/*

 * 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

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 */

#include "gc/parallel/mutableSpace.hpp"

#include "gc/shared/gcUtil.hpp"

#include "utilities/macros.hpp"

/*

 *    The NUMA-aware allocator (MutableNUMASpace) is basically a modification

 * of MutableSpace which preserves interfaces but implements different

 * functionality. The space is split into chunks for each locality group

 * (resizing for adaptive size policy is also supported). For each thread

 * allocations are performed in the chunk corresponding to the home locality

 * group of the thread. Whenever any chunk fills-in the young generation

 * collection occurs.

 *   The chunks can be also be adaptively resized. The idea behind the adaptive

 * sizing is to reduce the loss of the space in the eden due to fragmentation.

 * The main cause of fragmentation is uneven allocation rates of threads.

 * The allocation rate difference between locality groups may be caused either by

 * application specifics or by uneven LWP distribution by the OS. Besides,

 * application can have less threads then the number of locality groups.

 * In order to resize the chunk we measure the allocation rate of the

 * application between collections. After that we reshape the chunks to reflect

 * the allocation rate pattern. The AdaptiveWeightedAverage exponentially

 * decaying average is used to smooth the measurements. The NUMASpaceResizeRate

 * parameter is used to control the adaptation speed by restricting the number of

 * bytes that can be moved during the adaptation phase.

 *   Chunks may contain pages from a wrong locality group. The page-scanner has

 * been introduced to address the problem. Remote pages typically appear due to

 * the memory shortage in the target locality group. Besides Solaris would

 * allocate a large page from the remote locality group even if there are small

 * local pages available. The page-scanner scans the pages right after the

 * collection and frees remote pages in hope that subsequent reallocation would

 * be more successful. This approach proved to be useful on systems with high

 * load where multiple processes are competing for the memory.

 */

class MutableNUMASpace : public MutableSpace {

  friend class VMStructs;

  class LGRPSpace : public CHeapObj<mtGC> {

    int _lgrp_id;

    MutableSpace* _space;

    MemRegion _invalid_region;

    AdaptiveWeightedAverage *_alloc_rate;

    bool _allocation_failed;

    struct SpaceStats {

      size_t _local_space, _remote_space, _unbiased_space, _uncommited_space;

      size_t _large_pages, _small_pages;

      SpaceStats() {

        _local_space = 0;

        _remote_space = 0;

        _unbiased_space = 0;

        _uncommited_space = 0;

        _large_pages = 0;

        _small_pages = 0;

      }

    };

    SpaceStats _space_stats;

    char* _last_page_scanned;

    char* last_page_scanned()            { return _last_page_scanned; }

    void set_last_page_scanned(char* p)  { _last_page_scanned = p;    }

   public:

    LGRPSpace(int l, size_t alignment) : _lgrp_id(l), _allocation_failed(false), _last_page_scanned(NULL) {

      _space = new MutableSpace(alignment);

      _alloc_rate = new AdaptiveWeightedAverage(NUMAChunkResizeWeight);

    }

    ~LGRPSpace() {

      delete _space;

      delete _alloc_rate;

    }

    void add_invalid_region(MemRegion r) {

      if (!_invalid_region.is_empty()) {

      _invalid_region.set_start(MIN2(_invalid_region.start(), r.start()));

      _invalid_region.set_end(MAX2(_invalid_region.end(), r.end()));

      } else {

      _invalid_region = r;

      }

    }

    static bool equals(void* lgrp_id_value, LGRPSpace* p) {

      return *(int*)lgrp_id_value == p->lgrp_id();

    }

    // Report a failed allocation.

    void set_allocation_failed() { _allocation_failed = true;  }

    void sample() {

      // If there was a failed allocation make allocation rate equal

      // to the size of the whole chunk. This ensures the progress of

      // the adaptation process.

      size_t alloc_rate_sample;

      if (_allocation_failed) {

        alloc_rate_sample = space()->capacity_in_bytes();

        _allocation_failed = false;

      } else {

        alloc_rate_sample = space()->used_in_bytes();

      }

      alloc_rate()->sample(alloc_rate_sample);

