1 /* 2 * Copyright (c) 2011, 2019, 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_GC_G1_G1ALLOCREGION_HPP 26 #define SHARE_GC_G1_G1ALLOCREGION_HPP 27 28 #include "gc/g1/heapRegion.hpp" 29 #include "gc/g1/g1EvacStats.hpp" 30 #include "gc/g1/g1HeapRegionAttr.hpp" 31 #include "gc/g1/g1NUMA.hpp" 32 33 class G1CollectedHeap; 34 35 // A class that holds a region that is active in satisfying allocation 36 // requests, potentially issued in parallel. When the active region is 37 // full it will be retired and replaced with a new one. The 38 // implementation assumes that fast-path allocations will be lock-free 39 // and a lock will need to be taken when the active region needs to be 40 // replaced. 41 42 class G1AllocRegion : public CHeapObj<mtGC> { 43 44 private: 45 // The active allocating region we are currently allocating out 46 // of. The invariant is that if this object is initialized (i.e., 47 // init() has been called and release() has not) then _alloc_region 48 // is either an active allocating region or the dummy region (i.e., 49 // it can never be NULL) and this object can be used to satisfy 50 // allocation requests. If this object is not initialized 51 // (i.e. init() has not been called or release() has been called) 52 // then _alloc_region is NULL and this object should not be used to 53 // satisfy allocation requests (it was done this way to force the 54 // correct use of init() and release()). 55 HeapRegion* volatile _alloc_region; 56 57 // It keeps track of the distinct number of regions that are used 58 // for allocation in the active interval of this object, i.e., 59 // between a call to init() and a call to release(). The count 60 // mostly includes regions that are freshly allocated, as well as 61 // the region that is re-used using the set() method. This count can 62 // be used in any heuristics that might want to bound how many 63 // distinct regions this object can used during an active interval. 64 uint _count; 65 66 // When we set up a new active region we save its used bytes in this 67 // field so that, when we retire it, we can calculate how much space 68 // we allocated in it. 69 size_t _used_bytes_before; 70 71 // When true, indicates that allocate calls should do BOT updates. 72 const bool _bot_updates; 73 74 // Useful for debugging and tracing. 75 const char* _name; 76 77 // A dummy region (i.e., it's been allocated specially for this 78 // purpose and it is not part of the heap) that is full (i.e., top() 79 // == end()). When we don't have a valid active region we make 80 // _alloc_region point to this. This allows us to skip checking 81 // whether the _alloc_region is NULL or not. 82 static HeapRegion* _dummy_region; 83 84 // After a region is allocated by alloc_new_region, this 85 // method is used to set it as the active alloc_region 86 void update_alloc_region(HeapRegion* alloc_region); 87 88 // Allocate a new active region and use it to perform a word_size 89 // allocation. The force parameter will be passed on to 90 // G1CollectedHeap::allocate_new_alloc_region() and tells it to try 91 // to allocate a new region even if the max has been reached. 92 HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force); 93 94 protected: 95 // The memory node index this allocation region belongs to. 96 uint _node_index; 97 98 // Reset the alloc region to point a the dummy region. 99 void reset_alloc_region(); 100 101 // Perform a non-MT-safe allocation out of the given region. 102 inline HeapWord* allocate(HeapRegion* alloc_region, 103 size_t word_size); 104 105 // Perform a MT-safe allocation out of the given region. 106 inline HeapWord* par_allocate(HeapRegion* alloc_region, 107 size_t word_size); 108 // Perform a MT-safe allocation out of the given region, with the given 109 // minimum and desired size. Returns the actual size allocated (between 110 // minimum and desired size) in actual_word_size if the allocation has been 111 // successful. 112 inline HeapWord* par_allocate(HeapRegion* alloc_region, 113 size_t min_word_size, 114 size_t desired_word_size, 115 size_t* actual_word_size); 116 117 // Ensure that the region passed as a parameter has been filled up 118 // so that noone else can allocate out of it any more. 119 // Returns the number of bytes that have been wasted by filled up 120 // the space. 121 size_t fill_up_remaining_space(HeapRegion* alloc_region); 122 123 // Retire the active allocating region. If fill_up is true then make 124 // sure that the region is full before we retire it so that no one 125 // else can allocate out of it. 126 // Returns the number of bytes that have been filled up during retire. 127 virtual size_t retire(bool fill_up); 128 129 size_t retire_internal(HeapRegion* alloc_region, bool fill_up); 130 131 // For convenience as subclasses use it. 132 static G1CollectedHeap* _g1h; 133 134 virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0; 135 virtual void retire_region(HeapRegion* alloc_region, 136 size_t allocated_bytes) = 0; 137 138 G1AllocRegion(const char* name, bool bot_updates, uint node_index); 139 140 public: 141 static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region); 142 get() const143 HeapRegion* get() const { 144 HeapRegion * hr = _alloc_region; 145 // Make sure that the dummy region does not escape this class. 146 return (hr == _dummy_region) ? NULL : hr; 147 } 148 count()149 uint count() { return _count; } 150 151 // The following two are the building blocks for the allocation method. 152 153 // First-level allocation: Should be called without holding a 154 // lock. It will try to allocate lock-free out of the active region, 155 // or return NULL if it was unable to. 156 inline HeapWord* attempt_allocation(size_t word_size); 157 // Perform an allocation out of the current allocation region, with the given 158 // minimum and desired size. Returns the actual size allocated (between 159 // minimum and desired size) in actual_word_size if the allocation has been 160 // successful. 