1 /*
  2  * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "gc/parallel/objectStartArray.inline.hpp"
 27 #include "gc/parallel/parallelArguments.hpp"
 28 #include "gc/parallel/parallelScavengeHeap.hpp"
 29 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
 30 #include "gc/parallel/psCardTable.hpp"
 31 #include "gc/parallel/psOldGen.hpp"
 32 #include "gc/shared/cardTableBarrierSet.hpp"
 33 #include "gc/shared/gcLocker.hpp"
 34 #include "gc/shared/spaceDecorator.inline.hpp"
 35 #include "logging/log.hpp"
 36 #include "oops/oop.inline.hpp"
 37 #include "runtime/java.hpp"
 38 #include "utilities/align.hpp"
 39 
 40 PSOldGen::PSOldGen(ReservedSpace rs, size_t initial_size, size_t min_size,
 41                    size_t max_size, const char* perf_data_name, int level):
 42   _min_gen_size(min_size),
 43   _max_gen_size(max_size)
 44 {
 45   initialize(rs, initial_size, GenAlignment, perf_data_name, level);
 46 }
 47 
 48 void PSOldGen::initialize(ReservedSpace rs, size_t initial_size, size_t alignment,
 49                           const char* perf_data_name, int level) {
 50   initialize_virtual_space(rs, initial_size, alignment);
 51   initialize_work(perf_data_name, level);
 52 
 53   // The old gen can grow to max_gen_size().  _reserve reflects only
 54   // the current maximum that can be committed.
 55   assert(_reserved.byte_size() <= max_gen_size(), "Consistency check");
 56 
 57   initialize_performance_counters(perf_data_name, level);
 58 }
 59 
 60 void PSOldGen::initialize_virtual_space(ReservedSpace rs,
 61                                         size_t initial_size,
 62                                         size_t alignment) {
 63 
 64   _virtual_space = new PSVirtualSpace(rs, alignment);
 65   if (!_virtual_space->expand_by(initial_size)) {
 66     vm_exit_during_initialization("Could not reserve enough space for "
 67                                   "object heap");
 68   }
 69 }
 70 
 71 void PSOldGen::initialize_work(const char* perf_data_name, int level) {
 72   //
 73   // Basic memory initialization
 74   //
 75 
 76   MemRegion limit_reserved((HeapWord*)virtual_space()->low_boundary(),
 77                            heap_word_size(max_gen_size()));
 78   assert(limit_reserved.byte_size() == max_gen_size(),
 79     "word vs bytes confusion");
 80   //
 81   // Object start stuff
 82   //
 83 
 84   start_array()->initialize(limit_reserved);
 85 
 86   _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
 87                         (HeapWord*)virtual_space()->high_boundary());
 88 
 89   //
 90   // Card table stuff
 91   //
 92 
 93   MemRegion cmr((HeapWord*)virtual_space()->low(),
 94                 (HeapWord*)virtual_space()->high());
 95   if (ZapUnusedHeapArea) {
 96     // Mangle newly committed space immediately rather than
 97     // waiting for the initialization of the space even though
 98     // mangling is related to spaces.  Doing it here eliminates
 99     // the need to carry along information that a complete mangling
100     // (bottom to end) needs to be done.
101     SpaceMangler::mangle_region(cmr);
102   }
103 
104   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
105   PSCardTable* ct = heap->card_table();
106   ct->resize_covered_region(cmr);
107 
108   // Verify that the start and end of this generation is the start of a card.
109   // If this wasn't true, a single card could span more than one generation,
110   // which would cause problems when we commit/uncommit memory, and when we
111   // clear and dirty cards.
112   guarantee(ct->is_card_aligned(_reserved.start()), "generation must be card aligned");
113   if (_reserved.end() != heap->reserved_region().end()) {
114     // Don't check at the very end of the heap as we'll assert that we're probing off
115     // the end if we try.
