rev 8852 : [mq]: 8133470-fix-plab-inline
rev 8853 : imported patch mikael-erik-suggestions
rev 8854 : imported patch 8073013-add-detailed-information-about-plab-memory-usage
rev 8857 : imported patch mikael-comments
rev 8866 : imported patch 8067339-PLAB-reallocation-might-result-in-failure-to-allocate
rev 8867 : [mq]: bengt-refactoring

   1 /*
   2  * Copyright (c) 2001, 2015, 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_SHARED_PLAB_HPP
  26 #define SHARE_VM_GC_SHARED_PLAB_HPP
  27 
  28 #include "gc/shared/gcUtil.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 // Forward declarations.
  33 class PLABStats;
  34 
  35 // A per-thread allocation buffer used during GC.
  36 class PLAB: public CHeapObj<mtGC> {
  37 protected:
  38   char      head[32];
  39   size_t    _word_sz;          // In HeapWord units
  40   HeapWord* _bottom;
  41   HeapWord* _top;
  42   HeapWord* _end;           // Last allocatable address + 1
  43   HeapWord* _hard_end;      // _end + AlignmentReserve
  44   // In support of ergonomic sizing of PLAB's
  45   size_t    _allocated;     // in HeapWord units
  46   size_t    _wasted;        // in HeapWord units
  47   size_t    _undo_wasted;
  48   char      tail[32];
  49   static size_t AlignmentReserve;
  50 
  51   // Force future allocations to fail and queries for contains()
  52   // to return false. Returns the amount of unused space in this PLAB.
  53   size_t invalidate() {
  54     _end    = _hard_end;
  55     size_t remaining = pointer_delta(_end, _top);  // Calculate remaining space.
  56     _top    = _end;      // Force future allocations to fail.
  57     _bottom = _end;      // Force future contains() queries to return false.
  58     return remaining;
  59   }
  60 
  61   // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
  62   // the amount of remaining space.
  63   size_t retire_internal();
  64 
  65   void add_undo_waste(HeapWord* obj, size_t word_sz);
  66 
  67   // Undo the last allocation in the buffer, which is required to be of the
  68   // "obj" of the given "word_sz".
  69   void undo_last_allocation(HeapWord* obj, size_t word_sz);
  70 
  71 public:
  72   // Initializes the buffer to be empty, but with the given "word_sz".
  73   // Must get initialized with "set_buf" for an allocation to succeed.
  74   PLAB(size_t word_sz);
  75   virtual ~PLAB() {}
  76 
  77   static size_t alignment_reserve() { return AlignmentReserve; }
  78 
  79   // Minimum PLAB size.
  80   static size_t min_size();
  81   // Maximum PLAB size.
  82   static size_t max_size();
  83 
  84   // If an allocation of the given "word_sz" can be satisfied within the
  85   // buffer, do the allocation, returning a pointer to the start of the
  86   // allocated block.  If the allocation request cannot be satisfied,
  87   // return NULL.
  88   HeapWord* allocate(size_t word_sz) {
  89     HeapWord* res = _top;
  90     if (pointer_delta(_end, _top) >= word_sz) {
  91       _top = _top + word_sz;
  92       return res;
  93     } else {
  94       return NULL;
  95     }
  96   }
  97 
  98   // Allocate the object aligned to "alignment_in_bytes".
  99   inline HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
 100 
 101   // Undo any allocation in the buffer, which is required to be of the
 102   // "obj" of the given "word_sz".
 103   void undo_allocation(HeapWord* obj, size_t word_sz);
 104 
 105   // The total (word) size of the buffer, including both allocated and
 106   // unallocated space.
 107   size_t word_sz() { return _word_sz; }
 108 
 109   size_t waste() { return _wasted; }
 110   size_t undo_waste() { return _undo_wasted; }
 111 
 112   // Should only be done if we are about to reset with a new buffer of the
 113   // given size.
 114   void set_word_size(size_t new_word_sz) {
 115     assert(new_word_sz > AlignmentReserve, "Too small");
 116     _word_sz = new_word_sz;
 117   }
 118 
 119   // The number of words of unallocated space remaining in the buffer.
 120   size_t words_remaining() {
 121     assert(_end >= _top, "Negative buffer");
 122     return pointer_delta(_end, _top, HeapWordSize);
 123   }
 124 
 125   bool contains(void* addr) {
 126     return (void*)_bottom <= addr && addr < (void*)_hard_end;
 127   }
 128 
 129   // Sets the space of the buffer to be [buf, space+word_sz()).
 130   virtual void set_buf(HeapWord* buf) {



 131     _bottom   = buf;
 132     _top      = _bottom;
 133     _hard_end = _bottom + word_sz();
 134     _end      = _hard_end - AlignmentReserve;
 135     assert(_end >= _top, "Negative buffer");
 136     // In support of ergonomic sizing
 137     _allocated += word_sz();
 138   }
 139 
 140   // Flush allocation statistics into the given PLABStats supporting ergonomic
 141   // sizing of PLAB's and retire the current buffer. To be called at the end of
 142   // GC.
 143   virtual void flush_and_retire_stats(PLABStats* stats);
 144 
 145   // Fills in the unallocated portion of the buffer with a garbage object and updates
 146   // statistics. To be called during GC.
 147   virtual void retire();
 148 
 149   void print() PRODUCT_RETURN;
 150 };
 151 
 152 // PLAB book-keeping.
 153 class PLABStats : public CHeapObj<mtGC> {
 154  protected:
 155   size_t _allocated;          // Total allocated
 156   size_t _wasted;             // of which wasted (internal fragmentation)
 157   size_t _undo_wasted;        // of which wasted on undo (is not used for calculation of PLAB size)
 158   size_t _unused;             // Unused in last buffer
 159   size_t _desired_net_plab_sz;// Output of filter (below), suitably trimmed and quantized
 160   AdaptiveWeightedAverage
 161          _filter;             // Integrator with decay
 162 
 163   virtual void reset() {
 164     _allocated   = 0;
 165     _wasted      = 0;
 166     _undo_wasted = 0;
 167     _unused      = 0;
 168   }
 169  public:
 170   PLABStats(size_t desired_net_plab_sz_, unsigned wt) :
 171     _allocated(0),
 172     _wasted(0),
 173     _undo_wasted(0),
 174     _unused(0),
 175     _desired_net_plab_sz(desired_net_plab_sz_),
 176     _filter(wt)
 177   { }
 178 
 179   virtual ~PLABStats() { }
 180 
 181   static const size_t min_size() {
 182     return PLAB::min_size();
 183   }
 184 
 185   static const size_t max_size() {
 186     return PLAB::max_size();
 187   }
 188 
 189   // Calculates plab size for current number of gc worker threads.
 190   size_t desired_plab_sz(uint no_of_gc_workers);
 191 
 192   // Updates the current desired PLAB size. Computes the new desired PLAB size with one gc worker thread,
 193   // updates _desired_plab_sz and clears sensor accumulators.
 194   virtual void adjust_desired_plab_sz();
 195 
 196   inline void add_allocated(size_t v);
 197 
 198   inline void add_unused(size_t v);
 199 
 200   inline void add_wasted(size_t v);
 201 
 202   inline void add_undo_wasted(size_t v);
 203 };
 204 
 205 #endif // SHARE_VM_GC_SHARED_PLAB_HPP
--- EOF ---