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/serial/genMarkSweep.hpp" 27 #include "gc/serial/tenuredGeneration.inline.hpp" 28 #include "gc/shared/blockOffsetTable.inline.hpp" 29 #include "gc/shared/cardGeneration.inline.hpp" 30 #include "gc/shared/collectorCounters.hpp" 31 #include "gc/shared/gcTimer.hpp" 32 #include "gc/shared/genOopClosures.inline.hpp" 33 #include "gc/shared/generationSpec.hpp" 34 #include "gc/shared/space.hpp" 35 #include "logging/log.hpp" 36 #include "memory/allocation.inline.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/java.hpp" 39 #include "utilities/macros.hpp" 40 #if INCLUDE_ALL_GCS 41 #include "gc/cms/parOopClosures.hpp" 42 #endif 43 44 TenuredGeneration::TenuredGeneration(ReservedSpace rs, 45 size_t initial_byte_size, 46 CardTableRS* remset) : 47 CardGeneration(rs, initial_byte_size, remset) 48 { 49 HeapWord* bottom = (HeapWord*) _virtual_space.low(); 50 HeapWord* end = (HeapWord*) _virtual_space.high(); 51 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end)); 52 _the_space->reset_saved_mark(); 53 _shrink_factor = 0; 54 _capacity_at_prologue = 0; 55 56 _gc_stats = new GCStats(); 57 58 // initialize performance counters 59 60 const char* gen_name = "old"; 61 GenCollectorPolicy* gcp = GenCollectedHeap::heap()->gen_policy(); 62 // Generation Counters -- generation 1, 1 subspace 63 _gen_counters = new GenerationCounters(gen_name, 1, 1, 64 gcp->min_old_size(), gcp->max_old_size(), &_virtual_space); 65 66 _gc_counters = new CollectorCounters("MSC", 1); 67 68 _space_counters = new CSpaceCounters(gen_name, 0, 69 _virtual_space.reserved_size(), 70 _the_space, _gen_counters); 71 } 72 73 void TenuredGeneration::gc_prologue(bool full) { 74 _capacity_at_prologue = capacity(); 75 _used_at_prologue = used(); 76 } 77 78 bool TenuredGeneration::should_collect(bool full, 79 size_t size, 80 bool is_tlab) { 81 // This should be one big conditional or (||), but I want to be able to tell 82 // why it returns what it returns (without re-evaluating the conditionals 83 // in case they aren't idempotent), so I'm doing it this way. 84 // DeMorgan says it's okay. 85 if (full) { 86 log_trace(gc)("TenuredGeneration::should_collect: because full"); 87 return true; 88 } 89 if (should_allocate(size, is_tlab)) { 90 log_trace(gc)("TenuredGeneration::should_collect: because should_allocate(" SIZE_FORMAT ")", size); 91 return true; 92 } 93 // If we don't have very much free space. 94 // XXX: 10000 should be a percentage of the capacity!!! 95 if (free() < 10000) { 96 log_trace(gc)("TenuredGeneration::should_collect: because free(): " SIZE_FORMAT, free()); 97 return true; 98 } 99 // If we had to expand to accommodate promotions from the young generation 100 if (_capacity_at_prologue < capacity()) { 101 log_trace(gc)("TenuredGeneration::should_collect: because_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT, 102 _capacity_at_prologue, capacity()); 103 return true; 104 } 105 106 return false; 107 } 108 109 void TenuredGeneration::compute_new_size() { 110 assert_locked_or_safepoint(Heap_lock); 111 112 // Compute some numbers about the state of the heap. 113 const size_t used_after_gc = used(); 114 const size_t capacity_after_gc = capacity(); 115 116 CardGeneration::compute_new_size(); 117 118 assert(used() == used_after_gc && used_after_gc <= capacity(), 119 "used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT 120 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()); 121 } 122 123 void TenuredGeneration::update_gc_stats(Generation* current_generation, 124 bool full) { 125 // If the young generation has been collected, gather any statistics 126 // that are of interest at this point. 127 bool current_is_young = GenCollectedHeap::heap()->is_young_gen(current_generation); 128 if (!full && current_is_young) { 129 // Calculate size of data promoted from the young generation 130 // before doing the collection. 131 size_t used_before_gc = used(); 132 133 // If the young gen collection was skipped, then the 134 // number of promoted bytes will be 0 and adding it to the 135 // average will incorrectly lessen the average. It is, however, 136 // also possible that no promotion was needed. 