1 /*
   2  * Copyright (c) 2001, 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 #include "precompiled.hpp"
  26 #include "gc_implementation/shared/collectorCounters.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "memory/blockOffsetTable.inline.hpp"
  29 #include "memory/generation.inline.hpp"
  30 #include "memory/generationSpec.hpp"
  31 #include "memory/space.hpp"
  32 #include "memory/tenuredGeneration.hpp"
  33 #include "oops/oop.inline.hpp"
  34 #include "runtime/java.hpp"
  35 #include "utilities/macros.hpp"
  36 
  37 #if INCLUDE_ALL_GCS
  38 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
  39 #endif
  40 
  41 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
  42                                      size_t initial_byte_size, int level,
  43                                      GenRemSet* remset) :
  44   OneContigSpaceCardGeneration(rs, initial_byte_size,
  45                                level, remset, NULL)
  46 {
  47   HeapWord* bottom = (HeapWord*) _virtual_space.low();
  48   HeapWord* end    = (HeapWord*) _virtual_space.high();
  49   _the_space  = new TenuredSpace(_bts, MemRegion(bottom, end));
  50   _the_space->reset_saved_mark();
  51   _shrink_factor = 0;
  52   _capacity_at_prologue = 0;
  53 
  54   _gc_stats = new GCStats();
  55 
  56   // initialize performance counters
  57 
  58   const char* gen_name = "old";
  59 
  60   // Generation Counters -- generation 1, 1 subspace
  61   _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space);
  62 
  63   _gc_counters = new CollectorCounters("MSC", 1);
  64 
  65   _space_counters = new CSpaceCounters(gen_name, 0,
  66                                        _virtual_space.reserved_size(),
  67                                        _the_space, _gen_counters);
  68 #if INCLUDE_ALL_GCS
  69   if (UseParNewGC) {
  70     typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;
  71     _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,
  72                                       ParallelGCThreads, mtGC);
  73     if (_alloc_buffers == NULL)
  74       vm_exit_during_initialization("Could not allocate alloc_buffers");
  75     for (uint i = 0; i < ParallelGCThreads; i++) {
  76       _alloc_buffers[i] =
  77         new ParGCAllocBufferWithBOT(OldPLABSize, _bts);
  78       if (_alloc_buffers[i] == NULL)
  79         vm_exit_during_initialization("Could not allocate alloc_buffers");
  80     }
  81   } else {
  82     _alloc_buffers = NULL;
  83   }
  84 #endif // INCLUDE_ALL_GCS
  85 }
  86 
  87 
  88 const char* TenuredGeneration::name() const {
  89   return "tenured generation";
  90 }
  91 
  92 void TenuredGeneration::gc_prologue(bool full) {
  93   _capacity_at_prologue = capacity();
  94   _used_at_prologue = used();
  95   if (VerifyBeforeGC) {
  96     verify_alloc_buffers_clean();
  97   }
  98 }
  99 
 100 void TenuredGeneration::gc_epilogue(bool full) {
 101   if (VerifyAfterGC) {
 102     verify_alloc_buffers_clean();
 103   }
 104   OneContigSpaceCardGeneration::gc_epilogue(full);
 105 }
 106 
 107 
 108 bool TenuredGeneration::should_collect(bool  full,
 109                                        size_t size,
 110                                        bool   is_tlab) {
 111   // This should be one big conditional or (||), but I want to be able to tell
 112   // why it returns what it returns (without re-evaluating the conditionals
 113   // in case they aren't idempotent), so I'm doing it this way.
 114   // DeMorgan says it's okay.
 115   bool result = false;
 116   if (!result && full) {
 117     result = true;
 118     if (PrintGC && Verbose) {
 119       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 120                     " full");
 121     }
 122   }
 123   if (!result && should_allocate(size, is_tlab)) {
 124     result = true;
 125     if (PrintGC && Verbose) {
 126       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 127                     " should_allocate(" SIZE_FORMAT ")",
 128                     size);
 129     }
 130   }
 131   // If we don't have very much free space.
 132   // XXX: 10000 should be a percentage of the capacity!!!
 133   if (!result && free() < 10000) {
 134     result = true;
 135     if (PrintGC && Verbose) {
 136       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 137                     " free(): " SIZE_FORMAT,
 138                     free());
 139     }
 140   }
 141   // If we had to expand to accomodate promotions from younger generations
 142   if (!result && _capacity_at_prologue < capacity()) {
 143     result = true;
 144     if (PrintGC && Verbose) {
 145       gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
 146                     "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
 147                     _capacity_at_prologue, capacity());
 148     }
 149   }
 150   return result;
 151 }
 152 
 153 void TenuredGeneration::collect(bool   full,
 154                                 bool   clear_all_soft_refs,
 155                                 size_t size,
 156                                 bool   is_tlab) {
 157   retire_alloc_buffers_before_full_gc();
 158   OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
 159                                         size, is_tlab);
 160 }
 161 
 162 void TenuredGeneration::compute_new_size() {
 163   assert_locked_or_safepoint(Heap_lock);
 164 
 165   // Compute some numbers about the state of the heap.
