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