1 /* 2 * Copyright (c) 2011, 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_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 // 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing 35 #define G1_ALLOC_REGION_TRACING 0 36 37 // A class that holds a region that is active in satisfying allocation 38 // requests, potentially issued in parallel. When the active region is 39 // full it will be retired and replaced with a new one. The 40 // implementation assumes that fast-path allocations will be lock-free 41 // and a lock will need to be taken when the active region needs to be 42 // replaced. 43 44 class G1AllocRegion VALUE_OBJ_CLASS_SPEC { 45 46 private: 47 // The active allocating region we are currently allocating out 48 // of. The invariant is that if this object is initialized (i.e., 49 // init() has been called and release() has not) then _alloc_region 50 // is either an active allocating region or the dummy region (i.e., 51 // it can never be NULL) and this object can be used to satisfy 52 // allocation requests. If this object is not initialized 53 // (i.e. init() has not been called or release() has been called) 54 // then _alloc_region is NULL and this object should not be used to 55 // satisfy allocation requests (it was done this way to force the 56 // correct use of init() and release()). 57 HeapRegion* volatile _alloc_region; 58 59 // Allocation context associated with this alloc region. 60 AllocationContext_t _allocation_context; 61 62 // It keeps track of the distinct number of regions that are used 63 // for allocation in the active interval of this object, i.e., 64 // between a call to init() and a call to release(). The count 65 // mostly includes regions that are freshly allocated, as well as 66 // the region that is re-used using the set() method. This count can 67 // be used in any heuristics that might want to bound how many 68 // distinct regions this object can used during an active interval. 69 uint _count; 70 71 // When we set up a new active region we save its used bytes in this 72 // field so that, when we retire it, we can calculate how much space 73 // we allocated in it. 74 size_t _used_bytes_before; 75 76 // When true, indicates that allocate calls should do BOT updates. 77 const bool _bot_updates; 78 79 // Useful for debugging and tracing. 80 const char* _name; 81 82 // A dummy region (i.e., it's been allocated specially for this 83 // purpose and it is not part of the heap) that is full (i.e., top() 84 // == end()). When we don't have a valid active region we make 85 // _alloc_region point to this. This allows us to skip checking 86 // whether the _alloc_region is NULL or not. 87 static HeapRegion* _dummy_region; 88 89 // Some of the methods below take a bot_updates parameter. Its value 90 // should be the same as the _bot_updates field. The idea is that 91 // the parameter will be a constant for a particular alloc region 92 // and, given that these methods will be hopefully inlined, the 93 // compiler should compile out the test. 94 95 // Perform a non-MT-safe allocation out of the given region. 96 static inline HeapWord* allocate(HeapRegion* alloc_region, 97 size_t word_size, 98 bool bot_updates); 99 100 // Perform a MT-safe allocation out of the given region. 101 static inline HeapWord* par_allocate(HeapRegion* alloc_region, 102 size_t word_size, 103 bool bot_updates); 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 static 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 bool bot_updates); 113 114 // Ensure that the region passed as a parameter has been filled up 115 // so that noone else can allocate out of it any more. 116 // Returns the number of bytes that have been wasted by filled up 117 // the space. 118 static size_t fill_up_remaining_space(HeapRegion* alloc_region, 119 bool bot_updates); 120 121 // After a region is allocated by alloc_new_region, this 122 // method is used to set it as the active alloc_region 123 void update_alloc_region(HeapRegion* alloc_region); 124 125 // Allocate a new active region and use it to perform a word_size 126 // allocation. The force parameter will be passed on to 127 // G1CollectedHeap::allocate_new_alloc_region() and tells it to try 128 // to allocate a new region even if the max has been reached. 129 HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force); 130 131 protected: 132 // Retire the active allocating region. If fill_up is true then make 133 // sure that the region is full before we retire it so that no one 134 // else can allocate out of it. 135 // Returns the number of bytes that have been filled up during retire. 136 virtual size_t retire(bool fill_up); 137 138 // For convenience as subclasses use it. 139 static G1CollectedHeap* _g1h; 140 141 virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0; 142 virtual void retire_region(HeapRegion* alloc_region, 143 size_t allocated_bytes) = 0; 144 145 G1AllocRegion(const char* name, bool bot_updates); 146 147 public: 148 static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region); 149 150 HeapRegion* get() const { 151 HeapRegion * hr = _alloc_region; 152 // Make sure that the dummy region does not escape this class. 