161 // Should be called without holding a lock. It will try to allocate lock-free 162 // out of the active region, or return NULL if it was unable to. 163 inline HeapWord* attempt_allocation(size_t min_word_size, 164 size_t desired_word_size, 165 size_t* actual_word_size); 166 167 // Second-level allocation: Should be called while holding a 168 // lock. It will try to first allocate lock-free out of the active 169 // region or, if it's unable to, it will try to replace the active 170 // alloc region with a new one. We require that the caller takes the 171 // appropriate lock before calling this so that it is easier to make 172 // it conform to its locking protocol. 173 inline HeapWord* attempt_allocation_locked(size_t word_size); 174 // Same as attempt_allocation_locked(size_t, bool), but allowing specification 175 // of minimum word size of the block in min_word_size, and the maximum word 176 // size of the allocation in desired_word_size. The actual size of the block is 177 // returned in actual_word_size. 178 inline HeapWord* attempt_allocation_locked(size_t min_word_size, 179 size_t desired_word_size, 180 size_t* actual_word_size); 181 182 // Should be called to allocate a new region even if the max of this 183 // type of regions has been reached. Should only be called if other 184 // allocation attempts have failed and we are not holding a valid 185 // active region. 186 inline HeapWord* attempt_allocation_force(size_t word_size); 187 188 // Should be called before we start using this object. 189 virtual void init(); 190 191 // This can be used to set the active region to a specific 192 // region. (Use Example: we try to retain the last old GC alloc 193 // region that we've used during a GC and we can use set() to 194 // re-instate it at the beginning of the next GC.) 195 void set(HeapRegion* alloc_region); 196 197 // Should be called when we want to release the active region which 198 // is returned after it's been retired. 199 virtual HeapRegion* release(); 200 201 void trace(const char* str, 202 size_t min_word_size = 0, 203 size_t desired_word_size = 0, 204 size_t actual_word_size = 0, 205 HeapWord* result = NULL) PRODUCT_RETURN; 206 }; 207 208 class MutatorAllocRegion : public G1AllocRegion { 209 private: 210 // Keeps track of the total waste generated during the current 211 // mutator phase. 212 size_t _wasted_bytes; 213 214 // Retained allocation region. Used to lower the waste generated 215 // during mutation by having two active regions if the free space 216 // in a region about to be retired still could fit a TLAB. 217 HeapRegion* volatile _retained_alloc_region; 218 219 // Decide if the region should be retained, based on the free size 220 // in it and the free size in the currently retained region, if any. 221 bool should_retain(HeapRegion* region); 222 protected: 223 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 224 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 225 virtual size_t retire(bool fill_up); 226 public: MutatorAllocRegion(uint node_index)227 MutatorAllocRegion(uint node_index) 228 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */, node_index), 229 _wasted_bytes(0), 230 _retained_alloc_region(NULL) { } 231 232 // Returns the combined used memory in the current alloc region and 233 // the retained alloc region. 234 size_t used_in_alloc_regions(); 235 236 // Perform an allocation out of the retained allocation region, with the given 237 // minimum and desired size. Returns the actual size allocated (between 238 // minimum and desired size) in actual_word_size if the allocation has been 239 // successful. 240 // Should be called without holding a lock. It will try to allocate lock-free 241 // out of the retained region, or return NULL if it was unable to. 242 inline HeapWord* attempt_retained_allocation(size_t min_word_size, 243 size_t desired_word_size, 244 size_t* actual_word_size); 245 246 // This specialization of release() makes sure that the retained alloc 247 // region is retired and set to NULL. 248 virtual HeapRegion* release(); 249 250 virtual void init(); 251 }; 252 253 // Common base class for allocation regions used during GC. 254 class G1GCAllocRegion : public G1AllocRegion { 255 protected: 256 G1EvacStats* _stats; 257 G1HeapRegionAttr::region_type_t _purpose; 258 259 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 260 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 261 262 virtual size_t retire(bool fill_up); 263 G1GCAllocRegion(const char * name,bool bot_updates,G1EvacStats * stats,G1HeapRegionAttr::region_type_t purpose,uint node_index=G1NUMA::AnyNodeIndex)264 G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, 265 G1HeapRegionAttr::region_type_t purpose, uint node_index = G1NUMA::AnyNodeIndex) 266 : G1AllocRegion(name, bot_updates, node_index), _stats(stats), _purpose(purpose) { 267 assert(stats != NULL, "Must pass non-NULL PLAB statistics"); 268 } 269 }; 270 271 class SurvivorGCAllocRegion : public G1GCAllocRegion { 272 public: SurvivorGCAllocRegion(G1EvacStats * stats,uint node_index)273 SurvivorGCAllocRegion(G1EvacStats* stats, uint node_index) 274 : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, G1HeapRegionAttr::Young, node_index) { } 275 }; 276 277 class OldGCAllocRegion : public G1GCAllocRegion { 278 public: OldGCAllocRegion(G1EvacStats * stats)279 OldGCAllocRegion(G1EvacStats* stats) 280 : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, G1HeapRegionAttr::Old) { } 281 282 // This specialization of release() makes sure that the last card that has 283 // been allocated into has been completely filled by a dummy object. This 284 // avoids races when remembered set scanning wants to update the BOT of the 285 // last card in the retained old gc alloc region, and allocation threads 286 // allocating into that card at the same time. 287 virtual HeapRegion* release(); 288 }; 289 290 #endif // SHARE_GC_G1_G1ALLOCREGION_HPP 291