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   // After a region is allocated by alloc_new_region, this
  84   // method is used to set it as the active alloc_region
  85   void update_alloc_region(HeapRegion* alloc_region);
  86 
  87   // Allocate a new active region and use it to perform a word_size
  88   // allocation. The force parameter will be passed on to
  89   // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
  90   // to allocate a new region even if the max has been reached.
  91   HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
  92 
  93 protected:
  94   // Reset the alloc region to point a the dummy region.
  95   void reset_alloc_region();
  96 
  97   // Perform a non-MT-safe allocation out of the given region.
  98   inline HeapWord* allocate(HeapRegion* alloc_region,
  99                             size_t word_size);
 100 
 101   // Perform a MT-safe allocation out of the given region.
 102   inline HeapWord* par_allocate(HeapRegion* alloc_region,
 103                                 size_t word_size);
 104   // Perform a MT-safe allocation out of the given region, with the given
 105   // minimum and desired size. Returns the actual size allocated (between
 106   // minimum and desired size) in actual_word_size if the allocation has been
 107   // successful.
 108   inline HeapWord* par_allocate(HeapRegion* alloc_region,
 109                                 size_t min_word_size,
 110                                 size_t desired_word_size,
 111                                 size_t* actual_word_size);
 112 
 113   // Ensure that the region passed as a parameter has been filled up
 114   // so that noone else can allocate out of it any more.
 115   // Returns the number of bytes that have been wasted by filled up
 116   // the space.
 117   size_t fill_up_remaining_space(HeapRegion* alloc_region);
 118 











 119   // Retire the active allocating region. If fill_up is true then make
 120   // sure that the region is full before we retire it so that no one
 121   // else can allocate out of it.
 122   // Returns the number of bytes that have been filled up during retire.
 123   virtual size_t retire(bool fill_up);
 124 
 125   size_t retire_internal(HeapRegion* alloc_region, bool fill_up);
 126 
 127   // For convenience as subclasses use it.
 128   static G1CollectedHeap* _g1h;
 129 
 130   virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
 131   virtual void retire_region(HeapRegion* alloc_region,
 132                              size_t allocated_bytes) = 0;
 133 
 134   G1AllocRegion(const char* name, bool bot_updates);
 135 
 136 public:
 137   static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
 138 
 139   HeapRegion* get() const {
 140     HeapRegion * hr = _alloc_region;
 141     // Make sure that the dummy region does not escape this class.
 142     return (hr == _dummy_region) ? NULL : hr;
 143   }
 144 
 145   uint count() { return _count; }
 146 
 147   // The following two are the building blocks for the allocation method.
 148 
 149   // First-level allocation: Should be called without holding a
 150   // lock. It will try to allocate lock-free out of the active region,
 151   // or return NULL if it was unable to.
 152   inline HeapWord* attempt_allocation(size_t word_size);
 153   // Perform an allocation out of the current allocation region, with the given
 154   // minimum and desired size. Returns the actual size allocated (between
 155   // minimum and desired size) in actual_word_size if the allocation has been
 156   // successful.
 157   // Should be called without holding a lock. It will try to allocate lock-free
 158   // out of the active region, or return NULL if it was unable to.
 159   inline HeapWord* attempt_allocation(size_t min_word_size,
 160                                       size_t desired_word_size,
 161                                       size_t* actual_word_size);
 162 
 163   // Second-level allocation: Should be called while holding a
 164   // lock. It will try to first allocate lock-free out of the active
 165   // region or, if it's unable to, it will try to replace the active
 166   // alloc region with a new one. We require that the caller takes the
 167   // appropriate lock before calling this so that it is easier to make
 168   // it conform to its locking protocol.
 169   inline HeapWord* attempt_allocation_locked(size_t word_size);
 170   // Same as attempt_allocation_locked(size_t, bool), but allowing specification
 171   // of minimum word size of the block in min_word_size, and the maximum word
 172   // size of the allocation in desired_word_size. The actual size of the block is
 173   // returned in actual_word_size.
