rev 49850 : imported patch 8191471-region-logging-waste
rev 49852 : imported patch 8191471-g1-retained-mutator-region
rev 49854 : [mq]: 8191471-tschatzl-comments-move-wasted

   1 /*
   2  * Copyright (c) 2011, 2018, 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_G1_G1ALLOCREGION_HPP
  26 #define SHARE_VM_GC_G1_G1ALLOCREGION_HPP
  27 
  28 #include "gc/g1/heapRegion.hpp"
  29 #include "gc/g1/g1EvacStats.hpp"
  30 #include "gc/g1/g1InCSetState.hpp"
  31 
  32 class G1CollectedHeap;
  33 
  34 // A class that holds a region that is active in satisfying allocation
  35 // requests, potentially issued in parallel. When the active region is
  36 // full it will be retired and replaced with a new one. The
  37 // implementation assumes that fast-path allocations will be lock-free
  38 // and a lock will need to be taken when the active region needs to be
  39 // replaced.
  40 
  41 class G1AllocRegion {
  42 
  43 private:
  44   // The active allocating region we are currently allocating out
  45   // of. The invariant is that if this object is initialized (i.e.,
  46   // init() has been called and release() has not) then _alloc_region
  47   // is either an active allocating region or the dummy region (i.e.,
  48   // it can never be NULL) and this object can be used to satisfy
  49   // allocation requests. If this object is not initialized
  50   // (i.e. init() has not been called or release() has been called)
  51   // then _alloc_region is NULL and this object should not be used to
  52   // satisfy allocation requests (it was done this way to force the
  53   // correct use of init() and release()).
  54   HeapRegion* volatile _alloc_region;
  55 
  56   // It keeps track of the distinct number of regions that are used
  57   // for allocation in the active interval of this object, i.e.,
  58   // between a call to init() and a call to release(). The count
  59   // mostly includes regions that are freshly allocated, as well as
  60   // the region that is re-used using the set() method. This count can
  61   // be used in any heuristics that might want to bound how many
  62   // distinct regions this object can used during an active interval.
  63   uint _count;
  64 
  65   // When we set up a new active region we save its used bytes in this
  66   // field so that, when we retire it, we can calculate how much space
  67   // we allocated in it.
  68   size_t _used_bytes_before;
  69 
  70   // When true, indicates that allocate calls should do BOT updates.
  71   const bool _bot_updates;
  72 
  73   // Useful for debugging and tracing.
  74   const char* _name;
  75 
  76   // A dummy region (i.e., it's been allocated specially for this
  77   // purpose and it is not part of the heap) that is full (i.e., top()
  78   // == end()). When we don't have a valid active region we make
  79   // _alloc_region point to this. This allows us to skip checking
  80   // whether the _alloc_region is NULL or not.
  81   static HeapRegion* _dummy_region;
  82 














  83   // Perform a non-MT-safe allocation out of the given region.
  84   inline HeapWord* allocate(HeapRegion* alloc_region,
  85                             size_t word_size);
  86 
  87   // Perform a MT-safe allocation out of the given region.
  88   inline HeapWord* par_allocate(HeapRegion* alloc_region,
  89                                 size_t word_size);
  90   // Perform a MT-safe allocation out of the given region, with the given
  91   // minimum and desired size. Returns the actual size allocated (between
  92   // minimum and desired size) in actual_word_size if the allocation has been
  93   // successful.
  94   inline HeapWord* par_allocate(HeapRegion* alloc_region,
  95                                 size_t min_word_size,
  96                                 size_t desired_word_size,
  97                                 size_t* actual_word_size);
  98 
  99   // Ensure that the region passed as a parameter has been filled up
 100   // so that noone else can allocate out of it any more.
 101   // Returns the number of bytes that have been wasted by filled up
 102   // the space.
 103   size_t fill_up_remaining_space(HeapRegion* alloc_region);
 104 
 105   // After a region is allocated by alloc_new_region, this
 106   // method is used to set it as the active alloc_region
 107   void update_alloc_region(HeapRegion* alloc_region);
 108 
 109   // Allocate a new active region and use it to perform a word_size
 110   // allocation. The force parameter will be passed on to
 111   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
 112   // to allocate a new region even if the max has been reached.
 113   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
 114 
 115 protected:
 116   // Retire the active allocating region. If fill_up is true then make
 117   // sure that the region is full before we retire it so that no one
 118   // else can allocate out of it.
 119   // Returns the number of bytes that have been filled up during retire.
 120   virtual size_t retire(bool fill_up);
 121 


