rev 7799 : imported patch 8073466-remove-ratining-functionality-in-pargcallocbuffer

   1 /*
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   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
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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_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
  27 #include "gc_interface/collectedHeap.hpp"

  28 #include "memory/allocation.hpp"
  29 #include "memory/blockOffsetTable.hpp"
  30 #include "memory/threadLocalAllocBuffer.hpp"
  31 #include "utilities/globalDefinitions.hpp"
  32 
  33 // Forward decl.
  34 
  35 class PLABStats;
  36 
  37 // A per-thread allocation buffer used during GC.
  38 class ParGCAllocBuffer: public CHeapObj<mtGC> {
  39 protected:
  40   char head[32];
  41   size_t _word_sz;          // in HeapWord units
  42   HeapWord* _bottom;
  43   HeapWord* _top;
  44   HeapWord* _end;       // last allocatable address + 1
  45   HeapWord* _hard_end;  // _end + AlignmentReserve
  46   bool      _retained;  // whether we hold a _retained_filler
  47   MemRegion _retained_filler;
  48   // In support of ergonomic sizing of PLAB's
  49   size_t    _allocated;     // in HeapWord units
  50   size_t    _wasted;        // in HeapWord units
  51   char tail[32];
  52   static size_t FillerHeaderSize;
  53   static size_t AlignmentReserve;
  54 
  55   // Flush the stats supporting ergonomic sizing of PLAB's
  56   // Should not be called directly
  57   void flush_stats(PLABStats* stats);
  58 
  59 public:
  60   // Initializes the buffer to be empty, but with the given "word_sz".
  61   // Must get initialized with "set_buf" for an allocation to succeed.
  62   ParGCAllocBuffer(size_t word_sz);
  63   virtual ~ParGCAllocBuffer() {}
  64 
  65   static const size_t min_size() {
  66     // Make sure that we return something that is larger than AlignmentReserve
  67     return align_object_size(MAX2(MinTLABSize / HeapWordSize, (uintx)oopDesc::header_size())) + AlignmentReserve;
  68   }
  69 
  70   static const size_t max_size() {
  71     return ThreadLocalAllocBuffer::max_size();
  72   }
  73 
  74   // If an allocation of the given "word_sz" can be satisfied within the
  75   // buffer, do the allocation, returning a pointer to the start of the
  76   // allocated block.  If the allocation request cannot be satisfied,
  77   // return NULL.
  78   HeapWord* allocate(size_t word_sz) {
  79     HeapWord* res = _top;
  80     if (pointer_delta(_end, _top) >= word_sz) {
  81       _top = _top + word_sz;
  82       return res;
  83     } else {
  84       return NULL;
  85     }
  86   }
  87 
  88   // Allocate the object aligned to "alignment_in_bytes".
  89   HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
  90 
  91   // Undo the last allocation in the buffer, which is required to be of the
  92   // "obj" of the given "word_sz".
  93   void undo_allocation(HeapWord* obj, size_t word_sz) {
  94     assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
  95     assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
  96     _top = obj;
  97   }
  98 
  99   // The total (word) size of the buffer, including both allocated and
 100   // unallocated space.
 101   size_t word_sz() { return _word_sz; }
 102 
 103   // Should only be done if we are about to reset with a new buffer of the
 104   // given size.
 105   void set_word_size(size_t new_word_sz) {
 106     assert(new_word_sz > AlignmentReserve, "Too small");
 107     _word_sz = new_word_sz;
 108   }
 109 
 110   // The number of words of unallocated space remaining in the buffer.
 111   size_t words_remaining() {
 112     assert(_end >= _top, "Negative buffer");
 113     return pointer_delta(_end, _top, HeapWordSize);
 114   }
 115 
 116   bool contains(void* addr) {
 117     return (void*)_bottom <= addr && addr < (void*)_hard_end;
 118   }
 119 
 120   // Sets the space of the buffer to be [buf, space+word_sz()).
 121   virtual void set_buf(HeapWord* buf) {
 122     _bottom   = buf;
 123     _top      = _bottom;
 124     _hard_end = _bottom + word_sz();
 125     _end      = _hard_end - AlignmentReserve;
 126     assert(_end >= _top, "Negative buffer");
 127     // In support of ergonomic sizing
 128     _allocated += word_sz();
 129   }
 130 
 131   // Flush the stats supporting ergonomic sizing of PLAB's
 132   // and retire the current buffer.
 133   void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
 134     // We flush the stats first in order to get a reading of
 135     // unused space in the last buffer.
 136     if (ResizePLAB) {
 137       flush_stats(stats);
 138 
 139       // Since we have flushed the stats we need to clear
 140       // the _allocated and _wasted fields. Not doing so
 141       // will artifically inflate the values in the stats
 142       // to which we add them.
 143       // The next time we flush these values, we will add
 144       // what we have just flushed in addition to the size
 145       // of the buffers allocated between now and then.
 146       _allocated = 0;
 147       _wasted = 0;
 148     }
 149     // Retire the last allocation buffer.
 150     retire(end_of_gc, retain);
 151   }
 152 
 153   // Force future allocations to fail and queries for contains()
 154   // to return false
 155   void invalidate() {
 156     assert(!_retained, "Shouldn't retain an invalidated buffer.");
 157     _end    = _hard_end;
 158     _wasted += pointer_delta(_end, _top);  // unused  space
 159     _top    = _end;      // force future allocations to fail
 160     _bottom = _end;      // force future contains() queries to return false
 161   }
 162 
 163   // Fills in the unallocated portion of the buffer with a garbage object.
 164   // If "end_of_gc" is TRUE, is after the last use in the GC.  IF "retain"
 165   // is true, attempt to re-use the unused portion in the next GC.
 166   virtual void retire(bool end_of_gc, bool retain);
 167 
 168   void print() PRODUCT_RETURN;
 169 };
 170 
 171 // PLAB stats book-keeping
 172 class PLABStats VALUE_OBJ_CLASS_SPEC {
 173   size_t _allocated;      // total allocated
 174   size_t _wasted;         // of which wasted (internal fragmentation)
 175   size_t _unused;         // Unused in last buffer
 176   size_t _used;           // derived = allocated - wasted - unused
 177   size_t _desired_plab_sz;// output of filter (below), suitably trimmed and quantized
 178   AdaptiveWeightedAverage
 179          _filter;         // integrator with decay
 180 





 181  public:
 182   PLABStats(size_t desired_plab_sz_, unsigned wt) :
 183     _allocated(0),
 184     _wasted(0),
 185     _unused(0),
 186     _used(0),
 187     _desired_plab_sz(desired_plab_sz_),
 188     _filter(wt)
 189   { }
 190 
 191   static const size_t min_size() {
 192     return ParGCAllocBuffer::min_size();
 193   }
 194 
 195   static const size_t max_size() {
 196     return ParGCAllocBuffer::max_size();
 197   }
 198 
 199   size_t desired_plab_sz() {
 200     return _desired_plab_sz;
 201   }
 202 


 203   void adjust_desired_plab_sz(uint no_of_gc_workers);
 204                                  // filter computation, latches output to
 205                                  // _desired_plab_sz, clears sensor accumulators
 206 
 207   void add_allocated(size_t v) {
 208     Atomic::add_ptr(v, &_allocated);
 209   }
 210 
 211   void add_unused(size_t v) {
 212     Atomic::add_ptr(v, &_unused);
 213   }
 214 
 215   void add_wasted(size_t v) {
 216     Atomic::add_ptr(v, &_wasted);
 217   }
 218 };
 219 
 220 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
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