 174   inline HeapWord* attempt_allocation_locked(size_t min_word_size,
 175                                              size_t desired_word_size,
 176                                              size_t* actual_word_size);
 177 
 178   // Should be called to allocate a new region even if the max of this
 179   // type of regions has been reached. Should only be called if other
 180   // allocation attempts have failed and we are not holding a valid
 181   // active region.
 182   inline HeapWord* attempt_allocation_force(size_t word_size);
 183 
 184   // Should be called before we start using this object.
 185   virtual void init();
 186 
 187   // This can be used to set the active region to a specific
 188   // region. (Use Example: we try to retain the last old GC alloc
 189   // region that we've used during a GC and we can use set() to
 190   // re-instate it at the beginning of the next GC.)
 191   void set(HeapRegion* alloc_region);
 192 
 193   // Should be called when we want to release the active region which
 194   // is returned after it's been retired.
 195   virtual HeapRegion* release();
 196 
 197   void trace(const char* str,
 198              size_t min_word_size = 0,
 199              size_t desired_word_size = 0,
 200              size_t actual_word_size = 0,
 201              HeapWord* result = NULL) PRODUCT_RETURN;
 202 };
 203 
 204 class MutatorAllocRegion : public G1AllocRegion {
 205 private:
 206   // Keeps track of the total waste generated during the current
 207   // mutator phase.
 208   size_t _wasted_bytes;
 209 
 210   // Retained allocation region. Used to lower the waste generated
 211   // during mutation by having two active regions if the free space
 212   // in a region about to be retired still could fit a TLAB.
 213   HeapRegion* volatile _retained_alloc_region;
 214 
 215   // Decide if the region should be retained, based on the free size
 216   // in it and the free size in the currently retained region, if any.
 217   bool should_retain(HeapRegion* region);
 218 protected:
 219   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 220   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 221   virtual size_t retire(bool fill_up);
 222 public:
 223   MutatorAllocRegion()
 224     : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */),
 225       _wasted_bytes(0),
 226       _retained_alloc_region(NULL) { }
 227 
 228   // Returns the combined used memory in the current alloc region and
 229   // the retained alloc region.
 230   size_t used_in_alloc_regions();
 231 
 232   // Perform an allocation out of the retained allocation region, with the given
 233   // minimum and desired size. Returns the actual size allocated (between
 234   // minimum and desired size) in actual_word_size if the allocation has been
 235   // successful.
 236   // Should be called without holding a lock. It will try to allocate lock-free
 237   // out of the retained region, or return NULL if it was unable to.
 238   inline HeapWord* attempt_retained_allocation(size_t min_word_size,
 239                                                size_t desired_word_size,
 240                                                size_t* actual_word_size);
 241 
 242   // This specialization of release() makes sure that the retained alloc
 243   // region is retired and set to NULL.
 244   virtual HeapRegion* release();
 245 
 246   virtual void init();
 247 };
 248 // Common base class for allocation regions used during GC.
 249 class G1GCAllocRegion : public G1AllocRegion {
 250 protected:
 251   G1EvacStats* _stats;
 252   InCSetState::in_cset_state_t _purpose;
 253 
 254   virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
 255   virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
 256 
 257   virtual size_t retire(bool fill_up);
 258 
 259   G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose)
 260   : G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
 261     assert(stats != NULL, "Must pass non-NULL PLAB statistics");
 262   }
 263 };
 264 
 265 class SurvivorGCAllocRegion : public G1GCAllocRegion {
 266 public:
 267   SurvivorGCAllocRegion(G1EvacStats* stats)
 268   : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { }
 269 };
 270 
 271 class OldGCAllocRegion : public G1GCAllocRegion {
 272 public:
 273   OldGCAllocRegion(G1EvacStats* stats)
 274   : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { }
 275 
 276   // This specialization of release() makes sure that the last card that has
 277   // been allocated into has been completely filled by a dummy object.  This
 278   // avoids races when remembered set scanning wants to update the BOT of the
 279   // last card in the retained old gc alloc region, and allocation threads
 280   // allocating into that card at the same time.
 281   virtual HeapRegion* release();
 282 };
 283 
 284 #endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP
--- EOF ---