1 /*
2 * Copyright (c) 2017, 2019, Red Hat, Inc. All rights reserved.
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 "precompiled.hpp"
25 #include "code/codeCache.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
28 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "memory/universe.hpp"
31
32 ShenandoahParallelCodeCacheIterator::ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps) {
33 _length = heaps->length();
34 _iters = NEW_C_HEAP_ARRAY(ShenandoahParallelCodeHeapIterator, _length, mtGC);
35 for (int h = 0; h < _length; h++) {
36 _iters[h] = ShenandoahParallelCodeHeapIterator(heaps->at(h));
37 }
38 }
39
40 ShenandoahParallelCodeCacheIterator::~ShenandoahParallelCodeCacheIterator() {
41 FREE_C_HEAP_ARRAY(ParallelCodeHeapIterator, _iters);
42 }
43
44 void ShenandoahParallelCodeCacheIterator::parallel_blobs_do(CodeBlobClosure* f) {
45 for (int c = 0; c < _length; c++) {
46 _iters[c].parallel_blobs_do(f);
47 }
48 }
49
50 ShenandoahParallelCodeHeapIterator::ShenandoahParallelCodeHeapIterator(CodeHeap* heap) :
51 _heap(heap), _claimed_idx(0), _finished(false) {
52 }
53
54 void ShenandoahParallelCodeHeapIterator::parallel_blobs_do(CodeBlobClosure* f) {
55 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
56
57 /*
58 * Parallel code heap walk.
59 *
60 * This code makes all threads scan all code heaps, but only one thread would execute the
61 * closure on given blob. This is achieved by recording the "claimed" blocks: if a thread
62 * had claimed the block, it can process all blobs in it. Others have to fast-forward to
63 * next attempt without processing.
64 *
65 * Late threads would return immediately if iterator is finished.
66 */
67
68 if (_finished) {
69 return;
70 }
71
72 int stride = 256; // educated guess
73 int stride_mask = stride - 1;
74 assert (is_power_of_2(stride), "sanity");
75
76 int count = 0;
77 bool process_block = true;
78
79 for (CodeBlob *cb = CodeCache::first_blob(_heap); cb != NULL; cb = CodeCache::next_blob(_heap, cb)) {
80 int current = count++;
81 if ((current & stride_mask) == 0) {
82 process_block = (current >= _claimed_idx) &&
83 (Atomic::cmpxchg(current + stride, &_claimed_idx, current) == current);
84 }
85 if (process_block) {
86 if (cb->is_alive()) {
87 f->do_code_blob(cb);
88 #ifdef ASSERT
89 if (cb->is_nmethod())
90 Universe::heap()->verify_nmethod((nmethod*)cb);
91 #endif
92 }
93 }
94 }
95
96 _finished = true;
97 }
98
99 class ShenandoahNMethodOopDetector : public OopClosure {
100 private:
101 ResourceMark rm; // For growable array allocation below.
102 GrowableArray<oop*> _oops;
103
104 public:
105 ShenandoahNMethodOopDetector() : _oops(10) {};
106
107 void do_oop(oop* o) {
108 _oops.append(o);
109 }
110 void do_oop(narrowOop* o) {
111 fatal("NMethods should not have compressed oops embedded.");
112 }
113
114 GrowableArray<oop*>* oops() {
115 return &_oops;
116 }
117
118 bool has_oops() {
119 return !_oops.is_empty();
120 }
121 };
122
123 GrowableArray<ShenandoahNMethod*>* ShenandoahCodeRoots::_recorded_nms;
124
125 void ShenandoahCodeRoots::initialize() {
126 _recorded_nms = new (ResourceObj::C_HEAP, mtGC) GrowableArray<ShenandoahNMethod*>(100, true, mtGC);
127 }
128
129 void ShenandoahCodeRoots::add_nmethod(nmethod* nm) {
130 assert(CodeCache_lock->owned_by_self(), "Must own CodeCache_lock");
131 switch (ShenandoahCodeRootsStyle) {
132 case 0:
133 case 1:
134 break;
135 case 2: {
136 ShenandoahNMethodOopDetector detector;
137 nm->oops_do(&detector);
138
139 if (detector.has_oops()) {
140 ShenandoahNMethod* nmr = new ShenandoahNMethod(nm, detector.oops());
141 nmr->assert_alive_and_correct();
142 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
143 if (idx != -1) {
144 ShenandoahNMethod* old = _recorded_nms->at(idx);
145 _recorded_nms->at_put(idx, nmr);
146 delete old;
147 } else {
148 _recorded_nms->append(nmr);
149 }
150 }
151 break;
152 }
153 default:
154 ShouldNotReachHere();
155 }
156 };
157
158 void ShenandoahCodeRoots::remove_nmethod(nmethod* nm) {
159 assert(CodeCache_lock->owned_by_self(), "Must own CodeCache_lock");
160 switch (ShenandoahCodeRootsStyle) {
161 case 0:
162 case 1: {
163 break;
164 }
165 case 2: {
166 ShenandoahNMethodOopDetector detector;
167 nm->oops_do(&detector, /* allow_zombie = */ true);
168
169 if (detector.has_oops()) {
