1 /*
   2  * Copyright (c) 2002, 2014, 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 "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
  27 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
  28 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
  29 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
  30 #include "gc_implementation/shared/gcTrace.hpp"
  31 #include "gc_implementation/shared/mutableSpace.hpp"
  32 #include "memory/allocation.inline.hpp"
  33 #include "memory/memRegion.hpp"
  34 #include "memory/padded.inline.hpp"
  35 #include "oops/oop.inline.hpp"
  36 #include "oops/oop.psgc.inline.hpp"
  37 
  38 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  39 
  40 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
  41 OopStarTaskQueueSet*           PSPromotionManager::_stack_array_depth = NULL;
  42 PSOldGen*                      PSPromotionManager::_old_gen = NULL;
  43 MutableSpace*                  PSPromotionManager::_young_space = NULL;
  44 
  45 void PSPromotionManager::initialize() {
  46   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  47   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  48 
  49   _old_gen = heap->old_gen();
  50   _young_space = heap->young_gen()->to_space();
  51 
  52   // To prevent false sharing, we pad the PSPromotionManagers
  53   // and make sure that the first instance starts at a cache line.
  54   assert(_manager_array == NULL, "Attempt to initialize twice");
  55   _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(ParallelGCThreads + 1);
  56   guarantee(_manager_array != NULL, "Could not initialize promotion manager");
  57 
  58   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
  59   guarantee(_stack_array_depth != NULL, "Could not initialize promotion manager");
  60 
  61   // Create and register the PSPromotionManager(s) for the worker threads.
  62   for(uint i=0; i<ParallelGCThreads; i++) {
  63     stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
  64   }
  65   // The VMThread gets its own PSPromotionManager, which is not available
  66   // for work stealing.
  67 }
  68 
  69 // Helper functions to get around the circular dependency between
  70 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
  71 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
  72   return PSScavenge::should_scavenge(p, check_to_space);
  73 }
  74 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
  75   return PSScavenge::should_scavenge(p, check_to_space);
  76 }
  77 
  78 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) {
  79   assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");
  80   assert(_manager_array != NULL, "Sanity");
  81   return &_manager_array[index];
  82 }
  83 
  84 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
  85   assert(_manager_array != NULL, "Sanity");
  86   return &_manager_array[ParallelGCThreads];
  87 }
  88 
  89 void PSPromotionManager::pre_scavenge() {
  90   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  91   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  92 
  93   _young_space = heap->young_gen()->to_space();
  94 
  95   for(uint i=0; i<ParallelGCThreads+1; i++) {
  96     manager_array(i)->reset();
  97   }
  98 }
  99 
 100 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
 101   bool promotion_failure_occurred = false;
 102 
 103   TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
 104   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
 105     PSPromotionManager* manager = manager_array(i);
 106     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
 107     if (manager->_promotion_failed_info.has_failed()) {
 108       gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
 109       promotion_failure_occurred = true;
 110     }
 111     manager->flush_labs();
 112   }
 113   return promotion_failure_occurred;
 114 }
 115 
 116 #if TASKQUEUE_STATS
 117 void
 118 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
 119   #define FMT " " SIZE_FORMAT_W(10)
 120   out->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
 121                 _arrays_chunked, _array_chunks_processed);
 122   #undef FMT
 123 }
 124 
 125 static const char* const pm_stats_hdr[] = {
 126   "    --------masked-------     arrays      array",
 127   "thr       push      steal    chunked     chunks",
 128   "--- ---------- ---------- ---------- ----------"
 129 };
 130 
 131 void
 132 PSPromotionManager::print_taskqueue_stats(outputStream* const out) {
 133   out->print_cr("== GC Tasks Stats, GC %3d",
 134                 Universe::heap()->total_collections());
 135 
 136   TaskQueueStats totals;
 137   out->print("thr "); TaskQueueStats::print_header(1, out); out->cr();
 138   out->print("--- "); TaskQueueStats::print_header(2, out); out->cr();
 139   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 140     TaskQueueStats& next = manager_array(i)->_claimed_stack_depth.stats;
 141     out->print("%3d ", i); next.print(out); out->cr();
 142     totals += next;
 143   }
 144   out->print("tot "); totals.print(out); out->cr();
 145 
 146   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
 147   for (uint i = 0; i < hlines; ++i) out->print_cr("%s", pm_stats_hdr[i]);
 148   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 149     manager_array(i)->print_local_stats(out, i);
 150   }
 151 }
 152 
 153 void
 154 PSPromotionManager::reset_stats() {
 155   claimed_stack_depth()->stats.reset();
 156   _masked_pushes = _masked_steals = 0;
 157   _arrays_chunked = _array_chunks_processed = 0;
 158 }
 159 #endif // TASKQUEUE_STATS
 160 
 161 PSPromotionManager::PSPromotionManager() {
 162   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 163   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 164 
 165   // We set the old lab's start array.
 166   _old_lab.set_start_array(old_gen()->start_array());
 167 
 168   uint queue_size;
 169   claimed_stack_depth()->initialize();
 170   queue_size = claimed_stack_depth()->max_elems();
 171 
 172   _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
 173   if (_totally_drain) {
 174     _target_stack_size = 0;
 175   } else {
 176     // don't let the target stack size to be more than 1/4 of the entries
 177     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
 178                                      (uint) (queue_size / 4));
 179   }
 180 
 181   _array_chunk_size = ParGCArrayScanChunk;
 182   // let's choose 1.5x the chunk size
 183   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
 184 
 185   reset();
 186 }
 187 
 188 void PSPromotionManager::reset() {
 189   assert(stacks_empty(), "reset of non-empty stack");
 190 
 191   // We need to get an assert in here to make sure the labs are always flushed.