116     guarantee(ct->is_card_aligned(_reserved.end()), "generation must be card aligned");
117   }
118 
119   //
120   // ObjectSpace stuff
121   //
122 
123   _object_space = new MutableSpace(virtual_space()->alignment());
124   object_space()->initialize(cmr,
125                              SpaceDecorator::Clear,
126                              SpaceDecorator::Mangle,
127                              MutableSpace::SetupPages,
128                              &ParallelScavengeHeap::heap()->workers());
129 
130   // Update the start_array
131   start_array()->set_covered_region(cmr);
132 }
133 
134 void PSOldGen::initialize_performance_counters(const char* perf_data_name, int level) {
135   // Generation Counters, generation 'level', 1 subspace
136   _gen_counters = new PSGenerationCounters(perf_data_name, level, 1, min_gen_size(),
137                                            max_gen_size(), virtual_space());
138   _space_counters = new SpaceCounters(perf_data_name, 0,
139                                       virtual_space()->reserved_size(),
140                                       _object_space, _gen_counters);
141 }
142 
143 // Assume that the generation has been allocated if its
144 // reserved size is not 0.
145 bool  PSOldGen::is_allocated() {
146   return virtual_space()->reserved_size() != 0;
147 }
148 
149 size_t PSOldGen::num_iterable_blocks() const {
150   return (object_space()->used_in_bytes() + IterateBlockSize - 1) / IterateBlockSize;
151 }
152 
153 void PSOldGen::object_iterate_block(ObjectClosure* cl, size_t block_index) {
154   size_t block_word_size = IterateBlockSize / HeapWordSize;
155   assert((block_word_size % (ObjectStartArray::block_size)) == 0,
156          "Block size not a multiple of start_array block");
157 
158   MutableSpace *space = object_space();
159 
160   HeapWord* begin = space->bottom() + block_index * block_word_size;
161   HeapWord* end = MIN2(space->top(), begin + block_word_size);
162 
163   if (!start_array()->object_starts_in_range(begin, end)) {
164     return;
165   }
166 
167   // Get object starting at or reaching into this block.
168   HeapWord* start = start_array()->object_start(begin);
169   if (start < begin) {
170     start += cast_to_oop(start)->size();
171   }
172   assert(start >= begin,
173          "Object address" PTR_FORMAT " must be larger or equal to block address at " PTR_FORMAT,
174          p2i(start), p2i(begin));
175   // Iterate all objects until the end.
176   for (HeapWord* p = start; p < end; p += cast_to_oop(p)->size()) {
177     cl->do_object(cast_to_oop(p));
178   }
179 }
180 
181 bool PSOldGen::expand_for_allocate(size_t word_size) {
182   assert(word_size > 0, "allocating zero words?");
183   bool result = true;
184   {
185     MutexLocker x(ExpandHeap_lock);
186     // Avoid "expand storms" by rechecking available space after obtaining
187     // the lock, because another thread may have already made sufficient
188     // space available.  If insufficient space available, that will remain
189     // true until we expand, since we have the lock.  Other threads may take
190     // the space we need before we can allocate it, regardless of whether we
191     // expand.  That's okay, we'll just try expanding again.
192     if (object_space()->needs_expand(word_size)) {
193       result = expand(word_size*HeapWordSize);
194     }
195   }
196   if (GCExpandToAllocateDelayMillis > 0) {
197     os::naked_sleep(GCExpandToAllocateDelayMillis);
198   }
199   return result;
200 }
201 
202 bool PSOldGen::expand(size_t bytes) {
203   assert_lock_strong(ExpandHeap_lock);
204   assert_locked_or_safepoint(Heap_lock);
205   assert(bytes > 0, "precondition");
206   const size_t alignment = virtual_space()->alignment();
207   size_t aligned_bytes  = align_up(bytes, alignment);
208   size_t aligned_expand_bytes = align_up(MinHeapDeltaBytes, alignment);
209 
210   if (UseNUMA) {
211     // With NUMA we use round-robin page allocation for the old gen. Expand by at least
212     // providing a page per lgroup. Alignment is larger or equal to the page size.
213     aligned_expand_bytes = MAX2(aligned_expand_bytes, alignment * os::numa_get_groups_num());
214   }
215   if (aligned_bytes == 0) {
216     // The alignment caused the number of bytes to wrap.  A call to expand
217     // implies a best effort to expand by "bytes" but not a guarantee.  Align
218     // down to give a best effort.  This is likely the most that the generation
219     // can expand since it has some capacity to start with.
