1 /*
2 * Copyright (c) 2003, 2010, 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_implementation/parallelScavenge/asPSYoungGen.hpp"
27 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
28 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
29 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
30 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
31 #include "gc_implementation/shared/gcUtil.hpp"
32 #include "gc_implementation/shared/spaceDecorator.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/java.hpp"
35
36 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
37 size_t minimum_byte_size,
38 size_t byte_size_limit) :
39 PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
40 _gen_size_limit(byte_size_limit) {
41 }
42
43
44 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
45 size_t init_byte_size,
46 size_t minimum_byte_size,
47 size_t byte_size_limit) :
48 //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
49 PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
50 _gen_size_limit(byte_size_limit) {
51
52 assert(vs->committed_size() == init_byte_size, "Cannot replace with");
53
54 _virtual_space = vs;
55 }
56
57 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
58 size_t alignment) {
59 assert(_init_gen_size != 0, "Should have a finite size");
60 _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
61 if (!_virtual_space->expand_by(_init_gen_size)) {
62 vm_exit_during_initialization("Could not reserve enough space for "
63 "object heap");
64 }
65 }
66
67 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
68 initialize_virtual_space(rs, alignment);
69 initialize_work();
70 }
71
72 size_t ASPSYoungGen::available_for_expansion() {
73
74 size_t current_committed_size = virtual_space()->committed_size();
75 assert((gen_size_limit() >= current_committed_size),
76 "generation size limit is wrong");
77 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
78 size_t result = gen_size_limit() - current_committed_size;
79 size_t result_aligned = align_size_down(result, heap->young_gen_alignment());
80 return result_aligned;
81 }
82
83 // Return the number of bytes the young gen is willing give up.
84 //
85 // Future implementations could check the survivors and if to_space is in the
86 // right place (below from_space), take a chunk from to_space.
87 size_t ASPSYoungGen::available_for_contraction() {
88
89 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
90 if (uncommitted_bytes != 0) {
91 return uncommitted_bytes;
92 }
93
94 if (eden_space()->is_empty()) {
95 // Respect the minimum size for eden and for the young gen as a whole.
96 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
97 const size_t eden_alignment = heap->intra_heap_alignment();
98 const size_t gen_alignment = heap->young_gen_alignment();
99
100 assert(eden_space()->capacity_in_bytes() >= eden_alignment,
101 "Alignment is wrong");
102 size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
103 eden_avail = align_size_down(eden_avail, gen_alignment);
104
105 assert(virtual_space()->committed_size() >= min_gen_size(),
106 "minimum gen size is wrong");
107 size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
108 assert(virtual_space()->is_aligned(gen_avail), "not aligned");
109
110 const size_t max_contraction = MIN2(eden_avail, gen_avail);
111 // See comment for ASPSOldGen::available_for_contraction()
112 // for reasons the "increment" fraction is used.
113 PSAdaptiveSizePolicy* policy = heap->size_policy();
114 size_t result = policy->eden_increment_aligned_down(max_contraction);
115 size_t result_aligned = align_size_down(result, gen_alignment);
116 if (PrintAdaptiveSizePolicy && Verbose) {
117 gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",
118 result_aligned/K);
119 gclog_or_tty->print_cr(" max_contraction %d K", max_contraction/K);
120 gclog_or_tty->print_cr(" eden_avail %d K", eden_avail/K);
121 gclog_or_tty->print_cr(" gen_avail %d K", gen_avail/K);
122 }
123 return result_aligned;
124
125 }
126
127 return 0;
128 }
129
130 // The current implementation only considers to the end of eden.
131 // If to_space is below from_space, to_space is not considered.
132 // to_space can be.
133 size_t ASPSYoungGen::available_to_live() {
134 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
135 const size_t alignment = heap->intra_heap_alignment();
136
137 // Include any space that is committed but is not in eden.
138 size_t available = pointer_delta(eden_space()->bottom(),
139 virtual_space()->low(),
140 sizeof(char));
141
142 const size_t eden_capacity = eden_space()->capacity_in_bytes();
143 if (eden_space()->is_empty() && eden_capacity > alignment) {
144 available += eden_capacity - alignment;
145 }
146 return available;
147 }
148
149 // Similar to PSYoungGen::resize_generation() but
150 // allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
151 // expands at the low end of the virtual space
152 // moves the boundary between the generations in order to expand
153 // some additional diagnostics
154 // If no additional changes are required, this can be deleted
155 // and the changes factored back into PSYoungGen::resize_generation().