170 int idx = _recorded_nms->find(nm, ShenandoahNMethod::find_with_nmethod);
171 assert(idx != -1, "nmethod " PTR_FORMAT " should be registered", p2i(nm));
172 ShenandoahNMethod* old = _recorded_nms->at(idx);
173 old->assert_same_oops(detector.oops());
174 _recorded_nms->delete_at(idx);
175 delete old;
176 }
177 break;
178 }
179 default:
180 ShouldNotReachHere();
181 }
182 }
183
184 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
185 _heap(ShenandoahHeap::heap()),
186 _par_iterator(CodeCache::heaps()),
187 _claimed(0) {
188 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
189 assert(!Thread::current()->is_Worker_thread(), "Should not be acquired by workers");
190 switch (ShenandoahCodeRootsStyle) {
191 case 0:
192 case 1: {
193 // No need to do anything here
194 break;
195 }
196 case 2: {
197 CodeCache_lock->lock();
198 break;
199 }
200 default:
201 ShouldNotReachHere();
202 }
203 }
204
205 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
206 switch (ShenandoahCodeRootsStyle) {
207 case 0:
208 case 1: {
209 // No need to do anything here
210 break;
211 }
212 case 2: {
213 CodeCache_lock->unlock();
214 break;
215 }
216 default:
217 ShouldNotReachHere();
218 }
219 }
220
221 template<bool CSET_FILTER>
222 void ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do(CodeBlobClosure *f) {
223 switch (ShenandoahCodeRootsStyle) {
224 case 0: {
225 if (_seq_claimed.try_set()) {
226 CodeCache::blobs_do(f);
227 }
228 break;
229 }
230 case 1: {
231 _par_iterator.parallel_blobs_do(f);
232 break;
233 }
234 case 2: {
235 ShenandoahCodeRootsIterator::fast_parallel_blobs_do<CSET_FILTER>(f);
236 break;
237 }
238 default:
239 ShouldNotReachHere();
240 }
241 }
242
243 void ShenandoahAllCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
244 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<false>(f);
245 }
246
247 void ShenandoahCsetCodeRootsIterator::possibly_parallel_blobs_do(CodeBlobClosure *f) {
248 ShenandoahCodeRootsIterator::dispatch_parallel_blobs_do<true>(f);
249 }
250
251 template <bool CSET_FILTER>
252 void ShenandoahCodeRootsIterator::fast_parallel_blobs_do(CodeBlobClosure *f) {
253 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
254
255 size_t stride = 256; // educated guess
256
257 GrowableArray<ShenandoahNMethod*>* list = ShenandoahCodeRoots::_recorded_nms;
258
259 size_t max = (size_t)list->length();
260 while (_claimed < max) {
261 size_t cur = Atomic::add(stride, &_claimed) - stride;
262 size_t start = cur;
263 size_t end = MIN2(cur + stride, max);
264 if (start >= max) break;
265
266 for (size_t idx = start; idx < end; idx++) {
267 ShenandoahNMethod* nmr = list->at((int) idx);
268 nmr->assert_alive_and_correct();
269
270 if (CSET_FILTER && !nmr->has_cset_oops(_heap)) {
271 continue;
272 }
273
274 f->do_code_blob(nmr->nm());
275 }
276 }
277 }
278
279 ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>* oops) {
280 _nm = nm;
281 _oops = NEW_C_HEAP_ARRAY(oop*, oops->length(), mtGC);
282 _oops_count = oops->length();
283 for (int c = 0; c < _oops_count; c++) {
284 _oops[c] = oops->at(c);
285 }
286 }
287
288 ShenandoahNMethod::~ShenandoahNMethod() {
289 if (_oops != NULL) {
290 FREE_C_HEAP_ARRAY(oop*, _oops);
291 }
292 }
293
294 bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {
295 for (int c = 0; c < _oops_count; c++) {
296 oop o = RawAccess<>::oop_load(_oops[c]);
297 if (heap->in_collection_set(o)) {
298 return true;
299 }
300 }
301 return false;
302 }
303
304 #ifdef ASSERT
305 void ShenandoahNMethod::assert_alive_and_correct() {
306 assert(_nm->is_alive(), "only alive nmethods here");
307 assert(_oops_count > 0, "should have filtered nmethods without oops before");
308 ShenandoahHeap* heap = ShenandoahHeap::heap();
309 for (int c = 0; c < _oops_count; c++) {
310 oop *loc = _oops[c];
311 assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
312 oop o = RawAccess<>::oop_load(loc);
313 shenandoah_assert_correct_except(loc, o, o == NULL || heap->is_full_gc_move_in_progress());
314 }
315 }
316
317 void ShenandoahNMethod::assert_same_oops(GrowableArray<oop*>* oops) {
318 assert(_oops_count == oops->length(), "should have the same number of oop*");
319 for (int c = 0; c < _oops_count; c++) {
320 assert(_oops[c] == oops->at(c), "should be the same oop*");
321 }
322 }
323 #endif