220     aligned_bytes = align_down(bytes, alignment);
221   }
222 
223   bool success = false;
224   if (aligned_expand_bytes > aligned_bytes) {
225     success = expand_by(aligned_expand_bytes);
226   }
227   if (!success) {
228     success = expand_by(aligned_bytes);
229   }
230   if (!success) {
231     success = expand_to_reserved();
232   }
233 
234   if (success && GCLocker::is_active_and_needs_gc()) {
235     log_debug(gc)("Garbage collection disabled, expanded heap instead");
236   }
237   return success;
238 }
239 
240 bool PSOldGen::expand_by(size_t bytes) {
241   assert_lock_strong(ExpandHeap_lock);
242   assert_locked_or_safepoint(Heap_lock);
243   assert(bytes > 0, "precondition");
244   bool result = virtual_space()->expand_by(bytes);
245   if (result) {
246     if (ZapUnusedHeapArea) {
247       // We need to mangle the newly expanded area. The memregion spans
248       // end -> new_end, we assume that top -> end is already mangled.
249       // Do the mangling before post_resize() is called because
250       // the space is available for allocation after post_resize();
251       HeapWord* const virtual_space_high = (HeapWord*) virtual_space()->high();
252       assert(object_space()->end() < virtual_space_high,
253         "Should be true before post_resize()");
254       MemRegion mangle_region(object_space()->end(), virtual_space_high);
255       // Note that the object space has not yet been updated to
256       // coincide with the new underlying virtual space.
257       SpaceMangler::mangle_region(mangle_region);
258     }
259     post_resize();
260     if (UsePerfData) {
261       _space_counters->update_capacity();
262       _gen_counters->update_all();
263     }
264   }
265 
266   if (result) {
267     size_t new_mem_size = virtual_space()->committed_size();
268     size_t old_mem_size = new_mem_size - bytes;
269     log_debug(gc)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
270                   name(), old_mem_size/K, bytes/K, new_mem_size/K);
271   }
272 
273   return result;
274 }
275 
276 bool PSOldGen::expand_to_reserved() {
277   assert_lock_strong(ExpandHeap_lock);
278   assert_locked_or_safepoint(Heap_lock);
279 
280   bool result = false;
281   const size_t remaining_bytes = virtual_space()->uncommitted_size();
282   if (remaining_bytes > 0) {
283     result = expand_by(remaining_bytes);
284     DEBUG_ONLY(if (!result) log_warning(gc)("grow to reserve failed"));
285   }
286   return result;
287 }
288 
289 void PSOldGen::shrink(size_t bytes) {
290   assert_lock_strong(ExpandHeap_lock);
291   assert_locked_or_safepoint(Heap_lock);
292 
293   size_t size = align_down(bytes, virtual_space()->alignment());
294   if (size > 0) {
295     assert_lock_strong(ExpandHeap_lock);
296     virtual_space()->shrink_by(bytes);
297     post_resize();
298 
299     size_t new_mem_size = virtual_space()->committed_size();
300     size_t old_mem_size = new_mem_size + bytes;
301     log_debug(gc)("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
302                   name(), old_mem_size/K, bytes/K, new_mem_size/K);
303   }
304 }
305 
306 void PSOldGen::resize(size_t desired_free_space) {
307   const size_t alignment = virtual_space()->alignment();
308   const size_t size_before = virtual_space()->committed_size();
309   size_t new_size = used_in_bytes() + desired_free_space;
310   if (new_size < used_in_bytes()) {
311     // Overflowed the addition.
