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