1 /*
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 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
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 24 
 25 #ifndef SHARE_GC_PARALLEL_PSPROMOTIONMANAGER_INLINE_HPP
 26 #define SHARE_GC_PARALLEL_PSPROMOTIONMANAGER_INLINE_HPP
 27 
 28 #include "gc/parallel/psPromotionManager.hpp"
 29 
 30 #include "gc/parallel/parallelScavengeHeap.hpp"
 31 #include "gc/parallel/parMarkBitMap.inline.hpp"
 32 #include "gc/parallel/psOldGen.hpp"
 33 #include "gc/parallel/psPromotionLAB.inline.hpp"
 34 #include "gc/parallel/psScavenge.inline.hpp"
 35 #include "gc/parallel/psStringDedup.hpp"
 36 #include "gc/shared/continuationGCSupport.inline.hpp"
 37 #include "gc/shared/taskqueue.inline.hpp"
 38 #include "gc/shared/tlab_globals.hpp"
 39 #include "logging/log.hpp"
 40 #include "memory/iterator.inline.hpp"
 41 #include "oops/access.inline.hpp"
 42 #include "oops/oop.inline.hpp"
 43 #include "runtime/orderAccess.hpp"
 44 #include "runtime/prefetch.inline.hpp"
 45 #include "utilities/copy.hpp"
 46 
 47 inline PSPromotionManager* PSPromotionManager::manager_array(uint index) {
 48   assert(_manager_array != NULL, "access of NULL manager_array");
 49   assert(index < ParallelGCThreads, "out of range manager_array access");
 50   return &_manager_array[index];
 51 }
 52 
 53 inline void PSPromotionManager::push_depth(ScannerTask task) {
 54   claimed_stack_depth()->push(task);
 55 }
 56 
 57 template <class T>
 58 inline void PSPromotionManager::claim_or_forward_depth(T* p) {
 59   assert(should_scavenge(p, true), "revisiting object?");
 60   assert(ParallelScavengeHeap::heap()->is_in(p), "pointer outside heap");
 61   oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
 62   Prefetch::write(obj->mark_addr(), 0);
 63   push_depth(ScannerTask(p));
 64 }
 65 
 66 inline void PSPromotionManager::promotion_trace_event(oop new_obj, oop old_obj,
 67                                                       size_t obj_size,
 68                                                       uint age, bool tenured,
 69                                                       const PSPromotionLAB* lab) {
 70   // Skip if memory allocation failed
 71   if (new_obj != NULL) {
 72     const ParallelScavengeTracer* gc_tracer = PSScavenge::gc_tracer();
 73 
 74     if (lab != NULL) {
 75       // Promotion of object through newly allocated PLAB
 76       if (gc_tracer->should_report_promotion_in_new_plab_event()) {
 77         size_t obj_bytes = obj_size * HeapWordSize;
 78         size_t lab_size = lab->capacity();
 79         gc_tracer->report_promotion_in_new_plab_event(old_obj->klass(), obj_bytes,
 80                                                       age, tenured, lab_size);
 81       }
 82     } else {
 83       // Promotion of object directly to heap
 84       if (gc_tracer->should_report_promotion_outside_plab_event()) {
 85         size_t obj_bytes = obj_size * HeapWordSize;
 86         gc_tracer->report_promotion_outside_plab_event(old_obj->klass(), obj_bytes,
 87                                                        age, tenured);
 88       }
 89     }
 90   }
 91 }
 92 
 93 class PSPushContentsClosure: public BasicOopIterateClosure {
 94   PSPromotionManager* _pm;
 95  public:
 96   PSPushContentsClosure(PSPromotionManager* pm) : BasicOopIterateClosure(PSScavenge::reference_processor()), _pm(pm) {}
 97 
 98   template <typename T> void do_oop_nv(T* p) {
 99     if (PSScavenge::should_scavenge(p)) {
100       _pm->claim_or_forward_depth(p);
101     }
102   }
103 
104   virtual void do_oop(oop* p)       { do_oop_nv(p); }
105   virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
106 };
107 
108 //
109 // This closure specialization will override the one that is defined in
110 // instanceRefKlass.inline.cpp. It swaps the order of oop_oop_iterate and
111 // oop_oop_iterate_ref_processing. Unfortunately G1 and Parallel behaves
112 // significantly better (especially in the Derby benchmark) using opposite
113 // order of these function calls.