156 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
157 const size_t alignment = virtual_space()->alignment();
158 size_t orig_size = virtual_space()->committed_size();
159 bool size_changed = false;
160
161 // There used to be a guarantee here that
162 // (eden_size + 2*survivor_size) <= _max_gen_size
163 // This requirement is enforced by the calculation of desired_size
164 // below. It may not be true on entry since the size of the
165 // eden_size is no bounded by the generation size.
166
167 assert(max_size() == reserved().byte_size(), "max gen size problem?");
168 assert(min_gen_size() <= orig_size && orig_size <= max_size(),
169 "just checking");
170
171 // Adjust new generation size
172 const size_t eden_plus_survivors =
173 align_size_up(eden_size + 2 * survivor_size, alignment);
174 size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
175 min_gen_size());
176 assert(desired_size <= gen_size_limit(), "just checking");
177
178 if (desired_size > orig_size) {
179 // Grow the generation
180 size_t change = desired_size - orig_size;
181 HeapWord* prev_low = (HeapWord*) virtual_space()->low();
182 if (!virtual_space()->expand_by(change)) {
183 return false;
184 }
185 if (ZapUnusedHeapArea) {
186 // Mangle newly committed space immediately because it
187 // can be done here more simply that after the new
188 // spaces have been computed.
189 HeapWord* new_low = (HeapWord*) virtual_space()->low();
190 assert(new_low < prev_low, "Did not grow");
191
192 MemRegion mangle_region(new_low, prev_low);
193 SpaceMangler::mangle_region(mangle_region);
194 }
195 size_changed = true;
196 } else if (desired_size < orig_size) {
197 size_t desired_change = orig_size - desired_size;
198
199 // How much is available for shrinking.
200 size_t available_bytes = limit_gen_shrink(desired_change);
201 size_t change = MIN2(desired_change, available_bytes);
202 virtual_space()->shrink_by(change);
203 size_changed = true;
204 } else {
205 if (Verbose && PrintGC) {
206 if (orig_size == gen_size_limit()) {
207 gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
208 SIZE_FORMAT "K", orig_size/K);
209 } else if (orig_size == min_gen_size()) {
210 gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
211 SIZE_FORMAT "K", orig_size/K);
212 }
213 }
214 }
215
216 if (size_changed) {
217 reset_after_change();
218 if (Verbose && PrintGC) {
219 size_t current_size = virtual_space()->committed_size();
220 gclog_or_tty->print_cr("ASPSYoung generation size changed: "
221 SIZE_FORMAT "K->" SIZE_FORMAT "K",
222 orig_size/K, current_size/K);
223 }
224 }
225
226 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
227 virtual_space()->committed_size() == max_size(), "Sanity");
228
229 return true;
230 }
231
232 // Similar to PSYoungGen::resize_spaces() but
233 // eden always starts at the low end of the committed virtual space
234 // current implementation does not allow holes between the spaces
235 // _young_generation_boundary has to be reset because it changes.
236 // so additional verification
237
238 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
239 size_t requested_survivor_size) {
240 assert(UseAdaptiveSizePolicy, "sanity check");
241 assert(requested_eden_size > 0 && requested_survivor_size > 0,
242 "just checking");
243
244 space_invariants();
245
246 // We require eden and to space to be empty
247 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
248 return;
249 }
250
251 if (PrintAdaptiveSizePolicy && Verbose) {
252 gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
253 SIZE_FORMAT
254 ", requested_survivor_size: " SIZE_FORMAT ")",
255 requested_eden_size, requested_survivor_size);
256 gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
257 SIZE_FORMAT,
258 eden_space()->bottom(),
259 eden_space()->end(),
260 pointer_delta(eden_space()->end(),
261 eden_space()->bottom(),
262 sizeof(char)));
263 gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
264 SIZE_FORMAT,
265 from_space()->bottom(),
266 from_space()->end(),
267 pointer_delta(from_space()->end(),
268 from_space()->bottom(),
269 sizeof(char)));
270 gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
271 SIZE_FORMAT,
272 to_space()->bottom(),
273 to_space()->end(),
274 pointer_delta( to_space()->end(),
275 to_space()->bottom(),
276 sizeof(char)));
277 }
278
279 // There's nothing to do if the new sizes are the same as the current
280 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
281 requested_survivor_size == from_space()->capacity_in_bytes() &&
282 requested_eden_size == eden_space()->capacity_in_bytes()) {
283 if (PrintAdaptiveSizePolicy && Verbose) {
284 gclog_or_tty->print_cr(" capacities are the right sizes, returning");
285 }
286 return;
287 }
288
289 char* eden_start = (char*)virtual_space()->low();
290 char* eden_end = (char*)eden_space()->end();
291 char* from_start = (char*)from_space()->bottom();
292 char* from_end = (char*)from_space()->end();
293 char* to_start = (char*)to_space()->bottom();
294 char* to_end = (char*)to_space()->end();
295
296 assert(eden_start < from_start, "Cannot push into from_space");
297
298 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
299 const size_t alignment = heap->intra_heap_alignment();
300 const bool maintain_minimum =
301 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
302
303 bool eden_from_to_order = from_start < to_start;
304 // Check whether from space is below to space
305 if (eden_from_to_order) {
306 // Eden, from, to
307
308 if (PrintAdaptiveSizePolicy && Verbose) {
309 gclog_or_tty->print_cr(" Eden, from, to:");
310 }
311
312 // Set eden
313 // "requested_eden_size" is a goal for the size of eden
314 // and may not be attainable. "eden_size" below is
315 // calculated based on the location of from-space and
316 // the goal for the size of eden. from-space is
317 // fixed in place because it contains live data.
