1 /*
2 * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "memory/allocation.hpp"
25 #include "gc/shenandoah/brooksPointer.hpp"
26 #include "gc/shenandoah/shenandoahConnectionMatrix.hpp"
27 #include "gc/shenandoah/shenandoahHeap.hpp"
28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
30 #include "gc/shared/space.inline.hpp"
31 #include "memory/universe.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/mutexLocker.hpp"
34 #include "runtime/os.hpp"
35 #include "runtime/safepoint.hpp"
36
37 Monitor ShenandoahHeapRegion::_mem_protect_lock(Mutex::special, "ShenandoahMemProtect_lock", true, Monitor::_safepoint_check_never);
38 size_t ShenandoahHeapRegion::RegionSizeShift = 0;
39 size_t ShenandoahHeapRegion::RegionSizeBytes = 0;
40
41 ShenandoahHeapRegion::ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start,
42 size_t regionSizeWords, size_t index) :
43 #ifdef ASSERT
44 _mem_protection_level(0),
45 #endif
46 _heap(heap),
47 _region_number(index),
48 _live_data(0),
49 reserved(MemRegion(start, regionSizeWords)),
50 _humongous_start(false),
51 _humongous_continuation(false),
52 _humongous_obj_array(false),
53 _recycled(true),
54 _root(false),
55 _new_top(NULL),
56 _critical_pins(0) {
57
58 ContiguousSpace::initialize(reserved, true, false);
59 }
60
61 size_t ShenandoahHeapRegion::region_number() const {
62 return _region_number;
63 }
64
65 bool ShenandoahHeapRegion::rollback_allocation(uint size) {
66 set_top(top() - size);
67 return true;
68 }
69
70 void ShenandoahHeapRegion::clear_live_data() {
71 assert(Thread::current()->is_VM_thread(), "by VM thread");
72 _live_data = 0;
73 }
74
75 void ShenandoahHeapRegion::set_recently_allocated(bool value) {
76 _recycled = value;
77 }
78
79 bool ShenandoahHeapRegion::is_recently_allocated() const {
80 return _recycled && used() > 0;
81 }
82
83 void ShenandoahHeapRegion::set_live_data(size_t s) {
84 assert(Thread::current()->is_VM_thread(), "by VM thread");
85 _live_data = (jint) (s / HeapWordSize);
86 }
87
88 size_t ShenandoahHeapRegion::get_live_data_words() const {
89 return (size_t)OrderAccess::load_acquire((volatile jint*)&_live_data);
90 }
91
92 size_t ShenandoahHeapRegion::get_live_data_bytes() const {
93 return get_live_data_words() * HeapWordSize;
94 }
95
96 bool ShenandoahHeapRegion::has_live() const {
97 return get_live_data_words() != 0;
98 }
99
100 size_t ShenandoahHeapRegion::garbage() const {
101 assert(used() >= get_live_data_bytes() || is_humongous(), "Live Data must be a subset of used() live: "SIZE_FORMAT" used: "SIZE_FORMAT,
102 get_live_data_bytes(), used());
103 size_t result = used() - get_live_data_bytes();
104 return result;
105 }
106
107 bool ShenandoahHeapRegion::in_collection_set() const {
108 return _heap->region_in_collection_set(_region_number);
109 }
110
111 void ShenandoahHeapRegion::set_in_collection_set(bool b) {
112 assert(! (is_humongous() && b), "never ever enter a humongous region into the collection set");
113
114 _heap->set_region_in_collection_set(_region_number, b);
115
116 #ifdef ASSERT
117 if (ShenandoahVerifyWritesToFromSpace || ShenandoahVerifyReadsToFromSpace) {
118 if (b) {
119 memProtectionOn();
120 assert(_mem_protection_level == 0, "need to be protected here");
121 } else {
122 assert(_mem_protection_level == 0, "need to be protected here");
123 memProtectionOff();
124 }
125 }
126 #endif
127 }
128
129 #include <sys/mman.h>
130
131 #ifdef ASSERT
132
133 void ShenandoahHeapRegion::memProtectionOn() {
134 /*
135 log_develop_trace(gc)("Protect memory on region level: "INT32_FORMAT, _mem_protection_level);
136 print(tty);
137 */
138 MutexLockerEx ml(&_mem_protect_lock, true);
139 assert(_mem_protection_level >= 1, "invariant");
140
141 if (--_mem_protection_level == 0) {
142 if (ShenandoahVerifyWritesToFromSpace) {
143 assert(! ShenandoahVerifyReadsToFromSpace, "can't verify from-space reads when verifying from-space writes");
144 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_READ);
145 } else {
146 assert(ShenandoahVerifyReadsToFromSpace, "need to be verifying reads here");
147 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_NONE);
148 }
149 }
150 }
151
152 void ShenandoahHeapRegion::memProtectionOff() {
153 /*
154 tty->print_cr("unprotect memory on region level: "INT32_FORMAT, _mem_protection_level);
155 print(tty);
156 */
157 MutexLockerEx ml(&_mem_protect_lock, true);
158 assert(_mem_protection_level >= 0, "invariant");
159 if (_mem_protection_level++ == 0) {
160 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_RW);
161 }
162 }
163
164 #endif
165
166 void ShenandoahHeapRegion::print_on(outputStream* st) const {
167 st->print("ShenandoahHeapRegion: "PTR_FORMAT"/"SIZE_FORMAT, p2i(this), _region_number);
168
169 if (in_collection_set())
170 st->print("C");
171 if (is_humongous_start()) {
172 st->print("H");
173 }
174 if (is_humongous_continuation()) {
175 st->print("h");
176 }
177 //else
178 st->print(" ");
179
180 st->print_cr("live = "SIZE_FORMAT" garbage = "SIZE_FORMAT" bottom = "PTR_FORMAT" end = "PTR_FORMAT" top = "PTR_FORMAT,
181 get_live_data_bytes(), garbage(), p2i(bottom()), p2i(end()), p2i(top()));
182 }
183
184
185 void ShenandoahHeapRegion::object_iterate_interruptible(ObjectClosure* blk, bool allow_cancel) {
186 HeapWord* p = bottom() + BrooksPointer::word_size();
187 while (p < top() && !(allow_cancel && _heap->cancelled_concgc())) {
188 blk->do_object(oop(p));
189 #ifdef ASSERT
190 if (ShenandoahVerifyReadsToFromSpace) {
191 memProtectionOff();
192 p += oop(p)->size() + BrooksPointer::word_size();
193 memProtectionOn();
194 } else {
195 p += oop(p)->size() + BrooksPointer::word_size();
196 }
197 #else
198 p += oop(p)->size() + BrooksPointer::word_size();
199 #endif
200 }
201 }
202
203 HeapWord* ShenandoahHeapRegion::object_iterate_careful(ObjectClosureCareful* blk) {
204 HeapWord * limit = concurrent_iteration_safe_limit();
205 assert(limit <= top(), "sanity check");
206 for (HeapWord* p = bottom() + BrooksPointer::word_size(); p < limit;) {
207 size_t size = blk->do_object_careful(oop(p));
208 if (size == 0) {
209 return p; // failed at p
210 } else {
211 p += size + BrooksPointer::word_size();
212 }
213 }
214 return NULL; // all done
215 }
216
217 void ShenandoahHeapRegion::oop_iterate(ExtendedOopClosure* blk) {
218 if (is_empty()) return;
219 if (is_humongous_obj_array()) {
220 oop_iterate_humongous(blk);
221 } else {
222 oop_iterate_objects(blk);
223 }
224 }
225
226 void ShenandoahHeapRegion::oop_iterate_objects(ExtendedOopClosure* blk) {
227 assert(! is_humongous_obj_array(), "no humongous obj array here");
228 assert(! is_humongous_continuation(), "no humongous continuation here");
229 // Note: it is ok to have a humongous start region here, e.g. in the case
230 // of an int[]. We might want to visit its header.
231 HeapWord* obj_addr = bottom() + BrooksPointer::word_size();
232 HeapWord* t = top();
233 // Could call objects iterate, but this is easier.
234 while (obj_addr < t) {
235 oop obj = oop(obj_addr);
236 obj_addr += obj->oop_iterate_size(blk) + BrooksPointer::word_size();
237 }
238 }
239
240 void ShenandoahHeapRegion::oop_iterate_humongous(ExtendedOopClosure* blk) {
241 assert(is_humongous_obj_array(), "only humongous obj array here");
242 // Find head.
243 ShenandoahHeapRegionSet* regions = _heap->regions();
244 uint idx = region_number();
245 ShenandoahHeapRegion* r = regions->get(idx);
246 while (! r->is_humongous_start()) {
247 idx--;
248 r = regions->get(idx);
249 }
250 assert(r->is_humongous_start(), "need humongous head here");
251 objArrayOop array = objArrayOop(r->bottom() + BrooksPointer::word_size());
252 array->oop_iterate(blk, MemRegion(bottom(), top()));
253 }
254
255 void ShenandoahHeapRegion::fill_region() {
256 ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap();
257
258 if (free() > (BrooksPointer::word_size() + CollectedHeap::min_fill_size())) {
259 HeapWord* filler = allocate(BrooksPointer::word_size());
260 HeapWord* obj = allocate(end() - top());
261 sh->fill_with_object(obj, end() - obj);
262 BrooksPointer::initialize(oop(obj));
263 }
264 }
265
266 void ShenandoahHeapRegion::set_humongous_start(bool start) {
267 _humongous_start = start;
268 }
269
270 void ShenandoahHeapRegion::set_humongous_continuation(bool continuation) {
271 _humongous_continuation = continuation;
272 }
273
274 void ShenandoahHeapRegion::set_humongous_obj_array(bool obj_array) {
275 _humongous_obj_array = obj_array;
276 }
277
278 bool ShenandoahHeapRegion::is_humongous() const {
279 return _humongous_start || _humongous_continuation;
280 }
281
282 bool ShenandoahHeapRegion::is_humongous_start() const {
283 return _humongous_start;
284 }
285
286 bool ShenandoahHeapRegion::is_humongous_continuation() const {
287 return _humongous_continuation;
288 }
289
290 bool ShenandoahHeapRegion::is_humongous_obj_array() const {
291 return _humongous_continuation;
292 }
293
294 void ShenandoahHeapRegion::recycle() {
295 ContiguousSpace::initialize(reserved, true, false);
296 clear_live_data();
297 _humongous_start = false;
298 _humongous_continuation = false;
299 _humongous_obj_array = false;
300 _recycled = true;
301 _root = false;
302 set_in_collection_set(false);
303 // Reset C-TAMS pointer to ensure size-based iteration, everything
304 // in that regions is going to be new objects.
305 _heap->set_complete_top_at_mark_start(bottom(), bottom());
306 // We can only safely reset the C-TAMS pointer if the bitmap is clear for that region.
307 assert(_heap->is_complete_bitmap_clear_range(bottom(), end()), "must be clear");
308 _heap->connection_matrix()->clear_region(region_number());
309 }
310
311 HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const {
312 assert(MemRegion(bottom(), end()).contains(p),
313 "p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
314 p2i(p), p2i(bottom()), p2i(end()));
315 if (p >= top()) {
316 return top();
317 } else {
318 HeapWord* last = bottom() + BrooksPointer::word_size();
319 HeapWord* cur = last;
320 while (cur <= p) {
321 last = cur;
322 cur += oop(cur)->size() + BrooksPointer::word_size();
323 }
324 assert(oop(last)->is_oop(),
325 PTR_FORMAT" should be an object start", p2i(last));
326 return last;
327 }
328 }
329
330 void ShenandoahHeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
331 // Absolute minimums we should not ever break:
332 static const size_t MIN_REGION_SIZE = 256*K;
333 static const size_t MIN_NUM_REGIONS = 10;
334
335 uintx region_size;
336 if (FLAG_IS_DEFAULT(ShenandoahHeapRegionSize)) {
337 if (ShenandoahMinRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
338 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
339 "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "K).",
340 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahMinRegionSize/K);
341 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
342 }
343 if (ShenandoahMinRegionSize < MIN_REGION_SIZE) {
344 err_msg message("" SIZE_FORMAT "K should not be lower than minimum region size (" SIZE_FORMAT "K).",
345 ShenandoahMinRegionSize/K, MIN_REGION_SIZE/K);
346 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
347 }
348 if (ShenandoahMinRegionSize < MinTLABSize) {
349 err_msg message("" SIZE_FORMAT "K should not be lower than TLAB size size (" SIZE_FORMAT "K).",
350 ShenandoahMinRegionSize/K, MinTLABSize/K);
351 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
352 }
353 if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) {
354 err_msg message("" SIZE_FORMAT "K should not be lower than min region size (" SIZE_FORMAT "K).",
355 ShenandoahMaxRegionSize/K, MIN_REGION_SIZE/K);
356 vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message);
357 }
358 if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) {
359 err_msg message("Minimum (" SIZE_FORMAT "K) should be larger than maximum (" SIZE_FORMAT "K).",
360 ShenandoahMinRegionSize/K, ShenandoahMaxRegionSize/K);
361 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message);
362 }
363 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
364 region_size = MAX2(average_heap_size / ShenandoahTargetNumRegions,
365 ShenandoahMinRegionSize);
366
367 // Now make sure that we don't go over or under our limits.