 122   // For convenience as subclasses use it.
 123   static G1CollectedHeap* _g1h;
 124 
 125   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
 126   virtual void retire_region(HeapRegion* alloc_region,
 127                              size_t allocated_bytes) = 0;
 128 
 129   G1AllocRegion(const char* name, bool bot_updates);
 130 
 131 public:
 132   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
 133 
 134   HeapRegion* get() const {
 135     HeapRegion * hr = _alloc_region;
 136     // Make sure that the dummy region does not escape this class.
 137     return (hr == _dummy_region) ? NULL : hr;
 138   }
 139 
 140   uint count() { return _count; }
 141 
 142   // The following two are the building blocks for the allocation method.
 143 
 144   // First-level allocation: Should be called without holding a
 145   // lock. It will try to allocate lock-free out of the active region,
 146   // or return NULL if it was unable to.
 147   inline HeapWord* attempt_allocation(size_t word_size);
 148   // Perform an allocation out of the current allocation region, with the given
 149   // minimum and desired size. Returns the actual size allocated (between
 150   // minimum and desired size) in actual_word_size if the allocation has been
 151   // successful.
 152   // Should be called without holding a lock. It will try to allocate lock-free
 153   // out of the active region, or return NULL if it was unable to.
 154   inline HeapWord* attempt_allocation(size_t min_word_size,
 155                                       size_t desired_word_size,
 156                                       size_t* actual_word_size);
 157 
 158   // Second-level allocation: Should be called while holding a
 159   // lock. It will try to first allocate lock-free out of the active
 160   // region or, if it's unable to, it will try to replace the active
 161   // alloc region with a new one. We require that the caller takes the
 162   // appropriate lock before calling this so that it is easier to make
 163   // it conform to its locking protocol.
 164   inline HeapWord* attempt_allocation_locked(size_t word_size);
 165   // Same as attempt_allocation_locked(size_t, bool), but allowing specification
 166   // of minimum word size of the block in min_word_size, and the maximum word
 167   // size of the allocation in desired_word_size. The actual size of the block is
 168   // returned in actual_word_size.
 169   inline HeapWord* attempt_allocation_locked(size_t min_word_size,
 170                                              size_t desired_word_size,
 171                                              size_t* actual_word_size);
 172 
 173   // Should be called to allocate a new region even if the max of this
 174   // type of regions has been reached. Should only be called if other
 175   // allocation attempts have failed and we are not holding a valid
 176   // active region.
 177   inline HeapWord* attempt_allocation_force(size_t word_size);
 178 
 179   // Should be called before we start using this object.
 180   void init();
 181 
 182   // This can be used to set the active region to a specific
 183   // region. (Use Example: we try to retain the last old GC alloc
 184   // region that we've used during a GC and we can use set() to
 185   // re-instate it at the beginning of the next GC.)
 186   void set(HeapRegion* alloc_region);
 187 
 188   // Should be called when we want to release the active region which
 189   // is returned after it's been retired.
 190   virtual HeapRegion* release();
 191 
 192   void trace(const char* str,
 193              size_t min_word_size = 0,
 194              size_t desired_word_size = 0,
 195              size_t actual_word_size = 0,
 196              HeapWord* result = NULL) PRODUCT_RETURN;
 197 };
 198 
 199 class MutatorAllocRegion : public G1AllocRegion {













 200 protected:
 201   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 202   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);

 203 public:
 204   MutatorAllocRegion()
 205     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
 206 };



















 207 


 208 // Common base class for allocation regions used during GC.
 209 class G1GCAllocRegion : public G1AllocRegion {
 210 protected:
 211   G1EvacStats* _stats;
 212   InCSetState::in_cset_state_t _purpose;
 213 
 214   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 215   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 216 
 217   virtual size_t retire(bool fill_up);
 218 
 219   G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose)
 220   : G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
 221     assert(stats != NULL, "Must pass non-NULL PLAB statistics");
 222   }
 223 };
 224 
 225 class SurvivorGCAllocRegion : public G1GCAllocRegion {
 226 public:
 227   SurvivorGCAllocRegion(G1EvacStats* stats)
 228   : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { }
 229 };
 230 
 231 class OldGCAllocRegion : public G1GCAllocRegion {
 232 public:
 233   OldGCAllocRegion(G1EvacStats* stats)
 234   : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { }
 235 
 236   // This specialization of release() makes sure that the last card that has
 237   // been allocated into has been completely filled by a dummy object.  This
 238   // avoids races when remembered set scanning wants to update the BOT of the
 239   // last card in the retained old gc alloc region, and allocation threads
 240   // allocating into that card at the same time.
 241   virtual HeapRegion* release();
 242 };
 243 
 244 #endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP
--- EOF ---