1 /*
   2  * Copyright (c) 2014, 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.
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   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
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  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
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  24 
  25 #ifndef SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  26 #define SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  27 
  28 #include "memory/memRegion.hpp"
  29 #include "memory/virtualspace.hpp"
  30 #include "utilities/align.hpp"
  31 #include "utilities/bitMap.hpp"
  32 
  33 class G1NUMA;
  34 class WorkGang;
  35 
  36 // Virtual space management helper for a virtual space with an OS page allocation
  37 // granularity.
  38 // (De-)Allocation requests are always OS page aligned by passing a page index
  39 // and multiples of pages.
  40 // For systems that only commits of memory in a given size (always greater than
  41 // page size) the base address is required to be aligned to that page size.
  42 // The actual size requested need not be aligned to that page size, but the size
  43 // of the reservation passed may be rounded up to this page size. Any fragment
  44 // (less than the page size) of the actual size at the tail of the request will
  45 // be committed using OS small pages.
  46 // The implementation gives an error when trying to commit or uncommit pages that
  47 // have already been committed or uncommitted.
  48 class G1PageBasedVirtualSpace {
  49   friend class VMStructs;
  50  private:
  51   // Reserved area addresses.
  52   char* _low_boundary;
  53   char* _high_boundary;
  54 
  55   // The size of the tail in bytes of the handled space that needs to be committed
  56   // using small pages.
  57   size_t _tail_size;
  58 
  59   // The preferred page size used for commit/uncommit in bytes.
  60   size_t _page_size;
  61 
  62   // Bitmap used for verification of commit/uncommit operations.
  63   CHeapBitMap _committed;
  64 
  65   // Bitmap used to keep track of which pages are dirty or not for _special
  66   // spaces. This is needed because for those spaces the underlying memory
  67   // will only be zero filled the first time it is committed. Calls to commit
  68   // will use this bitmap and return whether or not the memory is zero filled.
  69   CHeapBitMap _dirty;
  70 
  71   // Indicates that the entire space has been committed and pinned in memory,
  72   // os::commit_memory() or os::uncommit_memory() have no function.
  73   bool _special;
  74 
  75   // Indicates whether the committed space should be executable.
  76   bool _executable;
  77 
  78   G1NUMA* _numa;
  79 
  80   // Helper function for committing memory. Commit the given memory range by using
  81   // _page_size pages as much as possible and the remainder with small sized pages.
  82   void commit_internal(size_t start_page, size_t end_page);
  83   // Commit num_pages pages of _page_size size starting from start. All argument
  84   // checking has been performed.
  85   void commit_preferred_pages(size_t start_page, size_t end_page);
  86   // Commit space at the high end of the space that needs to be committed with small
  87   // sized pages.
  88   void commit_tail();
  89 
  90   // Uncommit the given memory range.
  91   void uncommit_internal(size_t start_page, size_t end_page);
  92 
  93   // Pretouch the given memory range.
  94   void pretouch_internal(size_t start_page, size_t end_page);
  95 
  96   // Returns the index of the page which contains the given address.
  97   size_t  addr_to_page_index(char* addr) const;
  98   // Returns the address of the given page index.
  99   char*  page_start(size_t index) const;
 100 
 101   // Is the given page index the last page?
 102   bool is_last_page(size_t index) const { return index == (_committed.size() - 1); }
 103   // Is the given page index the first after last page?
 104   bool is_after_last_page(size_t index) const;
 105   // Is the last page only partially covered by this space?
 106   bool is_last_page_partial() const { return !is_aligned(_high_boundary, _page_size); }
 107   // Returns the end address of the given page bounded by the reserved space.
 108   char* bounded_end_addr(size_t end_page) const;
 109 
 110   // Returns true if the entire area is backed by committed memory.
 111   bool is_area_committed(size_t start_page, size_t size_in_pages) const;
 112   // Returns true if the entire area is not backed by committed memory.
 113   bool is_area_uncommitted(size_t start_page, size_t size_in_pages) const;
 114 
 115   void initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size, MemoryType type);
 116  public:
 117 
 118   // Commit the given area of pages starting at start being size_in_pages large.
 119   // Returns true if the given area is zero filled upon completion.
 120   virtual bool commit(size_t start_page, size_t size_in_pages, uint node_index);
 121 
 122   // Uncommit the given area of pages starting at start being size_in_pages large.
 123   virtual void uncommit(size_t start_page, size_t size_in_pages);
 124 
 125   virtual void pretouch(size_t start_page, size_t size_in_pages, WorkGang* pretouch_gang = NULL);
 126 
 127   // Initialize the given reserved space with the given base address and the size
 128   // actually used.
 129   // Prefer to commit in page_size chunks.
 130   G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size, MemoryType type);
 131 
 132   // Destruction
 133   ~G1PageBasedVirtualSpace();
 134 
 135   // Amount of reserved memory.
 136   size_t reserved_size() const;
 137   // Memory used in this virtual space.
 138   size_t committed_size() const;
 139   // Memory left to use/expand in this virtual space.
 140   size_t uncommitted_size() const;
 141 
 142   void commit_and_set_special();
 143 
 144   bool contains(const void* p) const;
 145 
 146   MemRegion reserved() {
 147     MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
 148     return x;
 149   }
 150 
 151   void check_for_contiguity() PRODUCT_RETURN;
 152 
 153   // Debugging
 154   void print_on(outputStream* out) PRODUCT_RETURN;
 155   void print();
 156 };
 157 
 158 #endif // SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP