1 /*
   2  * Copyright (c) 2002, 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 #include "precompiled.hpp"
  26 #include "classfile/javaClasses.inline.hpp"
  27 #include "gc/parallel/mutableSpace.hpp"
  28 #include "gc/parallel/parallelScavengeHeap.hpp"
  29 #include "gc/parallel/psOldGen.hpp"
  30 #include "gc/parallel/psPromotionManager.inline.hpp"
  31 #include "gc/parallel/psScavenge.inline.hpp"
  32 #include "gc/shared/gcTrace.hpp"
  33 #include "gc/shared/preservedMarks.inline.hpp"
  34 #include "gc/shared/taskqueue.inline.hpp"
  35 #include "logging/log.hpp"
  36 #include "logging/logStream.hpp"
  37 #include "memory/allocation.inline.hpp"
  38 #include "memory/iterator.inline.hpp"
  39 #include "memory/memRegion.hpp"
  40 #include "memory/padded.inline.hpp"
  41 #include "memory/resourceArea.hpp"
  42 #include "oops/access.inline.hpp"
  43 #include "oops/compressedOops.inline.hpp"
  44 
  45 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
  46 OopStarTaskQueueSet*           PSPromotionManager::_stack_array_depth = NULL;
  47 PreservedMarksSet*             PSPromotionManager::_preserved_marks_set = NULL;
  48 PSOldGen*                      PSPromotionManager::_old_gen = NULL;
  49 MutableSpace*                  PSPromotionManager::_young_space = NULL;
  50 
  51 void PSPromotionManager::initialize() {
  52   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  53 
  54   _old_gen = heap->old_gen();
  55   _young_space = heap->young_gen()->to_space();
  56 
  57   const uint promotion_manager_num = ParallelGCThreads + 1;
  58 
  59   // To prevent false sharing, we pad the PSPromotionManagers
  60   // and make sure that the first instance starts at a cache line.
  61   assert(_manager_array == NULL, "Attempt to initialize twice");
  62   _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
  63   guarantee(_manager_array != NULL, "Could not initialize promotion manager");
  64 
  65   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
  66   guarantee(_stack_array_depth != NULL, "Could not initialize promotion manager");
  67 
  68   // Create and register the PSPromotionManager(s) for the worker threads.
  69   for(uint i=0; i<ParallelGCThreads; i++) {
  70     stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
  71   }
  72   // The VMThread gets its own PSPromotionManager, which is not available
  73   // for work stealing.
  74 
  75   assert(_preserved_marks_set == NULL, "Attempt to initialize twice");
  76   _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
  77   guarantee(_preserved_marks_set != NULL, "Could not initialize preserved marks set");
  78   _preserved_marks_set->init(promotion_manager_num);
  79   for (uint i = 0; i < promotion_manager_num; i += 1) {
  80     _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
  81   }
  82 }
  83 
  84 // Helper functions to get around the circular dependency between
  85 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
  86 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
  87   return PSScavenge::should_scavenge(p, check_to_space);
  88 }
  89 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
  90   return PSScavenge::should_scavenge(p, check_to_space);
  91 }
  92 
  93 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
  94   assert(index < ParallelGCThreads, "index out of range");
  95   assert(_manager_array != NULL, "Sanity");
  96   return &_manager_array[index];
  97 }
  98 
  99 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
 100   assert(_manager_array != NULL, "Sanity");
 101   return &_manager_array[ParallelGCThreads];
 102 }
 103 
 104 void PSPromotionManager::pre_scavenge() {
 105   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 106 
 107   _preserved_marks_set->assert_empty();
 108   _young_space = heap->young_gen()->to_space();
 109 
 110   for(uint i=0; i<ParallelGCThreads+1; i++) {
 111     manager_array(i)->reset();
 112   }
 113 }
 114 
 115 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
 116   bool promotion_failure_occurred = false;
 117 
 118   TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
 119   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
 120     PSPromotionManager* manager = manager_array(i);
 121     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
 122     if (manager->_promotion_failed_info.has_failed()) {
 123       gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
 124       promotion_failure_occurred = true;
 125     }
 126     manager->flush_labs();
 127   }
 128   if (!promotion_failure_occurred) {
 129     // If there was no promotion failure, the preserved mark stacks
 130     // should be empty.
 131     _preserved_marks_set->assert_empty();
 132   }
 133   return promotion_failure_occurred;
 134 }
 135 
 136 #if TASKQUEUE_STATS
 137 void
 138 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
 139   #define FMT " " SIZE_FORMAT_W(10)
 140   out->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
 141                 _arrays_chunked, _array_chunks_processed);
 142   #undef FMT
 143 }
 144 
 145 static const char* const pm_stats_hdr[] = {
 146   "    --------masked-------     arrays      array",
 147   "thr       push      steal    chunked     chunks",
 148   "--- ---------- ---------- ---------- ----------"
 149 };
 150 
 151 void
 152 PSPromotionManager::print_taskqueue_stats() {
 153   if (!log_is_enabled(Trace, gc, task, stats)) {
 154     return;
 155   }
 156   Log(gc, task, stats) log;
 157   ResourceMark rm;
 158   LogStream ls(log.trace());
 159   outputStream* out = &ls;
 160   out->print_cr("== GC Tasks Stats, GC %3d",
 161                 ParallelScavengeHeap::heap()->total_collections());
 162 
 163   TaskQueueStats totals;
 164   out->print("thr "); TaskQueueStats::print_header(1, out); out->cr();
 165   out->print("--- "); TaskQueueStats::print_header(2, out); out->cr();
 166   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 167     TaskQueueStats& next = manager_array(i)->_claimed_stack_depth.stats;
 168     out->print("%3d ", i); next.print(out); out->cr();
 169     totals += next;
 170   }
 171   out->print("tot "); totals.print(out); out->cr();
 172 
 173   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
 174   for (uint i = 0; i < hlines; ++i) out->print_cr("%s", pm_stats_hdr[i]);
 175   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 176     manager_array(i)->print_local_stats(out, i);
 177   }
 178 }
 179 
 180 void
 181 PSPromotionManager::reset_stats() {
 182   claimed_stack_depth()->stats.reset();
 183   _masked_pushes = _masked_steals = 0;
 184   _arrays_chunked = _array_chunks_processed = 0;
 185 }
 186 #endif // TASKQUEUE_STATS
 187 
 188 PSPromotionManager::PSPromotionManager() {
 189   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 190 
 191   // We set the old lab's start array.
 192   _old_lab.set_start_array(old_gen()->start_array());
 193 
 194   uint queue_size;
 195   claimed_stack_depth()->initialize();
 196   queue_size = claimed_stack_depth()->max_elems();
 197 
 198   _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
 199   if (_totally_drain) {
 200     _target_stack_size = 0;
 201   } else {
 202     // don't let the target stack size to be more than 1/4 of the entries
 203     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
 204                                      (uint) (queue_size / 4));
 205   }
 206 
 207   _array_chunk_size = ParGCArrayScanChunk;
 208   // let's choose 1.5x the chunk size
 209   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
 210 
 211   _preserved_marks = NULL;
 212 
 213   reset();
 214 }
 215 
 216 void PSPromotionManager::reset() {
 217   assert(stacks_empty(), "reset of non-empty stack");
 218 
 219   // We need to get an assert in here to make sure the labs are always flushed.
 220 
 221   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 222 
 223   // Do not prefill the LAB's, save heap wastage!
 224   HeapWord* lab_base = young_space()->top();
 225   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
 226   _young_gen_is_full = false;
 227 
 228   lab_base = old_gen()->object_space()->top();
 229   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
 230   _old_gen_is_full = false;
 231 
 232   _promotion_failed_info.reset();
 233 
 234   TASKQUEUE_STATS_ONLY(reset_stats());
 235 }
 236 
 237 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
 238   assert(_preserved_marks == NULL, "do not set it twice");
 239   _preserved_marks = preserved_marks;
 240 }
 241 
 242 void PSPromotionManager::restore_preserved_marks() {
 243   SharedRestorePreservedMarksTaskExecutor task_executor(&ParallelScavengeHeap::heap()->workers());
 244   _preserved_marks_set->restore(&task_executor);
 245 }
 246 
 247 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
 248   totally_drain = totally_drain || _totally_drain;
 249 
 250 #ifdef ASSERT
 251   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 252   MutableSpace* to_space = heap->young_gen()->to_space();
 253   MutableSpace* old_space = heap->old_gen()->object_space();
 254 #endif /* ASSERT */
 255 
 256   OopStarTaskQueue* const tq = claimed_stack_depth();
 257   do {
 258     StarTask p;
 259 
 260     // Drain overflow stack first, so other threads can steal from
 261     // claimed stack while we work.
