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/shenandoahHeap.hpp"
27 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
28 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
29 #include "gc/shared/space.inline.hpp"
30 #include "memory/universe.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/mutexLocker.hpp"
33 #include "runtime/os.hpp"
34 #include "runtime/safepoint.hpp"
35
36 Monitor ShenandoahHeapRegion::_mem_protect_lock(Mutex::special, "ShenandoahMemProtect_lock", true, Monitor::_safepoint_check_never);
37 size_t ShenandoahHeapRegion::RegionSizeShift = 0;
38 size_t ShenandoahHeapRegion::RegionSizeBytes = 0;
39
40 ShenandoahHeapRegion::ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start,
41 size_t regionSizeWords, size_t index) :
42 #ifdef ASSERT
43 _mem_protection_level(0),
44 #endif
45 _heap(heap),
46 _region_number(index),
47 _live_data(0),
48 reserved(MemRegion(start, regionSizeWords)),
49 _humongous_start(false),
50 _humongous_continuation(false),
51 _recycled(true),
52 _new_top(NULL),
53 _critical_pins(0) {
54
55 ContiguousSpace::initialize(reserved, true, false);
56 }
57
58 size_t ShenandoahHeapRegion::region_number() const {
59 return _region_number;
60 }
61
62 bool ShenandoahHeapRegion::rollback_allocation(uint size) {
63 set_top(top() - size);
64 return true;
65 }
66
67 void ShenandoahHeapRegion::clear_live_data() {
68 assert(Thread::current()->is_VM_thread(), "by VM thread");
69 _live_data = 0;
70 }
71
72 void ShenandoahHeapRegion::set_recently_allocated(bool value) {
73 _recycled = value;
74 }
75
76 bool ShenandoahHeapRegion::is_recently_allocated() const {
77 return _recycled && used() > 0;
78 }
79
80 void ShenandoahHeapRegion::set_live_data(size_t s) {
81 assert(Thread::current()->is_VM_thread(), "by VM thread");
82 _live_data = (jint) (s / HeapWordSize);
83 }
84
85 size_t ShenandoahHeapRegion::get_live_data_words() const {
86 return (size_t)OrderAccess::load_acquire((volatile jint*)&_live_data);
87 }
88
89 size_t ShenandoahHeapRegion::get_live_data_bytes() const {
90 return get_live_data_words() * HeapWordSize;
91 }
92
93 bool ShenandoahHeapRegion::has_live() const {
94 return get_live_data_words() != 0;
95 }
96
97 size_t ShenandoahHeapRegion::garbage() const {
98 assert(used() >= get_live_data_bytes() || is_humongous(), "Live Data must be a subset of used() live: "SIZE_FORMAT" used: "SIZE_FORMAT,
99 get_live_data_bytes(), used());
100 size_t result = used() - get_live_data_bytes();
101 return result;
102 }
103
104 bool ShenandoahHeapRegion::in_collection_set() const {
105 return _heap->region_in_collection_set(_region_number);
106 }
107
108 void ShenandoahHeapRegion::set_in_collection_set(bool b) {
109 assert(! (is_humongous() && b), "never ever enter a humongous region into the collection set");
110
111 _heap->set_region_in_collection_set(_region_number, b);
112
113 #ifdef ASSERT
114 if (ShenandoahVerifyWritesToFromSpace || ShenandoahVerifyReadsToFromSpace) {
115 if (b) {
116 memProtectionOn();
117 assert(_mem_protection_level == 0, "need to be protected here");
118 } else {
119 assert(_mem_protection_level == 0, "need to be protected here");
120 memProtectionOff();
121 }
122 }
123 #endif
124 }
125
126 #include <sys/mman.h>
127
128 #ifdef ASSERT
129
130 void ShenandoahHeapRegion::memProtectionOn() {
131 /*
132 log_develop_trace(gc)("Protect memory on region level: "INT32_FORMAT, _mem_protection_level);
133 print(tty);
134 */
135 MutexLockerEx ml(&_mem_protect_lock, true);
136 assert(_mem_protection_level >= 1, "invariant");
137
138 if (--_mem_protection_level == 0) {
139 if (ShenandoahVerifyWritesToFromSpace) {
140 assert(! ShenandoahVerifyReadsToFromSpace, "can't verify from-space reads when verifying from-space writes");