114 //
115 template <>
116 inline void InstanceRefKlass::oop_oop_iterate_reverse<oop, PSPushContentsClosure>(oop obj, PSPushContentsClosure* closure) {
117   oop_oop_iterate_ref_processing<oop>(obj, closure);
118   InstanceKlass::oop_oop_iterate_reverse<oop>(obj, closure);
119 }
120 
121 template <>
122 inline void InstanceRefKlass::oop_oop_iterate_reverse<narrowOop, PSPushContentsClosure>(oop obj, PSPushContentsClosure* closure) {
123   oop_oop_iterate_ref_processing<narrowOop>(obj, closure);
124   InstanceKlass::oop_oop_iterate_reverse<narrowOop>(obj, closure);
125 }
126 
127 inline void PSPromotionManager::push_contents(oop obj) {
128   if (!obj->klass()->is_typeArray_klass()) {
129     PSPushContentsClosure pcc(this);
130     obj->oop_iterate_backwards(&pcc);
131   }
132 }
133 
134 template<bool promote_immediately>
135 inline oop PSPromotionManager::copy_to_survivor_space(oop o) {
136   assert(should_scavenge(&o), "Sanity");
137 
138   // NOTE! We must be very careful with any methods that access the mark
139   // in o. There may be multiple threads racing on it, and it may be forwarded
140   // at any time.
141   markWord m = o->mark();
142   if (!m.is_marked()) {
143     return copy_unmarked_to_survivor_space<promote_immediately>(o, m);
144   } else {
145     // Ensure any loads from the forwardee follow all changes that precede
146     // the release-cmpxchg that performed the forwarding, possibly in some
147     // other thread.
148     OrderAccess::acquire();
149     // Return the already installed forwardee.
150     return cast_to_oop(m.decode_pointer());
151   }
152 }
153 
154 //
155 // This method is pretty bulky. It would be nice to split it up
156 // into smaller submethods, but we need to be careful not to hurt
157 // performance.
158 //
159 template<bool promote_immediately>
160 inline oop PSPromotionManager::copy_unmarked_to_survivor_space(oop o,
161                                                                markWord test_mark) {
162   assert(should_scavenge(&o), "Sanity");
163 
164   oop new_obj = NULL;
165   bool new_obj_is_tenured = false;
166   size_t new_obj_size = o->size();
167 
168   // Find the objects age, MT safe.
169   uint age = (test_mark.has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
170       test_mark.displaced_mark_helper().age() : test_mark.age();
171 
172   if (!promote_immediately) {
173     // Try allocating obj in to-space (unless too old)
174     if (age < PSScavenge::tenuring_threshold()) {
175       new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
176       if (new_obj == NULL && !_young_gen_is_full) {
177         // Do we allocate directly, or flush and refill?
178         if (new_obj_size > (YoungPLABSize / 2)) {
179           // Allocate this object directly
180           new_obj = cast_to_oop(young_space()->cas_allocate(new_obj_size));
181           promotion_trace_event(new_obj, o, new_obj_size, age, false, NULL);
182         } else {
183           // Flush and fill
184           _young_lab.flush();
185 
186           HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
187           if (lab_base != NULL) {
188             _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
189             // Try the young lab allocation again.
190             new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
191             promotion_trace_event(new_obj, o, new_obj_size, age, false, &_young_lab);
192           } else {
193             _young_gen_is_full = true;
194           }
195         }
196       }
197     }
198   }
199 
200   // Otherwise try allocating obj tenured
201   if (new_obj == NULL) {
202 #ifndef PRODUCT
203     if (ParallelScavengeHeap::heap()->promotion_should_fail()) {
204       return oop_promotion_failed(o, test_mark);
205     }
206 #endif  // #ifndef PRODUCT
207 
208     new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
209     new_obj_is_tenured = true;
210 
211     if (new_obj == NULL) {
212       if (!_old_gen_is_full) {
213         // Do we allocate directly, or flush and refill?
214         if (new_obj_size > (OldPLABSize / 2)) {
215           // Allocate this object directly
216           new_obj = cast_to_oop(old_gen()->allocate(new_obj_size));
217           promotion_trace_event(new_obj, o, new_obj_size, age, true, NULL);
218         } else {
219           // Flush and fill
220           _old_lab.flush();
221 
222           HeapWord* lab_base = old_gen()->allocate(OldPLABSize);
223           if(lab_base != NULL) {
224             _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
225             // Try the old lab allocation again.
226             new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
227             promotion_trace_event(new_obj, o, new_obj_size, age, true, &_old_lab);
228           }
229         }
230       }
231 
232       // This is the promotion failed test, and code handling.
233       // The code belongs here for two reasons. It is slightly
234       // different than the code below, and cannot share the
235       // CAS testing code. Keeping the code here also minimizes
236       // the impact on the common case fast path code.
237 
238       if (new_obj == NULL) {
239         _old_gen_is_full = true;
240         return oop_promotion_failed(o, test_mark);
241       }
242     }
243   }
244 
245   assert(new_obj != NULL, "allocation should have succeeded");
246 
247   // Copy obj
248   Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(o), cast_from_oop<HeapWord*>(new_obj), new_obj_size);
249 
250   // Parallel GC claims with a release - so other threads might access this object
251   // after claiming and they should see the "completed" object.
252   ContinuationGCSupport::transform_stack_chunk(new_obj);
253 
254   // Now we have to CAS in the header.
255   // Make copy visible to threads reading the forwardee.
256   oop forwardee = o->forward_to_atomic(new_obj, test_mark, memory_order_release);
257   if (forwardee == NULL) {  // forwardee is NULL when forwarding is successful
258     // We won any races, we "own" this object.
259     assert(new_obj == o->forwardee(), "Sanity");
260 
261     // Increment age if obj still in new generation. Now that
262     // we're dealing with a markWord that cannot change, it is
263     // okay to use the non mt safe oop methods.
264     if (!new_obj_is_tenured) {
265       new_obj->incr_age();
266       assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
267     }
268 
269     // Do the size comparison first with new_obj_size, which we
270     // already have. Hopefully, only a few objects are larger than
271     // _min_array_size_for_chunking, and most of them will be arrays.
272     // So, the is->objArray() test would be very infrequent.
273     if (new_obj_size > _min_array_size_for_chunking &&
274         new_obj->is_objArray() &&
275         PSChunkLargeArrays) {
276       // we'll chunk it
277       push_depth(ScannerTask(PartialArrayScanTask(o)));
278       TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_array_chunk_pushes);
279     } else {
280       // we'll just push its contents
281       push_contents(new_obj);
282 
283       if (StringDedup::is_enabled() &&
284           java_lang_String::is_instance(new_obj) &&
285           psStringDedup::is_candidate_from_evacuation(new_obj, new_obj_is_tenured)) {
286         _string_dedup_requests.add(o);
287       }
288     }
289     return new_obj;
290   } else {
291     // We lost, someone else "owns" this object.
292     // Ensure loads from the forwardee follow all changes that preceded the
293     // release-cmpxchg that performed the forwarding in another thread.
294     OrderAccess::acquire();
295 
296     assert(o->is_forwarded(), "Object must be forwarded if the cas failed.");
297     assert(o->forwardee() == forwardee, "invariant");
298 
299     if (new_obj_is_tenured) {
300       _old_lab.unallocate_object(cast_from_oop<HeapWord*>(new_obj), new_obj_size);
301     } else {
302       _young_lab.unallocate_object(cast_from_oop<HeapWord*>(new_obj), new_obj_size);
303     }
304     return forwardee;
305   }
306 }
307 
308 // Attempt to "claim" oop at p via CAS, push the new obj if successful
309 template <bool promote_immediately, class T>
310 inline void PSPromotionManager::copy_and_push_safe_barrier(T* p) {
311   assert(ParallelScavengeHeap::heap()->is_in_reserved(p), "precondition");
312   assert(should_scavenge(p, true), "revisiting object?");
313 
314   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
315   oop new_obj = copy_to_survivor_space<promote_immediately>(o);
316   RawAccess<IS_NOT_NULL>::oop_store(p, new_obj);
317 
318   if (!PSScavenge::is_obj_in_young((HeapWord*)p) &&
319        PSScavenge::is_obj_in_young(new_obj)) {
320     PSScavenge::card_table()->inline_write_ref_field_gc(p, new_obj);
321   }
322 }
323 
324 inline void PSPromotionManager::process_popped_location_depth(ScannerTask task) {
325   if (task.is_partial_array_task()) {
326     assert(PSChunkLargeArrays, "invariant");
327     process_array_chunk(task.to_partial_array_task());
328   } else {
329     if (task.is_narrow_oop_ptr()) {
330       assert(UseCompressedOops, "Error");
331       copy_and_push_safe_barrier</*promote_immediately=*/false>(task.to_narrow_oop_ptr());
332     } else {
333       copy_and_push_safe_barrier</*promote_immediately=*/false>(task.to_oop_ptr());
334     }
335   }
336 }
337 
338 inline bool PSPromotionManager::steal_depth(int queue_num, ScannerTask& t) {
339   return stack_array_depth()->steal(queue_num, t);
340 }
341 
342 #if TASKQUEUE_STATS
343 void PSPromotionManager::record_steal(ScannerTask task) {
344   if (task.is_partial_array_task()) {
345     ++_array_chunk_steals;
346   }
347 }
348 #endif // TASKQUEUE_STATS
349 
350 #endif // SHARE_GC_PARALLEL_PSPROMOTIONMANAGER_INLINE_HPP