    }

    MemRegion invalid_region() const                { return _invalid_region;      }

    void set_invalid_region(MemRegion r)            { _invalid_region = r;         }

    int lgrp_id() const                             { return _lgrp_id;             }

    MutableSpace* space() const                     { return _space;               }

    AdaptiveWeightedAverage* alloc_rate() const     { return _alloc_rate;          }

    void clear_alloc_rate()                         { _alloc_rate->clear();        }

    SpaceStats* space_stats()                       { return &_space_stats;        }

    void clear_space_stats()                        { _space_stats = SpaceStats(); }

    void accumulate_statistics(size_t page_size);

    void scan_pages(size_t page_size, size_t page_count);

  };

  GrowableArray<LGRPSpace*>* _lgrp_spaces;

  size_t _page_size;

  unsigned _adaptation_cycles, _samples_count;

  bool _must_use_large_pages;

  void set_page_size(size_t psz)                     { _page_size = psz;          }

  size_t page_size() const                           { return _page_size;         }

  unsigned adaptation_cycles()                       { return _adaptation_cycles; }

  void set_adaptation_cycles(int v)                  { _adaptation_cycles = v;    }

  unsigned samples_count()                           { return _samples_count;     }

  void increment_samples_count()                     { ++_samples_count;          }

  size_t _base_space_size;

  void set_base_space_size(size_t v)                 { _base_space_size = v;      }

  size_t base_space_size() const                     { return _base_space_size;   }

  // Check if the NUMA topology has changed. Add and remove spaces if needed.

  // The update can be forced by setting the force parameter equal to true.

  bool update_layout(bool force);

  // Bias region towards the lgrp.

  void bias_region(MemRegion mr, int lgrp_id);

  // Free pages in a given region.

  void free_region(MemRegion mr);

  // Get current chunk size.

  size_t current_chunk_size(int i);

  // Get default chunk size (equally divide the space).

  size_t default_chunk_size();

  // Adapt the chunk size to follow the allocation rate.

  size_t adaptive_chunk_size(int i, size_t limit);

  // Scan and free invalid pages.

  void scan_pages(size_t page_count);

  // Return the bottom_region and the top_region. Align them to page_size() boundary.

  // |------------------new_region---------------------------------|

  // |----bottom_region--|---intersection---|------top_region------|

  void select_tails(MemRegion new_region, MemRegion intersection,

                    MemRegion* bottom_region, MemRegion *top_region);

  // Try to merge the invalid region with the bottom or top region by decreasing

  // the intersection area. Return the invalid_region aligned to the page_size()

  // boundary if it's inside the intersection. Return non-empty invalid_region

  // if it lies inside the intersection (also page-aligned).

  // |------------------new_region---------------------------------|

  // |----------------|-------invalid---|--------------------------|

  // |----bottom_region--|---intersection---|------top_region------|

  void merge_regions(MemRegion new_region, MemRegion* intersection,

                     MemRegion *invalid_region);

 public:

  GrowableArray<LGRPSpace*>* lgrp_spaces() const     { return _lgrp_spaces;       }

  MutableNUMASpace(size_t alignment);

  virtual ~MutableNUMASpace();

  // Space initialization.

  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space, bool setup_pages = SetupPages);

  // Update space layout if necessary. Do all adaptive resizing job.

  virtual void update();

  // Update allocation rate averages.

  virtual void accumulate_statistics();

  virtual void clear(bool mangle_space);

  virtual void mangle_unused_area() PRODUCT_RETURN;

  virtual void mangle_unused_area_complete() PRODUCT_RETURN;

  virtual void mangle_region(MemRegion mr) PRODUCT_RETURN;

  virtual void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;

  virtual void check_mangled_unused_area_complete() PRODUCT_RETURN;

  virtual void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;

  virtual void set_top_for_allocations() PRODUCT_RETURN;

  virtual void ensure_parsability();

  virtual size_t used_in_words() const;

  virtual size_t free_in_words() const;

  using MutableSpace::capacity_in_words;

  virtual size_t capacity_in_words(Thread* thr) const;

  virtual size_t tlab_capacity(Thread* thr) const;

  virtual size_t tlab_used(Thread* thr) const;

  virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;

  // Allocation (return NULL if full)

  virtual HeapWord* allocate(size_t word_size);

  virtual HeapWord* cas_allocate(size_t word_size);

  // Debugging

  virtual void print_on(outputStream* st) const;

  virtual void print_short_on(outputStream* st) const;

  virtual void verify();

  virtual void set_top(HeapWord* value);

};