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/gcTimer.hpp"
28 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/blockOffsetTable.inline.hpp"
31 #include "memory/generationSpec.hpp"
32 #include "memory/genMarkSweep.hpp"
33 #include "memory/genOopClosures.inline.hpp"
34 #include "memory/space.hpp"
35 #include "memory/tenuredGeneration.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/java.hpp"
38 #include "utilities/macros.hpp"
39
40 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
41 size_t initial_byte_size, int level,
42 GenRemSet* remset) :
43 CardGeneration(rs, initial_byte_size, level, remset)
44 {
45 HeapWord* bottom = (HeapWord*) _virtual_space.low();
46 HeapWord* end = (HeapWord*) _virtual_space.high();
47 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
48 _the_space->reset_saved_mark();
49 _shrink_factor = 0;
50 _capacity_at_prologue = 0;
51
52 _gc_stats = new GCStats();
53
54 // initialize performance counters
55
56 const char* gen_name = "old";
57 GenCollectorPolicy* gcp = (GenCollectorPolicy*) GenCollectedHeap::heap()->collector_policy();
58
59 // Generation Counters -- generation 1, 1 subspace
60 _gen_counters = new GenerationCounters(gen_name, 1, 1,
61 gcp->min_old_size(), gcp->max_old_size(), &_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 }
69
70 void TenuredGeneration::gc_prologue(bool full) {
71 _capacity_at_prologue = capacity();
72 _used_at_prologue = used();
73 }
74
75 bool TenuredGeneration::should_collect(bool full,
76 size_t size,
77 bool is_tlab) {
78 // This should be one big conditional or (||), but I want to be able to tell
79 // why it returns what it returns (without re-evaluating the conditionals
80 // in case they aren't idempotent), so I'm doing it this way.
81 // DeMorgan says it's okay.
82 bool result = false;
83 if (!result && full) {
84 result = true;
85 if (PrintGC && Verbose) {
86 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
87 " full");
88 }
89 }
90 if (!result && should_allocate(size, is_tlab)) {
91 result = true;
92 if (PrintGC && Verbose) {
93 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
94 " should_allocate(" SIZE_FORMAT ")",
95 size);
96 }
97 }
98 // If we don't have very much free space.
99 // XXX: 10000 should be a percentage of the capacity!!!
100 if (!result && free() < 10000) {
101 result = true;
102 if (PrintGC && Verbose) {
103 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
104 " free(): " SIZE_FORMAT,
105 free());
106 }
107 }
108 // If we had to expand to accommodate promotions from younger generations
109 if (!result && _capacity_at_prologue < capacity()) {
110 result = true;
111 if (PrintGC && Verbose) {
112 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
113 "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
114 _capacity_at_prologue, capacity());
115 }
116 }
117 return result;
118 }
119
120 void TenuredGeneration::compute_new_size() {
121 assert_locked_or_safepoint(Heap_lock);
122
123 // Compute some numbers about the state of the heap.
124 const size_t used_after_gc = used();
125 const size_t capacity_after_gc = capacity();
126
127 CardGeneration::compute_new_size();
128
129 assert(used() == used_after_gc && used_after_gc <= capacity(),
130 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
131 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
132 }
133
134 void TenuredGeneration::update_gc_stats(int current_level,
135 bool full) {
136 // If the next lower level(s) has been collected, gather any statistics
137 // that are of interest at this point.
138 if (!full && (current_level + 1) == level()) {
139 // Calculate size of data promoted from the younger generations
140 // before doing the collection.
141 size_t used_before_gc = used();
142
143 // If the younger gen collections were skipped, then the
144 // number of promoted bytes will be 0 and adding it to the
145 // average will incorrectly lessen the average. It is, however,
146 // also possible that no promotion was needed.
