1 /*
   2  * Copyright (c) 2001, 2013, 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/shared/collectorCounters.hpp"
  27 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/blockOffsetTable.inline.hpp"
  30 #include "memory/generation.inline.hpp"
  31 #include "memory/generationSpec.hpp"
  32 #include "memory/space.hpp"
  33 #include "memory/tenuredGeneration.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "runtime/java.hpp"
  36 #include "utilities/macros.hpp"
  37 
  38 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
  39                                      size_t initial_byte_size, int level,
  40                                      GenRemSet* remset) :
  41   OneContigSpaceCardGeneration(rs, initial_byte_size,
  42                                level, remset, NULL)
  43 {
  44   HeapWord* bottom = (HeapWord*) _virtual_space.low();
  45   HeapWord* end    = (HeapWord*) _virtual_space.high();
  46   _the_space  = new TenuredSpace(_bts, MemRegion(bottom, end));
  47   _the_space->reset_saved_mark();
  48   _shrink_factor = 0;
  49   _capacity_at_prologue = 0;
  50 
  51   _gc_stats = new GCStats();
  52 
  53   // initialize performance counters
  54 
  55   const char* gen_name = "old";
  56   GenCollectorPolicy* gcp = (GenCollectorPolicy*) GenCollectedHeap::heap()->collector_policy();
  57 
  58   // Generation Counters -- generation 1, 1 subspace
  59   _gen_counters = new GenerationCounters(gen_name, 1, 1,
  60       gcp->min_old_size(), gcp->max_old_size(), &_virtual_space);
  61 
  62   _gc_counters = new CollectorCounters("MSC", 1);
  63 
  64   _space_counters = new CSpaceCounters(gen_name, 0,
  65                                        _virtual_space.reserved_size(),
  66                                        _the_space, _gen_counters);
  67 #if INCLUDE_ALL_GCS
  68   if (UseParNewGC) {
  69     typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;
  70     _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,
  71                                       ParallelGCThreads, mtGC);
  72     if (_alloc_buffers == NULL)
  73       vm_exit_during_initialization("Could not allocate alloc_buffers");
  74     for (uint i = 0; i < ParallelGCThreads; i++) {
  75       _alloc_buffers[i] =
  76         new ParGCAllocBufferWithBOT(OldPLABSize, _bts);
  77       if (_alloc_buffers[i] == NULL)
  78         vm_exit_during_initialization("Could not allocate alloc_buffers");
  79     }
  80   } else {
  81     _alloc_buffers = NULL;
  82   }
  83 #endif // INCLUDE_ALL_GCS
  84 }
  85 
  86 
  87 const char* TenuredGeneration::name() const {
  88   return "tenured generation";
  89 }
  90 
  91 void TenuredGeneration::gc_prologue(bool full) {
  92   _capacity_at_prologue = capacity();
  93   _used_at_prologue = used();
  94   if (VerifyBeforeGC) {
  95     verify_alloc_buffers_clean();
  96   }
  97 }
  98 
  99 void TenuredGeneration::gc_epilogue(bool full) {
 100   if (VerifyAfterGC) {
 101     verify_alloc_buffers_clean();
 102   }
 103   OneContigSpaceCardGeneration::gc_epilogue(full);
 104 }
 105 
 106 
 107 bool TenuredGeneration::should_collect(bool  full,
 108                                        size_t size,
 109                                        bool   is_tlab) {
 110   // This should be one big conditional or (||), but I want to be able to tell
 111   // why it returns what it returns (without re-evaluating the conditionals
 112   // in case they aren't idempotent), so I'm doing it this way.
 113   // DeMorgan says it's okay.
 114   bool result = false;
 115   if (!result && full) {
 116     result = true;
 117     if (PrintGC && Verbose) {
 118       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 119                     " full");
 120     }
 121   }
 122   if (!result && should_allocate(size, is_tlab)) {
 123     result = true;
 124     if (PrintGC && Verbose) {
 125       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 126                     " should_allocate(" SIZE_FORMAT ")",
 127                     size);
 128     }
 129   }
 130   // If we don't have very much free space.
 131   // XXX: 10000 should be a percentage of the capacity!!!
 132   if (!result && free() < 10000) {
 133     result = true;
 134     if (PrintGC && Verbose) {
 135       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 136                     " free(): " SIZE_FORMAT,
 137                     free());
 138     }
 139   }
 140   // If we had to expand to accommodate promotions from younger generations
 141   if (!result && _capacity_at_prologue < capacity()) {
 142     result = true;
 143     if (PrintGC && Verbose) {
 144       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 145                     "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
 146                     _capacity_at_prologue, capacity());
 147     }
 148   }
 149   return result;
 150 }
 151 
 152 void TenuredGeneration::collect(bool   full,
 153                                 bool   clear_all_soft_refs,
 154                                 size_t size,
 155                                 bool   is_tlab) {
 156   retire_alloc_buffers_before_full_gc();
 157   OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
 158                                         size, is_tlab);
 159 }
 160 
 161 void TenuredGeneration::compute_new_size() {
 162   assert_locked_or_safepoint(Heap_lock);
 163 
 164   // Compute some numbers about the state of the heap.
