // set entries, and fast finding of all of them without iterating
 88   // over the _fine_grain_regions table.
 89   PerRegionTable * _first_all_fine_prts;
 90   PerRegionTable * _last_all_fine_prts;
 91 
 92   // Used to sample a subset of the fine grain PRTs to determine which
 93   // PRT to evict and coarsen.
 94   size_t        _fine_eviction_start;
 95   static size_t _fine_eviction_stride;
 96   static size_t _fine_eviction_sample_size;
 97 
 98   SparsePRT   _sparse_table;
 99 

  1 /*
  2  * Copyright (c) 2001, 2020, 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  *

 57 // threads to locate PRTs without locking, but threads attempting to alter
 58 // a bucket list obtain a lock.  This means that any failing attempt to
 59 // find a PRT must be retried with the lock.  It might seem dangerous that
 60 // a read can find a PRT that is concurrently deleted.  This is all right,
 61 // because:
 62 //
 63 //   1) We only actually free PRT's at safe points (though we reuse them at
 64 //      other times).
 65 //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
 66 //      it's _coarse_map bit is set, so the that we were attempting to add
 67 //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
 68 //      thinking the PRT is for a different region, does no harm.
 69 
 70 class OtherRegionsTable {
 71   G1CollectedHeap* _g1h;
 72   Mutex*           _m;
 73 
 74   size_t volatile _num_occupied;
 75 
 76   // These are protected by "_m".
 77   CHeapBitMap   _coarse_map;
 78   bool volatile _has_coarse_entries;
 79   static jint   _n_coarsenings;
 80 
 81   PerRegionTable** _fine_grain_regions;
 82   size_t           _n_fine_entries;
 83 
 84   // The fine grain remembered sets are linked together using
 85   // their 'next' fields.
 86   // This allows fast bulk freeing of all the fine grain remembered
 87   // set entries, and fast finding of all of them without iterating
 88   // over the _fine_grain_regions table.
 89   PerRegionTable * _first_all_fine_prts;
 90   PerRegionTable * _last_all_fine_prts;
 91 
 92   // Used to sample a subset of the fine grain PRTs to determine which
 93   // PRT to evict and coarsen.
 94   size_t        _fine_eviction_start;
 95   static size_t _fine_eviction_stride;
 96   static size_t _fine_eviction_sample_size;
 97 
 98   SparsePRT   _sparse_table;
 99