Tue, 16 Feb 2016 21:42:29 +0000
8072725: Provide more granular levels for GC verification
Summary: Add option VerifySubSet to selectively verify the memory sub-systems
Reviewed-by: kevinw, jmasa
1 /*
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25 #include "precompiled.hpp"
26 #include "gc_implementation/shared/collectorCounters.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/blockOffsetTable.inline.hpp"
29 #include "memory/generation.inline.hpp"
30 #include "memory/generationSpec.hpp"
31 #include "memory/space.hpp"
32 #include "memory/tenuredGeneration.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/java.hpp"
35 #include "utilities/macros.hpp"
36 #if INCLUDE_ALL_GCS
37 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
38 #endif
40 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
41 size_t initial_byte_size, int level,
42 GenRemSet* remset) :
43 OneContigSpaceCardGeneration(rs, initial_byte_size,
44 level, remset, NULL)
45 {
46 HeapWord* bottom = (HeapWord*) _virtual_space.low();
47 HeapWord* end = (HeapWord*) _virtual_space.high();
48 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
49 _the_space->reset_saved_mark();
50 _shrink_factor = 0;
51 _capacity_at_prologue = 0;
53 _gc_stats = new GCStats();
55 // initialize performance counters
57 const char* gen_name = "old";
59 // Generation Counters -- generation 1, 1 subspace
60 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space);
62 _gc_counters = new CollectorCounters("MSC", 1);
64 _space_counters = new CSpaceCounters(gen_name, 0,
65 _virtual_space.reserved_size(),
66 _the_space, _gen_counters);
67 #if INCLUDE_ALL_GCS
68 if (UseParNewGC) {
69 typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;
70 _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,
71 ParallelGCThreads, mtGC);
72 if (_alloc_buffers == NULL)
73 vm_exit_during_initialization("Could not allocate alloc_buffers");
74 for (uint i = 0; i < ParallelGCThreads; i++) {
75 _alloc_buffers[i] =
76 new ParGCAllocBufferWithBOT(OldPLABSize, _bts);
77 if (_alloc_buffers[i] == NULL)
78 vm_exit_during_initialization("Could not allocate alloc_buffers");
79 }
80 } else {
81 _alloc_buffers = NULL;
82 }
83 #endif // INCLUDE_ALL_GCS
84 }
87 const char* TenuredGeneration::name() const {
88 return "tenured generation";
89 }
91 void TenuredGeneration::gc_prologue(bool full) {
92 _capacity_at_prologue = capacity();
93 _used_at_prologue = used();
94 if (VerifyBeforeGC) {
95 verify_alloc_buffers_clean();
96 }
97 }
99 void TenuredGeneration::gc_epilogue(bool full) {
100 if (VerifyAfterGC) {
101 verify_alloc_buffers_clean();
102 }
103 OneContigSpaceCardGeneration::gc_epilogue(full);
104 }
107 bool TenuredGeneration::should_collect(bool full,
108 size_t size,
109 bool is_tlab) {
110 // This should be one big conditional or (||), but I want to be able to tell
111 // why it returns what it returns (without re-evaluating the conditionals
112 // in case they aren't idempotent), so I'm doing it this way.
113 // DeMorgan says it's okay.
114 bool result = false;
115 if (!result && full) {
116 result = true;
117 if (PrintGC && Verbose) {
118 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
119 " full");
120 }
121 }
122 if (!result && should_allocate(size, is_tlab)) {
123 result = true;
124 if (PrintGC && Verbose) {
125 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
126 " should_allocate(" SIZE_FORMAT ")",
127 size);
128 }
129 }
130 // If we don't have very much free space.
131 // XXX: 10000 should be a percentage of the capacity!!!
132 if (!result && free() < 10000) {
133 result = true;
134 if (PrintGC && Verbose) {
135 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
136 " free(): " SIZE_FORMAT,
137 free());
138 }
139 }
140 // If we had to expand to accomodate promotions from younger generations
141 if (!result && _capacity_at_prologue < capacity()) {
142 result = true;
143 if (PrintGC && Verbose) {
144 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
145 "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
146 _capacity_at_prologue, capacity());
147 }
148 }
149 return result;
150 }
152 void TenuredGeneration::collect(bool full,
153 bool clear_all_soft_refs,
154 size_t size,
155 bool is_tlab) {
156 retire_alloc_buffers_before_full_gc();
157 OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
158 size, is_tlab);
159 }
161 void TenuredGeneration::compute_new_size() {
162 assert_locked_or_safepoint(Heap_lock);
164 // Compute some numbers about the state of the heap.