 262     while (tq->pop_overflow(p)) {
 263       process_popped_location_depth(p);
 264     }
 265 
 266     if (totally_drain) {
 267       while (tq->pop_local(p)) {
 268         process_popped_location_depth(p);
 269       }
 270     } else {
 271       while (tq->size() > _target_stack_size && tq->pop_local(p)) {
 272         process_popped_location_depth(p);
 273       }
 274     }
 275   } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
 276 
 277   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
 278   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
 279   assert(tq->overflow_empty(), "Sanity");
 280 }
 281 
 282 void PSPromotionManager::flush_labs() {
 283   assert(stacks_empty(), "Attempt to flush lab with live stack");
 284 
 285   // If either promotion lab fills up, we can flush the
 286   // lab but not refill it, so check first.
 287   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
 288   if (!_young_lab.is_flushed())
 289     _young_lab.flush();
 290 
 291   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
 292   if (!_old_lab.is_flushed())
 293     _old_lab.flush();
 294 
 295   // Let PSScavenge know if we overflowed
 296   if (_young_gen_is_full) {
 297     PSScavenge::set_survivor_overflow(true);
 298   }
 299 }
 300 
 301 template <class T> void PSPromotionManager::process_array_chunk_work(
 302                                                  oop obj,
 303                                                  int start, int end) {
 304   assert(start <= end, "invariant");
 305   T* const base      = (T*)objArrayOop(obj)->base();
 306   T* p               = base + start;
 307   T* const chunk_end = base + end;
 308   while (p < chunk_end) {
 309     if (PSScavenge::should_scavenge(p)) {
 310       claim_or_forward_depth(p);
 311     }
 312     ++p;
 313   }
 314 }
 315 
 316 void PSPromotionManager::process_array_chunk(oop old) {
 317   assert(PSChunkLargeArrays, "invariant");
 318   assert(old->is_objArray(), "invariant");
 319   assert(old->is_forwarded(), "invariant");
 320 
 321   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
 322 
 323   oop const obj = old->forwardee();
 324 
 325   int start;
 326   int const end = arrayOop(old)->length();
 327   if (end > (int) _min_array_size_for_chunking) {
 328     // we'll chunk more
 329     start = end - _array_chunk_size;
 330     assert(start > 0, "invariant");
 331     arrayOop(old)->set_length(start);
 332     push_depth(mask_chunked_array_oop(old));
 333     TASKQUEUE_STATS_ONLY(++_masked_pushes);
 334   } else {
 335     // this is the final chunk for this array
 336     start = 0;
 337     int const actual_length = arrayOop(obj)->length();
 338     arrayOop(old)->set_length(actual_length);
 339   }
 340 
 341   if (UseCompressedOops) {
 342     process_array_chunk_work<narrowOop>(obj, start, end);
 343   } else {
 344     process_array_chunk_work<oop>(obj, start, end);
 345   }
 346 }
 347 
 348 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
 349   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
 350 
 351   // Attempt to CAS in the header.
 352   // This tests if the header is still the same as when
 353   // this started.  If it is the same (i.e., no forwarding
 354   // pointer has been installed), then this thread owns
 355   // it.
 356   if (obj->cas_forward_to(obj, obj_mark)) {
 357     // We won any races, we "own" this object.
 358     assert(obj == obj->forwardee(), "Sanity");
 359 
 360     _promotion_failed_info.register_copy_failure(obj->size());
 361 
 362     push_contents(obj);
 363 
 364     _preserved_marks->push_if_necessary(obj, obj_mark);
 365   }  else {
 366     // We lost, someone else "owns" this object
 367     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
 368 
 369     // No unallocation to worry about.
 370     obj = obj->forwardee();
 371   }
 372 
 373   log_develop_trace(gc, scavenge)("{promotion-failure %s " PTR_FORMAT " (%d)}", obj->klass()->internal_name(), p2i(obj), obj->size());
 374 
 375   return obj;
 376 }