141 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_READ);
142 } else {
143 assert(ShenandoahVerifyReadsToFromSpace, "need to be verifying reads here");
144 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_NONE);
145 }
146 }
147 }
148
149 void ShenandoahHeapRegion::memProtectionOff() {
150 /*
151 tty->print_cr("unprotect memory on region level: "INT32_FORMAT, _mem_protection_level);
152 print(tty);
153 */
154 MutexLockerEx ml(&_mem_protect_lock, true);
155 assert(_mem_protection_level >= 0, "invariant");
156 if (_mem_protection_level++ == 0) {
157 os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_RW);
158 }
159 }
160
161 #endif
162
163 void ShenandoahHeapRegion::print_on(outputStream* st) const {
164 st->print("ShenandoahHeapRegion: "PTR_FORMAT"/"SIZE_FORMAT, p2i(this), _region_number);
165
166 if (in_collection_set())
167 st->print("C");
168 if (is_humongous_start()) {
169 st->print("H");
170 }
171 if (is_humongous_continuation()) {
172 st->print("h");
173 }
174 //else
175 st->print(" ");
176
177 st->print_cr("live = "SIZE_FORMAT" garbage = "SIZE_FORMAT" bottom = "PTR_FORMAT" end = "PTR_FORMAT" top = "PTR_FORMAT,
178 get_live_data_bytes(), garbage(), p2i(bottom()), p2i(end()), p2i(top()));
179 }
180
181
182 void ShenandoahHeapRegion::object_iterate_interruptible(ObjectClosure* blk, bool allow_cancel) {
183 HeapWord* p = bottom() + BrooksPointer::word_size();
184 while (p < top() && !(allow_cancel && _heap->cancelled_concgc())) {
185 blk->do_object(oop(p));
186 #ifdef ASSERT
187 if (ShenandoahVerifyReadsToFromSpace) {
188 memProtectionOff();
189 p += oop(p)->size() + BrooksPointer::word_size();
190 memProtectionOn();
191 } else {
192 p += oop(p)->size() + BrooksPointer::word_size();
193 }
194 #else
195 p += oop(p)->size() + BrooksPointer::word_size();
196 #endif
197 }
198 }
199
200 HeapWord* ShenandoahHeapRegion::object_iterate_careful(ObjectClosureCareful* blk) {
201 HeapWord * limit = concurrent_iteration_safe_limit();
202 assert(limit <= top(), "sanity check");
203 for (HeapWord* p = bottom() + BrooksPointer::word_size(); p < limit;) {
204 size_t size = blk->do_object_careful(oop(p));
205 if (size == 0) {
206 return p; // failed at p
207 } else {
208 p += size + BrooksPointer::word_size();
209 }
210 }
211 return NULL; // all done
212 }
213
214 void ShenandoahHeapRegion::fill_region() {
215 ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap();
216
217 if (free() > (BrooksPointer::word_size() + CollectedHeap::min_fill_size())) {
218 HeapWord* filler = allocate(BrooksPointer::word_size());
219 HeapWord* obj = allocate(end() - top());
220 sh->fill_with_object(obj, end() - obj);
221 BrooksPointer::initialize(oop(obj));
222 }
223 }
224
225 void ShenandoahHeapRegion::set_humongous_start(bool start) {
226 _humongous_start = start;
227 }
228
229 void ShenandoahHeapRegion::set_humongous_continuation(bool continuation) {
230 _humongous_continuation = continuation;
231 }
232
233 bool ShenandoahHeapRegion::is_humongous() const {
234 return _humongous_start || _humongous_continuation;
235 }
236
237 bool ShenandoahHeapRegion::is_humongous_start() const {
238 return _humongous_start;
239 }
240
241 bool ShenandoahHeapRegion::is_humongous_continuation() const {
242 return _humongous_continuation;
243 }
244
245 void ShenandoahHeapRegion::recycle() {
246 ContiguousSpace::initialize(reserved, true, false);
247 clear_live_data();
248 _humongous_start = false;
249 _humongous_continuation = false;
250 _recycled = true;
251 set_in_collection_set(false);
252 // Reset C-TAMS pointer to ensure size-based iteration, everything
253 // in that regions is going to be new objects.
254 _heap->set_complete_top_at_mark_start(bottom(), bottom());
255 // We can only safely reset the C-TAMS pointer if the bitmap is clear for that region.