 165   const size_t used_after_gc = used();
 166   const size_t capacity_after_gc = capacity();
 167 
 168   CardGeneration::compute_new_size();
 169 
 170   assert(used() == used_after_gc && used_after_gc <= capacity(),
 171          err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
 172          " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
 173 }
 174 void TenuredGeneration::update_gc_stats(int current_level,
 175                                         bool full) {
 176   // If the next lower level(s) has been collected, gather any statistics
 177   // that are of interest at this point.
 178   if (!full && (current_level + 1) == level()) {
 179     // Calculate size of data promoted from the younger generations
 180     // before doing the collection.
 181     size_t used_before_gc = used();
 182 
 183     // If the younger gen collections were skipped, then the
 184     // number of promoted bytes will be 0 and adding it to the
 185     // average will incorrectly lessen the average.  It is, however,
 186     // also possible that no promotion was needed.
 187     if (used_before_gc >= _used_at_prologue) {
 188       size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
 189       gc_stats()->avg_promoted()->sample(promoted_in_bytes);
 190     }
 191   }
 192 }
 193 
 194 void TenuredGeneration::update_counters() {
 195   if (UsePerfData) {
 196     _space_counters->update_all();
 197     _gen_counters->update_all();
 198   }
 199 }
 200 
 201 
 202 #if INCLUDE_ALL_GCS
 203 oop TenuredGeneration::par_promote(int thread_num,
 204                                    oop old, markOop m, size_t word_sz) {
 205 
 206   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 207   HeapWord* obj_ptr = buf->allocate(word_sz);
 208   bool is_lab = true;
 209   if (obj_ptr == NULL) {
 210 #ifndef PRODUCT
 211     if (Universe::heap()->promotion_should_fail()) {
 212       return NULL;
 213     }
 214 #endif  // #ifndef PRODUCT
 215 
 216     // Slow path:
 217     if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {
 218       // Is small enough; abandon this buffer and start a new one.
 219       size_t buf_size = buf->word_sz();
 220       HeapWord* buf_space =
 221         TenuredGeneration::par_allocate(buf_size, false);
 222       if (buf_space == NULL) {
 223         buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);
 224       }
 225       if (buf_space != NULL) {
 226         buf->retire(false, false);
 227         buf->set_buf(buf_space);
 228         obj_ptr = buf->allocate(word_sz);
 229         assert(obj_ptr != NULL, "Buffer was definitely big enough...");
 230       }
 231     };
 232     // Otherwise, buffer allocation failed; try allocating object
 233     // individually.
 234     if (obj_ptr == NULL) {
 235       obj_ptr = TenuredGeneration::par_allocate(word_sz, false);
 236       if (obj_ptr == NULL) {
 237         obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);
 238       }
 239     }
 240     if (obj_ptr == NULL) return NULL;
 241   }
 242   assert(obj_ptr != NULL, "program logic");
 243   Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);
 244   oop obj = oop(obj_ptr);
 245   // Restore the mark word copied above.
 246   obj->set_mark(m);
 247   return obj;
 248 }
 249 
 250 void TenuredGeneration::par_promote_alloc_undo(int thread_num,
 251                                                HeapWord* obj,
 252                                                size_t word_sz) {
 253   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 254   if (buf->contains(obj)) {
 255     guarantee(buf->contains(obj + word_sz - 1),
 256               "should contain whole object");
 257     buf->undo_allocation(obj, word_sz);
 258   } else {
 259     CollectedHeap::fill_with_object(obj, word_sz);
 260   }
 261 }
 262 
 263 void TenuredGeneration::par_promote_alloc_done(int thread_num) {
 264   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 265   buf->retire(true, ParallelGCRetainPLAB);
 266 }
 267 
 268 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {
 269   if (UseParNewGC) {
 270     for (uint i = 0; i < ParallelGCThreads; i++) {
 271       _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);
 272     }
 273   }
 274 }
 275 
 276 // Verify that any retained parallel allocation buffers do not
 277 // intersect with dirty cards.
 278 void TenuredGeneration::verify_alloc_buffers_clean() {
 279   if (UseParNewGC) {
 280     for (uint i = 0; i < ParallelGCThreads; i++) {
 281       _rs->verify_aligned_region_empty(_alloc_buffers[i]->range());
 282     }
 283   }
 284 }
 285 
 286 #else  // INCLUDE_ALL_GCS
 287 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}
 288 void TenuredGeneration::verify_alloc_buffers_clean() {}
 289 #endif // INCLUDE_ALL_GCS
 290 
 291 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
 292   size_t available = max_contiguous_available();
 293   size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();
 294   bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);
 295   if (PrintGC && Verbose) {
 296     gclog_or_tty->print_cr(
 297       "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
 298       "max_promo("SIZE_FORMAT")",
 299       res? "":" not", available, res? ">=":"<",
 300       av_promo, max_promotion_in_bytes);
 301   }
 302   return res;
 303 }