147 if (used_before_gc >= _used_at_prologue) {
148 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
149 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
150 }
151 }
152 }
153
154 void TenuredGeneration::update_counters() {
155 if (UsePerfData) {
156 _space_counters->update_all();
157 _gen_counters->update_all();
158 }
159 }
160
161 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
162 size_t available = max_contiguous_available();
163 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average();
164 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes);
165 if (PrintGC && Verbose) {
166 gclog_or_tty->print_cr(
167 "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
168 "max_promo("SIZE_FORMAT")",
169 res? "":" not", available, res? ">=":"<",
170 av_promo, max_promotion_in_bytes);
171 }
172 return res;
173 }
174
175 void TenuredGeneration::collect(bool full,
176 bool clear_all_soft_refs,
177 size_t size,
178 bool is_tlab) {
179 GenCollectedHeap* gch = GenCollectedHeap::heap();
180
181 SpecializationStats::clear();
182 // Temporarily expand the span of our ref processor, so
183 // refs discovery is over the entire heap, not just this generation
184 ReferenceProcessorSpanMutator
185 x(ref_processor(), gch->reserved_region());
186
187 STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
188 gc_timer->register_gc_start();
189
190 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
191 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
192
193 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
194
195 gc_timer->register_gc_end();
196
197 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
198
199 SpecializationStats::print();
200 }
201
202 HeapWord*
203 TenuredGeneration::expand_and_allocate(size_t word_size,
204 bool is_tlab,
205 bool parallel) {
206 assert(!is_tlab, "TenuredGeneration does not support TLAB allocation");
207 if (parallel) {
208 MutexLocker x(ParGCRareEvent_lock);
209 HeapWord* result = NULL;
210 size_t byte_size = word_size * HeapWordSize;
211 while (true) {
212 expand(byte_size, _min_heap_delta_bytes);
213 if (GCExpandToAllocateDelayMillis > 0) {
214 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
215 }
216 result = _the_space->par_allocate(word_size);
217 if ( result != NULL) {
218 return result;
219 } else {
220 // If there's not enough expansion space available, give up.
221 if (_virtual_space.uncommitted_size() < byte_size) {
222 return NULL;
223 }
224 // else try again
225 }
226 }
227 } else {
228 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
229 return _the_space->allocate(word_size);
230 }
231 }
232
233 bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) {
234 GCMutexLocker x(ExpandHeap_lock);
235 return CardGeneration::expand(bytes, expand_bytes);
236 }
237
238
239 void TenuredGeneration::shrink(size_t bytes) {
240 assert_locked_or_safepoint(ExpandHeap_lock);
241 size_t size = ReservedSpace::page_align_size_down(bytes);
242 if (size > 0) {
243 shrink_by(size);
244 }
245 }
246
247
248 size_t TenuredGeneration::capacity() const {
249 return _the_space->capacity();
250 }
251
252
253 size_t TenuredGeneration::used() const {
254 return _the_space->used();
255 }
256
257
258 size_t TenuredGeneration::free() const {
259 return _the_space->free();
260 }
261
262 MemRegion TenuredGeneration::used_region() const {
263 return the_space()->used_region();
264 }
265
266 size_t TenuredGeneration::unsafe_max_alloc_nogc() const {
267 return _the_space->free();
268 }
269
270 size_t TenuredGeneration::contiguous_available() const {
271 return _the_space->free() + _virtual_space.uncommitted_size();
272 }
273
274 bool TenuredGeneration::grow_by(size_t bytes) {
275 assert_locked_or_safepoint(ExpandHeap_lock);
276 bool result = _virtual_space.expand_by(bytes);
277 if (result) {
278 size_t new_word_size =
279 heap_word_size(_virtual_space.committed_size());
280 MemRegion mr(_the_space->bottom(), new_word_size);
281 // Expand card table
282 Universe::heap()->barrier_set()->resize_covered_region(mr);