153 return (hr == _dummy_region) ? NULL : hr; 154 } 155 156 void set_allocation_context(AllocationContext_t context) { _allocation_context = context; } 157 AllocationContext_t allocation_context() { return _allocation_context; } 158 159 uint count() { return _count; } 160 161 // The following two are the building blocks for the allocation method. 162 163 // First-level allocation: Should be called without holding a 164 // lock. It will try to allocate lock-free out of the active region, 165 // or return NULL if it was unable to. 166 inline HeapWord* attempt_allocation(size_t word_size, 167 bool bot_updates); 168 // Perform an allocation out of the current allocation region, with the given 169 // minimum and desired size. Returns the actual size allocated (between 170 // minimum and desired size) in actual_word_size if the allocation has been 171 // successful. 172 // Should be called without holding a lock. It will try to allocate lock-free 173 // out of the active region, or return NULL if it was unable to. 174 inline HeapWord* attempt_allocation(size_t min_word_size, 175 size_t desired_word_size, 176 size_t* actual_word_size, 177 bool bot_updates); 178 179 // Second-level allocation: Should be called while holding a 180 // lock. It will try to first allocate lock-free out of the active 181 // region or, if it's unable to, it will try to replace the active 182 // alloc region with a new one. We require that the caller takes the 183 // appropriate lock before calling this so that it is easier to make 184 // it conform to its locking protocol. 185 inline HeapWord* attempt_allocation_locked(size_t word_size, 186 bool bot_updates); 187 // Same as attempt_allocation_locked(size_t, bool), but allowing specification 188 // of minimum word size of the block in min_word_size, and the maximum word 189 // size of the allocation in desired_word_size. The actual size of the block is 190 // returned in actual_word_size. 191 inline HeapWord* attempt_allocation_locked(size_t min_word_size, 192 size_t desired_word_size, 193 size_t* actual_word_size, 194 bool bot_updates); 195 196 // Should be called to allocate a new region even if the max of this 197 // type of regions has been reached. Should only be called if other 198 // allocation attempts have failed and we are not holding a valid 199 // active region. 200 inline HeapWord* attempt_allocation_force(size_t word_size, 201 bool bot_updates); 202 203 // Should be called before we start using this object. 204 void init(); 205 206 // This can be used to set the active region to a specific 207 // region. (Use Example: we try to retain the last old GC alloc 208 // region that we've used during a GC and we can use set() to 209 // re-instate it at the beginning of the next GC.) 210 void set(HeapRegion* alloc_region); 211 212 // Should be called when we want to release the active region which 213 // is returned after it's been retired. 214 virtual HeapRegion* release(); 215 216 #if G1_ALLOC_REGION_TRACING 217 void trace(const char* str, 218 size_t min_word_size = 0, 219 size_t desired_word_size = 0, 220 size_t actual_word_size = 0, 221 HeapWord* result = NULL); 222 #else // G1_ALLOC_REGION_TRACING 223 void trace(const char* str, 224 size_t min_word_size = 0, 225 size_t desired_word_size = 0, 226 size_t actual_word_size = 0, 227 HeapWord* result = NULL) { } 228 #endif // G1_ALLOC_REGION_TRACING 229 }; 230 231 class MutatorAllocRegion : public G1AllocRegion { 232 protected: 233 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 234 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 235 public: 236 MutatorAllocRegion() 237 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 238 }; 239 240 // Common base class for allocation regions used during GC. 241 class G1GCAllocRegion : public G1AllocRegion { 242 protected: 243 G1EvacStats* _stats; 244 InCSetState::in_cset_state_t _purpose; 245 246 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 247 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 248 249 virtual size_t retire(bool fill_up); 250 public: 251 G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, InCSetState::in_cset_state_t purpose) 252 : G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) { 253 assert(stats != NULL, "Must pass non-NULL PLAB statistics"); 254 } 255 }; 256 257 class SurvivorGCAllocRegion : public G1GCAllocRegion { 258 public: 259 SurvivorGCAllocRegion(G1EvacStats* stats) 260 : G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, InCSetState::Young) { } 261 }; 262 263 class OldGCAllocRegion : public G1GCAllocRegion { 264 public: 265 OldGCAllocRegion(G1EvacStats* stats) 266 : G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, InCSetState::Old) { } 267 268 // This specialization of release() makes sure that the last card that has 269 // been allocated into has been completely filled by a dummy object. This 270 // avoids races when remembered set scanning wants to update the BOT of the 271 // last card in the retained old gc alloc region, and allocation threads 272 // allocating into that card at the same time. 273 virtual HeapRegion* release(); 274 }; 275 276 #endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP