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