165 const size_t used_after_gc = used();
166 const size_t capacity_after_gc = capacity();
168 CardGeneration::compute_new_size();
170 assert(used() == used_after_gc && used_after_gc <= capacity(),
171 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
172 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
173 }
174 void TenuredGeneration::update_gc_stats(int current_level,
175 bool full) {
176 // If the next lower level(s) has been collected, gather any statistics
177 // that are of interest at this point.
178 if (!full && (current_level + 1) == level()) {
179 // Calculate size of data promoted from the younger generations
180 // before doing the collection.
181 size_t used_before_gc = used();
183 // If the younger gen collections were skipped, then the
184 // number of promoted bytes will be 0 and adding it to the
185 // average will incorrectly lessen the average. It is, however,
186 // also possible that no promotion was needed.
187 if (used_before_gc >= _used_at_prologue) {
188 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
189 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
190 }
191 }
192 }
194 void TenuredGeneration::update_counters() {
195 if (UsePerfData) {
196 _space_counters->update_all();
197 _gen_counters->update_all();
198 }
199 }
202 #if INCLUDE_ALL_GCS
203 oop TenuredGeneration::par_promote(int thread_num,
204 oop old, markOop m, size_t word_sz) {
206 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
207 HeapWord* obj_ptr = buf->allocate(word_sz);
208 bool is_lab = true;
209 if (obj_ptr == NULL) {
210 #ifndef PRODUCT
211 if (Universe::heap()->promotion_should_fail()) {
212 return NULL;
213 }
214 #endif // #ifndef PRODUCT
216 // Slow path:
217 if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {
218 // Is small enough; abandon this buffer and start a new one.
219 size_t buf_size = buf->word_sz();
220 HeapWord* buf_space =
221 TenuredGeneration::par_allocate(buf_size, false);
222 if (buf_space == NULL) {
223 buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);
224 }
225 if (buf_space != NULL) {
226 buf->retire(false, false);
227 buf->set_buf(buf_space);
228 obj_ptr = buf->allocate(word_sz);
229 assert(obj_ptr != NULL, "Buffer was definitely big enough...");
230 }
231 };
232 // Otherwise, buffer allocation failed; try allocating object
233 // individually.
234 if (obj_ptr == NULL) {
235 obj_ptr = TenuredGeneration::par_allocate(word_sz, false);
236 if (obj_ptr == NULL) {
237 obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);
238 }
239 }
240 if (obj_ptr == NULL) return NULL;
241 }
242 assert(obj_ptr != NULL, "program logic");
243 Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);
244 oop obj = oop(obj_ptr);
245 // Restore the mark word copied above.
246 obj->set_mark(m);
247 return obj;
248 }
250 void TenuredGeneration::par_promote_alloc_undo(int thread_num,
251 HeapWord* obj,
252 size_t word_sz) {
253 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
254 if (buf->contains(obj)) {
255 guarantee(buf->contains(obj + word_sz - 1),
256 "should contain whole object");
257 buf->undo_allocation(obj, word_sz);
258 } else {
259 CollectedHeap::fill_with_object(obj, word_sz);
260 }
261 }
263 void TenuredGeneration::par_promote_alloc_done(int thread_num) {
264 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
265 buf->retire(true, ParallelGCRetainPLAB);
266 }
268 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {
269 if (UseParNewGC) {
270 for (uint i = 0; i < ParallelGCThreads; i++) {
271 _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);
272 }
273 }
274 }
276 // Verify that any retained parallel allocation buffers do not
277 // intersect with dirty cards.
278 void TenuredGeneration::verify_alloc_buffers_clean() {
279 if (UseParNewGC) {
280 for (uint i = 0; i < ParallelGCThreads; i++) {
281 _rs->verify_aligned_region_empty(_alloc_buffers[i]->range());
282 }
283 }
284 }
286 #else // INCLUDE_ALL_GCS
287 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}
288 void TenuredGeneration::verify_alloc_buffers_clean() {}
289 #endif // INCLUDE_ALL_GCS
291 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
292 size_t available = max_contiguous_available();
293 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average();
294 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes);
295 if (PrintGC && Verbose) {
296 gclog_or_tty->print_cr(
297 "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
298 "max_promo("SIZE_FORMAT")",
299 res? "":" not", available, res? ">=":"<",
300 av_promo, max_promotion_in_bytes);
301 }
302 return res;
303 }