137 if (used_before_gc >= _used_at_prologue) { 138 size_t promoted_in_bytes = used_before_gc - _used_at_prologue; 139 gc_stats()->avg_promoted()->sample(promoted_in_bytes); 140 } 141 } 142 } 143 144 void TenuredGeneration::update_counters() { 145 if (UsePerfData) { 146 _space_counters->update_all(); 147 _gen_counters->update_all(); 148 } 149 } 150 151 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const { 152 size_t available = max_contiguous_available(); 153 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average(); 154 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes); 155 156 log_trace(gc)("Tenured: promo attempt is%s safe: available(" SIZE_FORMAT ") %s av_promo(" SIZE_FORMAT "), max_promo(" SIZE_FORMAT ")", 157 res? "":" not", available, res? ">=":"<", av_promo, max_promotion_in_bytes); 158 159 return res; 160 } 161 162 void TenuredGeneration::collect(bool full, 163 bool clear_all_soft_refs, 164 size_t size, 165 bool is_tlab) { 166 GenCollectedHeap* gch = GenCollectedHeap::heap(); 167 168 // Temporarily expand the span of our ref processor, so 169 // refs discovery is over the entire heap, not just this generation 170 ReferenceProcessorSpanMutator 171 x(ref_processor(), gch->reserved_region()); 172 173 STWGCTimer* gc_timer = GenMarkSweep::gc_timer(); 174 gc_timer->register_gc_start(); 175 176 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer(); 177 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start()); 178 179 gch->pre_full_gc_dump(gc_timer); 180 181 GenMarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs); 182 183 gch->post_full_gc_dump(gc_timer); 184 185 gc_timer->register_gc_end(); 186 187 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions()); 188 } 189 190 HeapWord* 191 TenuredGeneration::expand_and_allocate(size_t word_size, 192 bool is_tlab, 193 bool parallel) { 194 assert(!is_tlab, "TenuredGeneration does not support TLAB allocation"); 195 if (parallel) { 196 MutexLocker x(ParGCRareEvent_lock); 197 HeapWord* result = NULL; 198 size_t byte_size = word_size * HeapWordSize; 199 while (true) { 200 expand(byte_size, _min_heap_delta_bytes); 201 if (GCExpandToAllocateDelayMillis > 0) { 202 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false); 203 } 204 result = _the_space->par_allocate(word_size); 205 if ( result != NULL) { 206 return result; 207 } else { 208 // If there's not enough expansion space available, give up. 209 if (_virtual_space.uncommitted_size() < byte_size) { 210 return NULL; 211 } 212 // else try again 213 } 214 } 215 } else { 216 expand(word_size*HeapWordSize, _min_heap_delta_bytes); 217 return _the_space->allocate(word_size); 218 } 219 } 220 221 bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) { 222 GCMutexLocker x(ExpandHeap_lock); 223 return CardGeneration::expand(bytes, expand_bytes); 224 } 225 226 size_t TenuredGeneration::unsafe_max_alloc_nogc() const { 227 return _the_space->free(); 228 } 229 230 size_t TenuredGeneration::contiguous_available() const { 231 return _the_space->free() + _virtual_space.uncommitted_size(); 232 } 233 234 void TenuredGeneration::assert_correct_size_change_locking() { 235 assert_locked_or_safepoint(ExpandHeap_lock); 236 } 237 238 // Currently nothing to do. 239 void TenuredGeneration::prepare_for_verify() {} 240 241 void TenuredGeneration::object_iterate(ObjectClosure* blk) { 242 _the_space->object_iterate(blk); 243 } 244 245 void TenuredGeneration::save_marks() { 246 _the_space->set_saved_mark(); 247 } 248 249 void TenuredGeneration::reset_saved_marks() { 250 _the_space->reset_saved_mark(); 251 } 252 253 bool TenuredGeneration::no_allocs_since_save_marks() { 254 return _the_space->saved_mark_at_top(); 255 } 256 257 #define TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 258 \ 259 void TenuredGeneration:: \ 260 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 261 blk->set_generation(this); \ 262 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \ 263 blk->reset_generation(); \ 264 save_marks(); \ 265 } 266 267 ALL_SINCE_SAVE_MARKS_CLOSURES(TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN) 268 269 #undef TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN 270 271 void TenuredGeneration::gc_epilogue(bool full) { 272 // update the generation and space performance counters 273 update_counters(); 274 if (ZapUnusedHeapArea) { 275 _the_space->check_mangled_unused_area_complete(); 276 } 277 } 278 279 void TenuredGeneration::record_spaces_top() { 280 assert(ZapUnusedHeapArea, "Not mangling unused space"); 281 _the_space->set_top_for_allocations(); 282 } 283 284 void TenuredGeneration::verify() { 285 _the_space->verify(); 286 } 287 288 void TenuredGeneration::print_on(outputStream* st) const { 289 Generation::print_on(st); 290 st->print(" the"); 291 _the_space->print_on(st); 292 }