 166   const size_t used_after_gc = used();
 167   const size_t capacity_after_gc = capacity();
 168 
 169   CardGeneration::compute_new_size();
 170 
 171   assert(used() == used_after_gc && used_after_gc <= capacity(),
 172          err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
 173          " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
 174 }
 175 void TenuredGeneration::update_gc_stats(int current_level,
 176                                         bool full) {
 177   // If the next lower level(s) has been collected, gather any statistics
 178   // that are of interest at this point.
 179   if (!full && (current_level + 1) == level()) {
 180     // Calculate size of data promoted from the younger generations
 181     // before doing the collection.
 182     size_t used_before_gc = used();
 183 
 184     // If the younger gen collections were skipped, then the
 185     // number of promoted bytes will be 0 and adding it to the
 186     // average will incorrectly lessen the average.  It is, however,
 187     // also possible that no promotion was needed.
 188     if (used_before_gc >= _used_at_prologue) {
 189       size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
 190       gc_stats()->avg_promoted()->sample(promoted_in_bytes);
 191     }
 192   }
 193 }
 194 
 195 void TenuredGeneration::update_counters() {
 196   if (UsePerfData) {
 197     _space_counters->update_all();
 198     _gen_counters->update_all();
 199   }
 200 }
 201 
 202 
 203 #if INCLUDE_ALL_GCS
 204 oop TenuredGeneration::par_promote(int thread_num,
 205                                    oop old, markOop m, size_t word_sz) {
 206 
 207   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 208   HeapWord* obj_ptr = buf->allocate(word_sz);
 209   bool is_lab = true;
 210   if (obj_ptr == NULL) {
 211 #ifndef PRODUCT
 212     if (Universe::heap()->promotion_should_fail()) {
 213       return NULL;
 214     }
 215 #endif  // #ifndef PRODUCT
 216 
 217     // Slow path:
 218     if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {
 219       // Is small enough; abandon this buffer and start a new one.
 220       size_t buf_size = buf->word_sz();
 221       HeapWord* buf_space =
 222         TenuredGeneration::par_allocate(buf_size, false);
 223       if (buf_space == NULL) {
 224         buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);
 225       }
 226       if (buf_space != NULL) {
 227         buf->retire(false, false);
 228         buf->set_buf(buf_space);
 229         obj_ptr = buf->allocate(word_sz);
 230         assert(obj_ptr != NULL, "Buffer was definitely big enough...");
 231       }
 232     };
 233     // Otherwise, buffer allocation failed; try allocating object
 234     // individually.
 235     if (obj_ptr == NULL) {
 236       obj_ptr = TenuredGeneration::par_allocate(word_sz, false);
 237       if (obj_ptr == NULL) {
 238         obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);
 239       }
 240     }
 241     if (obj_ptr == NULL) return NULL;
 242   }
 243   assert(obj_ptr != NULL, "program logic");
 244   Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);
 245   oop obj = oop(obj_ptr);
 246   // Restore the mark word copied above.
 247   obj->set_mark(m);
 248   return obj;
 249 }
 250 
 251 void TenuredGeneration::par_promote_alloc_undo(int thread_num,
 252                                                HeapWord* obj,
 253                                                size_t word_sz) {
 254   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 255   if (buf->contains(obj)) {
 256     guarantee(buf->contains(obj + word_sz - 1),
 257               "should contain whole object");
 258     buf->undo_allocation(obj, word_sz);
 259   } else {
 260     CollectedHeap::fill_with_object(obj, word_sz);
 261   }
 262 }
 263 
 264 void TenuredGeneration::par_promote_alloc_done(int thread_num) {
 265   ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
 266   buf->retire(true, ParallelGCRetainPLAB);
 267 }
 268 
 269 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {
 270   if (UseParNewGC) {
 271     for (uint i = 0; i < ParallelGCThreads; i++) {
 272       _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);
 273     }
 274   }
 275 }
 276 
 277 // Verify that any retained parallel allocation buffers do not
 278 // intersect with dirty cards.
 279 void TenuredGeneration::verify_alloc_buffers_clean() {
 280   if (UseParNewGC) {
 281     for (uint i = 0; i < ParallelGCThreads; i++) {
 282       _rs->verify_aligned_region_empty(_alloc_buffers[i]->range());
 283     }
 284   }
 285 }
 286 
 287 #else  // INCLUDE_ALL_GCS
 288 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}
 289 void TenuredGeneration::verify_alloc_buffers_clean() {}
 290 #endif // INCLUDE_ALL_GCS
 291 
 292 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
 293   size_t available = max_contiguous_available();
 294   size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();
 295   bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);
 296   if (PrintGC && Verbose) {
 297     gclog_or_tty->print_cr(
 298       "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
 299       "max_promo("SIZE_FORMAT")",
 300       res? "":" not", available, res? ">=":"<",
 301       av_promo, max_promotion_in_bytes);
 302   }
 303   return res;
 304 }