312     new_size = max_gen_size();
313   }
314   // Adjust according to our min and max
315   new_size = clamp(new_size, min_gen_size(), max_gen_size());
316 
317   assert(max_gen_size() >= reserved().byte_size(), "max new size problem?");
318   new_size = align_up(new_size, alignment);
319 
320   const size_t current_size = capacity_in_bytes();
321 
322   log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: "
323     "desired free: " SIZE_FORMAT " used: " SIZE_FORMAT
324     " new size: " SIZE_FORMAT " current size " SIZE_FORMAT
325     " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
326     desired_free_space, used_in_bytes(), new_size, current_size,
327     max_gen_size(), min_gen_size());
328 
329   if (new_size == current_size) {
330     // No change requested
331     return;
332   }
333   if (new_size > current_size) {
334     size_t change_bytes = new_size - current_size;
335     MutexLocker x(ExpandHeap_lock);
336     expand(change_bytes);
337   } else {
338     size_t change_bytes = current_size - new_size;
339     MutexLocker x(ExpandHeap_lock);
340     shrink(change_bytes);
341   }
342 
343   log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: collection: %d (" SIZE_FORMAT ") -> (" SIZE_FORMAT ") ",
344                       ParallelScavengeHeap::heap()->total_collections(),
345                       size_before,
346                       virtual_space()->committed_size());
347 }
348 
349 // NOTE! We need to be careful about resizing. During a GC, multiple
350 // allocators may be active during heap expansion. If we allow the
351 // heap resizing to become visible before we have correctly resized
352 // all heap related data structures, we may cause program failures.
353 void PSOldGen::post_resize() {
354   // First construct a memregion representing the new size
355   MemRegion new_memregion((HeapWord*)virtual_space()->low(),
356     (HeapWord*)virtual_space()->high());
357   size_t new_word_size = new_memregion.word_size();
358 
359   start_array()->set_covered_region(new_memregion);
360   ParallelScavengeHeap::heap()->card_table()->resize_covered_region(new_memregion);
361 
362   WorkGang* workers = Thread::current()->is_VM_thread() ?
363                       &ParallelScavengeHeap::heap()->workers() : NULL;
364 
365   // The update of the space's end is done by this call.  As that
366   // makes the new space available for concurrent allocation, this
367   // must be the last step when expanding.
368   object_space()->initialize(new_memregion,
369                              SpaceDecorator::DontClear,
370                              SpaceDecorator::DontMangle,
371                              MutableSpace::SetupPages,
372                              workers);
373 
374   assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()),
375     "Sanity");
376 }
377 
378 void PSOldGen::print() const { print_on(tty);}
379 void PSOldGen::print_on(outputStream* st) const {
380   st->print(" %-15s", name());
381   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
382               capacity_in_bytes()/K, used_in_bytes()/K);
383   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
384                 p2i(virtual_space()->low_boundary()),
385                 p2i(virtual_space()->high()),
386                 p2i(virtual_space()->high_boundary()));
387 
388   st->print("  object"); object_space()->print_on(st);
389 }
390 
391 void PSOldGen::update_counters() {
392   if (UsePerfData) {
393     _space_counters->update_all();
394     _gen_counters->update_all();
395   }
396 }
397 
398 void PSOldGen::verify() {
399   object_space()->verify();
400 }
401 
402 class VerifyObjectStartArrayClosure : public ObjectClosure {
403   PSOldGen* _old_gen;
404   ObjectStartArray* _start_array;
405 
406  public:
407   VerifyObjectStartArrayClosure(PSOldGen* old_gen, ObjectStartArray* start_array) :
408     _old_gen(old_gen), _start_array(start_array) { }
409 
410   virtual void do_object(oop obj) {
411     HeapWord* test_addr = cast_from_oop<HeapWord*>(obj) + 1;
412     guarantee(_start_array->object_start(test_addr) == cast_from_oop<HeapWord*>(obj), "ObjectStartArray cannot find start of object");
413     guarantee(_start_array->is_block_allocated(cast_from_oop<HeapWord*>(obj)), "ObjectStartArray missing block allocation");
414   }
415 };
416 
417 void PSOldGen::verify_object_start_array() {
418   VerifyObjectStartArrayClosure check( this, &_start_array );
419   object_iterate(&check);
420 }
421 
422 #ifndef PRODUCT
423 void PSOldGen::record_spaces_top() {
424   assert(ZapUnusedHeapArea, "Not mangling unused space");
425   object_space()->set_top_for_allocations();
426 }
427 #endif