 192 
 193   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 194   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 195 
 196   // Do not prefill the LAB's, save heap wastage!
 197   HeapWord* lab_base = young_space()->top();
 198   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
 199   _young_gen_is_full = false;
 200 
 201   lab_base = old_gen()->object_space()->top();
 202   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
 203   _old_gen_is_full = false;
 204 
 205   _promotion_failed_info.reset();
 206 
 207   TASKQUEUE_STATS_ONLY(reset_stats());
 208 }
 209 
 210 
 211 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
 212   totally_drain = totally_drain || _totally_drain;
 213 
 214 #ifdef ASSERT
 215   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 216   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 217   MutableSpace* to_space = heap->young_gen()->to_space();
 218   MutableSpace* old_space = heap->old_gen()->object_space();
 219 #endif /* ASSERT */
 220 
 221   OopStarTaskQueue* const tq = claimed_stack_depth();
 222   do {
 223     StarTask p;
 224 
 225     // Drain overflow stack first, so other threads can steal from
 226     // claimed stack while we work.
 227     while (tq->pop_overflow(p)) {
 228       process_popped_location_depth(p);
 229     }
 230 
 231     if (totally_drain) {
 232       while (tq->pop_local(p)) {
 233         process_popped_location_depth(p);
 234       }
 235     } else {
 236       while (tq->size() > _target_stack_size && tq->pop_local(p)) {
 237         process_popped_location_depth(p);
 238       }
 239     }
 240   } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());
 241 
 242   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
 243   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
 244   assert(tq->overflow_empty(), "Sanity");
 245 }
 246 
 247 void PSPromotionManager::flush_labs() {
 248   assert(stacks_empty(), "Attempt to flush lab with live stack");
 249 
 250   // If either promotion lab fills up, we can flush the
 251   // lab but not refill it, so check first.
 252   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
 253   if (!_young_lab.is_flushed())
 254     _young_lab.flush();
 255 
 256   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
 257   if (!_old_lab.is_flushed())
 258     _old_lab.flush();
 259 
 260   // Let PSScavenge know if we overflowed
 261   if (_young_gen_is_full) {
 262     PSScavenge::set_survivor_overflow(true);
 263   }
 264 }
 265 
 266 template <class T> void PSPromotionManager::process_array_chunk_work(
 267                                                  oop obj,
 268                                                  int start, int end) {
 269   assert(start <= end, "invariant");
 270   T* const base      = (T*)objArrayOop(obj)->base();
 271   T* p               = base + start;
 272   T* const chunk_end = base + end;
 273   while (p < chunk_end) {
 274     if (PSScavenge::should_scavenge(p)) {
 275       claim_or_forward_depth(p);
 276     }
 277     ++p;
 278   }
 279 }
 280 
 281 void PSPromotionManager::process_array_chunk(oop old) {
 282   assert(PSChunkLargeArrays, "invariant");
 283   assert(old->is_objArray(), "invariant");
 284   assert(old->is_forwarded(), "invariant");
 285 
 286   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
 287 
 288   oop const obj = old->forwardee();
 289 
 290   int start;
 291   int const end = arrayOop(old)->length();
 292   if (end > (int) _min_array_size_for_chunking) {
 293     // we'll chunk more
 294     start = end - _array_chunk_size;
 295     assert(start > 0, "invariant");
 296     arrayOop(old)->set_length(start);
 297     push_depth(mask_chunked_array_oop(old));
 298     TASKQUEUE_STATS_ONLY(++_masked_pushes);
 299   } else {
 300     // this is the final chunk for this array
 301     start = 0;
 302     int const actual_length = arrayOop(obj)->length();
 303     arrayOop(old)->set_length(actual_length);
 304   }
 305 
 306   if (UseCompressedOops) {
 307     process_array_chunk_work<narrowOop>(obj, start, end);
 308   } else {
 309     process_array_chunk_work<oop>(obj, start, end);
 310   }
 311 }
 312 
 313 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
 314   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
 315 
 316   // Attempt to CAS in the header.
 317   // This tests if the header is still the same as when
 318   // this started.  If it is the same (i.e., no forwarding
 319   // pointer has been installed), then this thread owns
 320   // it.
 321   if (obj->cas_forward_to(obj, obj_mark)) {
 322     // We won any races, we "own" this object.
 323     assert(obj == obj->forwardee(), "Sanity");
 324 
 325     _promotion_failed_info.register_copy_failure(obj->size());
 326 
 327     obj->push_contents(this);
 328 
 329     // Save the mark if needed
 330     PSScavenge::oop_promotion_failed(obj, obj_mark);
 331   }  else {
 332     // We lost, someone else "owns" this object
 333     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
 334 
 335     // No unallocation to worry about.
 336     obj = obj->forwardee();
 337   }
 338 
 339 #ifndef PRODUCT
 340   if (TraceScavenge) {
 341     gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " (%d)}",
 342                            "promotion-failure",
 343                            obj->klass()->internal_name(),
 344                            (void *)obj, obj->size());
 345 
 346   }
 347 #endif
 348 
 349   return obj;
 350 }