256 assert(_heap->is_complete_bitmap_clear_range(bottom(), end()), "must be clear");
257 }
258
259 HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const {
260 assert(MemRegion(bottom(), end()).contains(p),
261 "p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
262 p2i(p), p2i(bottom()), p2i(end()));
263 if (p >= top()) {
264 return top();
265 } else {
266 HeapWord* last = bottom() + BrooksPointer::word_size();
267 HeapWord* cur = last;
268 while (cur <= p) {
269 last = cur;
270 cur += oop(cur)->size() + BrooksPointer::word_size();
271 }
272 assert(oop(last)->is_oop(),
273 PTR_FORMAT" should be an object start", p2i(last));
274 return last;
275 }
276 }
277
278 void ShenandoahHeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
279 // Absolute minimums we should not ever break:
280 static const size_t MIN_REGION_SIZE = 256*K;
281 static const size_t MIN_NUM_REGIONS = 10;
282
283 uintx region_size;
284 if (FLAG_IS_DEFAULT(ShenandoahHeapRegionSize)) {
285 if (ShenandoahMinRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
286 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
287 "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "K).",
288 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahMinRegionSize/K);
289 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
290 }
291 if (ShenandoahMinRegionSize < MIN_REGION_SIZE) {
292 err_msg message("" SIZE_FORMAT "K should not be lower than minimum region size (" SIZE_FORMAT "K).",
293 ShenandoahMinRegionSize/K, MIN_REGION_SIZE/K);
294 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
295 }
296 if (ShenandoahMinRegionSize < MinTLABSize) {
297 err_msg message("" SIZE_FORMAT "K should not be lower than TLAB size size (" SIZE_FORMAT "K).",
298 ShenandoahMinRegionSize/K, MinTLABSize/K);
299 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
300 }
301 if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) {
302 err_msg message("" SIZE_FORMAT "K should not be lower than min region size (" SIZE_FORMAT "K).",
303 ShenandoahMaxRegionSize/K, MIN_REGION_SIZE/K);
304 vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message);
305 }
306 if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) {
307 err_msg message("Minimum (" SIZE_FORMAT "K) should be larger than maximum (" SIZE_FORMAT "K).",
308 ShenandoahMinRegionSize/K, ShenandoahMaxRegionSize/K);
309 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message);
310 }
311 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
312 region_size = MAX2(average_heap_size / ShenandoahTargetNumRegions,
313 ShenandoahMinRegionSize);
314
315 // Now make sure that we don't go over or under our limits.
316 region_size = MAX2(ShenandoahMinRegionSize, region_size);
317 region_size = MIN2(ShenandoahMaxRegionSize, region_size);
318
319 } else {
320 if (ShenandoahHeapRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
321 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
322 "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "K).",
323 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahHeapRegionSize/K);
324 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
325 }
326 if (ShenandoahHeapRegionSize < MIN_REGION_SIZE) {
327 err_msg message("" SIZE_FORMAT " should not be lower than min region size (" SIZE_FORMAT "K).",
328 ShenandoahHeapRegionSize/K, MIN_REGION_SIZE/K);
329 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
330 }
331 region_size = ShenandoahHeapRegionSize;
332 }
333
334 // Make sure region size is at least one large page, if enabled.
335 // Otherwise, mem-protecting one region may falsely protect the adjacent
336 // regions too.
337 if (UseLargePages) {
338 region_size = MAX2(region_size, os::large_page_size());
339 }
340
341 int region_size_log = log2_long((jlong) region_size);
342 // Recalculate the region size to make sure it's a power of
343 // 2. This means that region_size is the largest power of 2 that's
344 // <= what we've calculated so far.
345 region_size = ((uintx)1 << region_size_log);
346
347 // Now, set up the globals.
348 guarantee(RegionSizeShift == 0, "we should only set it once");
349 RegionSizeShift = region_size_log;
350
351 guarantee(RegionSizeBytes == 0, "we should only set it once");
352 RegionSizeBytes = (size_t)region_size;
353
354 log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", RegionSizeBytes / M);
355 log_info(gc, init)("Region size in bytes: "SIZE_FORMAT, RegionSizeBytes);
356 log_info(gc, init)("Region size shift: "SIZE_FORMAT, RegionSizeShift);
357 log_info(gc, init)("Initial number of regions: "SIZE_FORMAT, initial_heap_size / RegionSizeBytes);
358 log_info(gc, init)("Maximum number of regions: "SIZE_FORMAT, max_heap_size / RegionSizeBytes);
359 }
360
361 CompactibleSpace* ShenandoahHeapRegion::next_compaction_space() const {
362 return _heap->next_compaction_region(this);
363 }
364
365 void ShenandoahHeapRegion::prepare_for_compaction(CompactPoint* cp) {
366 scan_and_forward(this, cp);
367 }
368
369 void ShenandoahHeapRegion::adjust_pointers() {
370 // Check first is there is any work to do.
371 if (used() == 0) {
372 return; // Nothing to do.
373 }
374
375 scan_and_adjust_pointers(this);
376 }
377
378 void ShenandoahHeapRegion::compact() {
379 assert(!is_humongous(), "Shouldn't be compacting humongous regions");
380 scan_and_compact(this);
381 }
382
383 void ShenandoahHeapRegion::pin() {
384 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
385 assert(_critical_pins >= 0, "sanity");
386 Atomic::inc(&_critical_pins);
387 }
388
389 void ShenandoahHeapRegion::unpin() {
390 assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
391 Atomic::dec(&_critical_pins);
392 assert(_critical_pins >= 0, "sanity");
393 }
394
395 bool ShenandoahHeapRegion::is_pinned() {
396 jint v = OrderAccess::load_acquire(&_critical_pins);
397 assert(v >= 0, "sanity");
398 return v > 0;
399 }