1 /*

     2  * Copyright (c) 2001, 2017, 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 #include "precompiled.hpp"

    26 #include "gc/g1/g1BiasedArray.hpp"

    27 #include "gc/g1/g1RegionToSpaceMapper.hpp"

    28 #include "memory/allocation.inline.hpp"

    29 #include "memory/virtualspace.hpp"

    30 #include "services/memTracker.hpp"

    31 #include "utilities/align.hpp"

    32 #include "utilities/bitMap.inline.hpp"

    33 

    34 G1RegionToSpaceMapper::G1RegionToSpaceMapper(ReservedSpace rs,

    35                                              size_t used_size,

    36                                              size_t page_size,

    37                                              size_t region_granularity,

    38                                              size_t commit_factor,

    39                                              MemoryType type) :

    40   _storage(rs, used_size, page_size),

    41   _region_granularity(region_granularity),

    42   _listener(NULL),

    43   _commit_map(rs.size() * commit_factor / region_granularity, mtGC) {

    44   guarantee(is_power_of_2(page_size), "must be");

    45   guarantee(is_power_of_2(region_granularity), "must be");

    46 

    47   MemTracker::record_virtual_memory_type((address)rs.base(), type);

    48 }

    49 

    50 // G1RegionToSpaceMapper implementation where the region granularity is larger than

    51 // or the same as the commit granularity.

    52 // Basically, the space corresponding to one region region spans several OS pages.

    53 class G1RegionsLargerThanCommitSizeMapper : public G1RegionToSpaceMapper {

    54  private:

    55   size_t _pages_per_region;

    56 

    57  public:

    58   G1RegionsLargerThanCommitSizeMapper(ReservedSpace rs,

    59                                       size_t actual_size,

    60                                       size_t page_size,

    61                                       size_t alloc_granularity,

    62                                       size_t commit_factor,

    63                                       MemoryType type) :

    64     G1RegionToSpaceMapper(rs, actual_size, page_size, alloc_granularity, commit_factor, type),

    65     _pages_per_region(alloc_granularity / (page_size * commit_factor)) {

    66 

    67     guarantee(alloc_granularity >= page_size, "allocation granularity smaller than commit granularity");

    68   }

    69 

    70   virtual void commit_regions(uint start_idx, size_t num_regions, WorkGang* pretouch_gang) {

    71     size_t const start_page = (size_t)start_idx * _pages_per_region;

    72     bool zero_filled = _storage.commit(start_page, num_regions * _pages_per_region);

    73     if (AlwaysPreTouch) {

    74       _storage.pretouch(start_page, num_regions * _pages_per_region, pretouch_gang);

    75     }

    76     _commit_map.set_range(start_idx, start_idx + num_regions);

    77     fire_on_commit(start_idx, num_regions, zero_filled);

    78   }

    79 

    80   virtual void uncommit_regions(uint start_idx, size_t num_regions) {

    81     _storage.uncommit((size_t)start_idx * _pages_per_region, num_regions * _pages_per_region);

    82     _commit_map.clear_range(start_idx, start_idx + num_regions);

    83   }

    84 };

    85 

    86 // G1RegionToSpaceMapper implementation where the region granularity is smaller

    87 // than the commit granularity.

    88 // Basically, the contents of one OS page span several regions.

    89 class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {

    90  private:

    91   class CommitRefcountArray : public G1BiasedMappedArray<uint> {

    92    protected:

    93      virtual uint default_value() const { return 0; }

    94   };

    95 

    96   size_t _regions_per_page;

    97 

    98   CommitRefcountArray _refcounts;

    99 

   100   uintptr_t region_idx_to_page_idx(uint region) const {

   101     return region / _regions_per_page;

   102   }

   103 

   104  public:

   105   G1RegionsSmallerThanCommitSizeMapper(ReservedSpace rs,

   106                                        size_t actual_size,

   107                                        size_t page_size,

   108                                        size_t alloc_granularity,

   109                                        size_t commit_factor,

   110                                        MemoryType type) :

   111     G1RegionToSpaceMapper(rs, actual_size, page_size, alloc_granularity, commit_factor, type),

   112     _regions_per_page((page_size * commit_factor) / alloc_granularity), _refcounts() {

   113 

   114     guarantee((page_size * commit_factor) >= alloc_granularity, "allocation granularity smaller than commit granularity");

   115     _refcounts.initialize((HeapWord*)rs.base(), (HeapWord*)(rs.base() + align_up(rs.size(), page_size)), page_size);

   116   }

   117 

   118   virtual void commit_regions(uint start_idx, size_t num_regions, WorkGang* pretouch_gang) {

   119     size_t const NoPage = ~(size_t)0;

   120 

   121     size_t first_committed = NoPage;

   122     size_t num_committed = 0;

   123 

   124     bool all_zero_filled = true;

   125 

   126     for (uint i = start_idx; i < start_idx + num_regions; i++) {

   127       assert(!_commit_map.at(i), "Trying to commit storage at region %u that is already committed", i);

   128       size_t idx = region_idx_to_page_idx(i);

   129       uint old_refcount = _refcounts.get_by_index(idx);

   130 

   131       bool zero_filled = false;

   132       if (old_refcount == 0) {

   133         if (first_committed == NoPage) {

   134           first_committed = idx;

   135           num_committed = 1;

   136         } else {

   137           num_committed++;

   138         }

   139         zero_filled = _storage.commit(idx, 1);

   140       }

   141       all_zero_filled &= zero_filled;

   142 

   143       _refcounts.set_by_index(idx, old_refcount + 1);

   144       _commit_map.set_bit(i);

   145     }

   146     if (AlwaysPreTouch && num_committed > 0) {

   147       _storage.pretouch(first_committed, num_committed, pretouch_gang);

   148     }

   149     fire_on_commit(start_idx, num_regions, all_zero_filled);

   150   }

   151 

   152   virtual void uncommit_regions(uint start_idx, size_t num_regions) {

   153     for (uint i = start_idx; i < start_idx + num_regions; i++) {

   154       assert(_commit_map.at(i), "Trying to uncommit storage at region %u that is not committed", i);

   155       size_t idx = region_idx_to_page_idx(i);

   156       uint old_refcount = _refcounts.get_by_index(idx);

   157       assert(old_refcount > 0, "must be");

   158       if (old_refcount == 1) {

   159         _storage.uncommit(idx, 1);

   160       }

   161       _refcounts.set_by_index(idx, old_refcount - 1);

   162       _commit_map.clear_bit(i);

   163     }

   164   }

   165 };

   166 

   167 void G1RegionToSpaceMapper::fire_on_commit(uint start_idx, size_t num_regions, bool zero_filled) {

   168   if (_listener != NULL) {

   169     _listener->on_commit(start_idx, num_regions, zero_filled);

   170   }

   171 }

   172 

   173 G1RegionToSpaceMapper* G1RegionToSpaceMapper::create_mapper(ReservedSpace rs,

   174                                                             size_t actual_size,

   175                                                             size_t page_size,

   176                                                             size_t region_granularity,

   177                                                             size_t commit_factor,

   178                                                             MemoryType type) {

   179 

   180   if (region_granularity >= (page_size * commit_factor)) {

   181     return new G1RegionsLargerThanCommitSizeMapper(rs, actual_size, page_size, region_granularity, commit_factor, type);

   182   } else {

   183     return new G1RegionsSmallerThanCommitSizeMapper(rs, actual_size, page_size, region_granularity, commit_factor, type);

   184   }

   185 }