368 region_size = MAX2(ShenandoahMinRegionSize, region_size);
369 region_size = MIN2(ShenandoahMaxRegionSize, region_size);
370
371 } else {
372 if (ShenandoahHeapRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
373 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
374 "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "K).",
375 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahHeapRegionSize/K);
376 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
377 }
378 if (ShenandoahHeapRegionSize < ShenandoahMinRegionSize) {
379 err_msg message("Heap region size (" SIZE_FORMAT "K) should be larger than min region size (" SIZE_FORMAT "K).",
380 ShenandoahHeapRegionSize/K, ShenandoahMinRegionSize/K);
381 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
382 }
383 if (ShenandoahHeapRegionSize > ShenandoahMaxRegionSize) {
384 err_msg message("Heap region size (" SIZE_FORMAT "K) should be lower than max region size (" SIZE_FORMAT "K).",
385 ShenandoahHeapRegionSize/K, ShenandoahMaxRegionSize/K);
386 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
387 }
388 region_size = ShenandoahHeapRegionSize;
389 }
390
391 // Make sure region size is at least one large page, if enabled.
392 // Otherwise, mem-protecting one region may falsely protect the adjacent
393 // regions too.
394 if (UseLargePages) {
395 region_size = MAX2(region_size, os::large_page_size());
396 }
397
398 int region_size_log = log2_long((jlong) region_size);
399 // Recalculate the region size to make sure it's a power of
400 // 2. This means that region_size is the largest power of 2 that's
401 // <= what we've calculated so far.
402 region_size = ((uintx)1 << region_size_log);
403
404 // Now, set up the globals.
405 guarantee(RegionSizeShift == 0, "we should only set it once");
406 RegionSizeShift = region_size_log;
407
408 guarantee(RegionSizeBytes == 0, "we should only set it once");
409 RegionSizeBytes = (size_t)region_size;
410
411 log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", RegionSizeBytes / M);
412 log_info(gc, init)("Region size in bytes: "SIZE_FORMAT, RegionSizeBytes);
413 log_info(gc, init)("Region size shift: "SIZE_FORMAT, RegionSizeShift);
414 log_info(gc, init)("Initial number of regions: "SIZE_FORMAT, initial_heap_size / RegionSizeBytes);
415 log_info(gc, init)("Maximum number of regions: "SIZE_FORMAT, max_heap_size / RegionSizeBytes);
416 }
417
418 CompactibleSpace* ShenandoahHeapRegion::next_compaction_space() const {
419 return _heap->next_compaction_region(this);
420 }
421
422 void ShenandoahHeapRegion::prepare_for_compaction(CompactPoint* cp) {
423 scan_and_forward(this, cp);
424 }
425
426 void ShenandoahHeapRegion::adjust_pointers() {
427 // Check first is there is any work to do.
428 if (used() == 0) {
429 return; // Nothing to do.
430 }
431
432 scan_and_adjust_pointers(this);
433 }
434
435 void ShenandoahHeapRegion::compact() {
436 assert(!is_humongous(), "Shouldn't be compacting humongous regions");
437 scan_and_compact(this);
438 }
439
440 void ShenandoahHeapRegion::pin() {
441 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
442 assert(_critical_pins >= 0, "sanity");
443 Atomic::inc(&_critical_pins);
444 }
445
446 void ShenandoahHeapRegion::unpin() {
447 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
448 Atomic::dec(&_critical_pins);
449 assert(_critical_pins >= 0, "sanity");
450 }
451
452 bool ShenandoahHeapRegion::is_pinned() {
453 jint v = OrderAccess::load_acquire(&_critical_pins);
454 assert(v >= 0, "sanity");
455 return v > 0;
456 }