283 // Expand shared block offset array
284 _bts->resize(new_word_size);
285
286 // Fix for bug #4668531
287 if (ZapUnusedHeapArea) {
288 MemRegion mangle_region(_the_space->end(),
289 (HeapWord*)_virtual_space.high());
290 SpaceMangler::mangle_region(mangle_region);
291 }
292
293 // Expand space -- also expands space's BOT
294 // (which uses (part of) shared array above)
295 _the_space->set_end((HeapWord*)_virtual_space.high());
296
297 // update the space and generation capacity counters
298 update_counters();
299
300 if (Verbose && PrintGC) {
301 size_t new_mem_size = _virtual_space.committed_size();
302 size_t old_mem_size = new_mem_size - bytes;
303 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
304 SIZE_FORMAT "K to " SIZE_FORMAT "K",
305 name(), old_mem_size/K, bytes/K, new_mem_size/K);
306 }
307 }
308 return result;
309 }
310
311
312 bool TenuredGeneration::grow_to_reserved() {
313 assert_locked_or_safepoint(ExpandHeap_lock);
314 bool success = true;
315 const size_t remaining_bytes = _virtual_space.uncommitted_size();
316 if (remaining_bytes > 0) {
317 success = grow_by(remaining_bytes);
318 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
319 }
320 return success;
321 }
322
323 void TenuredGeneration::shrink_by(size_t bytes) {
324 assert_locked_or_safepoint(ExpandHeap_lock);
325 // Shrink committed space
326 _virtual_space.shrink_by(bytes);
327 // Shrink space; this also shrinks the space's BOT
328 _the_space->set_end((HeapWord*) _virtual_space.high());
329 size_t new_word_size = heap_word_size(_the_space->capacity());
330 // Shrink the shared block offset array
331 _bts->resize(new_word_size);
332 MemRegion mr(_the_space->bottom(), new_word_size);
333 // Shrink the card table
334 Universe::heap()->barrier_set()->resize_covered_region(mr);
335
336 if (Verbose && PrintGC) {
337 size_t new_mem_size = _virtual_space.committed_size();
338 size_t old_mem_size = new_mem_size + bytes;
339 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
340 name(), old_mem_size/K, new_mem_size/K);
341 }
342 }
343
344 // Currently nothing to do.
345 void TenuredGeneration::prepare_for_verify() {}
346
347 void TenuredGeneration::object_iterate(ObjectClosure* blk) {
348 _the_space->object_iterate(blk);
349 }
350
351 void TenuredGeneration::space_iterate(SpaceClosure* blk,
352 bool usedOnly) {
353 blk->do_space(_the_space);
354 }
355
356 void TenuredGeneration::younger_refs_iterate(OopsInGenClosure* blk) {
357 blk->set_generation(this);
358 younger_refs_in_space_iterate(_the_space, blk);
359 blk->reset_generation();
360 }
361
362 void TenuredGeneration::save_marks() {
363 _the_space->set_saved_mark();
364 }
365
366
367 void TenuredGeneration::reset_saved_marks() {
368 _the_space->reset_saved_mark();
369 }
370
371
372 bool TenuredGeneration::no_allocs_since_save_marks() {
373 return _the_space->saved_mark_at_top();
374 }
375
376 #define TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
377 \
378 void TenuredGeneration:: \
379 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
380 blk->set_generation(this); \
381 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \
382 blk->reset_generation(); \
383 save_marks(); \
384 }
385
386 ALL_SINCE_SAVE_MARKS_CLOSURES(TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN)
387
388 #undef TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN
389
390
391 void TenuredGeneration::gc_epilogue(bool full) {
392 _last_gc = WaterMark(the_space(), the_space()->top());
393
394 // update the generation and space performance counters
395 update_counters();
396 if (ZapUnusedHeapArea) {
397 the_space()->check_mangled_unused_area_complete();
398 }
399 }
400
401 void TenuredGeneration::record_spaces_top() {
402 assert(ZapUnusedHeapArea, "Not mangling unused space");
403 the_space()->set_top_for_allocations();
404 }
405
406 void TenuredGeneration::verify() {
407 the_space()->verify();
408 }
409
410 void TenuredGeneration::print_on(outputStream* st) const {
411 Generation::print_on(st);
412 st->print(" the");
413 the_space()->print_on(st);
414 }