318 // The calculation is done this way to avoid 32bit
319 // overflow (i.e., eden_start + requested_eden_size
320 // may too large for representation in 32bits).
321 size_t eden_size;
322 if (maintain_minimum) {
323 // Only make eden larger than the requested size if
324 // the minimum size of the generation has to be maintained.
325 // This could be done in general but policy at a higher
326 // level is determining a requested size for eden and that
327 // should be honored unless there is a fundamental reason.
328 eden_size = pointer_delta(from_start,
329 eden_start,
330 sizeof(char));
331 } else {
332 eden_size = MIN2(requested_eden_size,
333 pointer_delta(from_start, eden_start, sizeof(char)));
334 }
335
336 eden_end = eden_start + eden_size;
337 assert(eden_end >= eden_start, "addition overflowed");
338
339 // To may resize into from space as long as it is clear of live data.
340 // From space must remain page aligned, though, so we need to do some
341 // extra calculations.
342
343 // First calculate an optimal to-space
344 to_end = (char*)virtual_space()->high();
345 to_start = (char*)pointer_delta(to_end,
346 (char*)requested_survivor_size,
347 sizeof(char));
348
349 // Does the optimal to-space overlap from-space?
350 if (to_start < (char*)from_space()->end()) {
351 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
352
353 // Calculate the minimum offset possible for from_end
354 size_t from_size =
355 pointer_delta(from_space()->top(), from_start, sizeof(char));
356
357 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
358 if (from_size == 0) {
359 from_size = alignment;
360 } else {
361 from_size = align_size_up(from_size, alignment);
362 }
363
364 from_end = from_start + from_size;
365 assert(from_end > from_start, "addition overflow or from_size problem");
366
367 guarantee(from_end <= (char*)from_space()->end(),
368 "from_end moved to the right");
369
370 // Now update to_start with the new from_end
371 to_start = MAX2(from_end, to_start);
372 }
373
374 guarantee(to_start != to_end, "to space is zero sized");
375
376 if (PrintAdaptiveSizePolicy && Verbose) {
377 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
378 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
379 eden_start,
380 eden_end,
381 pointer_delta(eden_end, eden_start, sizeof(char)));
382 gclog_or_tty->print_cr(" [from_start .. from_end): "
383 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
384 from_start,
385 from_end,
386 pointer_delta(from_end, from_start, sizeof(char)));
387 gclog_or_tty->print_cr(" [ to_start .. to_end): "
388 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
389 to_start,
390 to_end,
391 pointer_delta( to_end, to_start, sizeof(char)));
392 }
393 } else {
394 // Eden, to, from
395 if (PrintAdaptiveSizePolicy && Verbose) {
396 gclog_or_tty->print_cr(" Eden, to, from:");
397 }
398
399 // To space gets priority over eden resizing. Note that we position
400 // to space as if we were able to resize from space, even though from
401 // space is not modified.
402 // Giving eden priority was tried and gave poorer performance.
403 to_end = (char*)pointer_delta(virtual_space()->high(),
404 (char*)requested_survivor_size,
405 sizeof(char));
406 to_end = MIN2(to_end, from_start);
407 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
408 sizeof(char));
409 // if the space sizes are to be increased by several times then
410 // 'to_start' will point beyond the young generation. In this case
411 // 'to_start' should be adjusted.
412 to_start = MAX2(to_start, eden_start + alignment);
413
414 // Compute how big eden can be, then adjust end.
415 // See comments above on calculating eden_end.
416 size_t eden_size;
417 if (maintain_minimum) {
418 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
419 } else {
420 eden_size = MIN2(requested_eden_size,
421 pointer_delta(to_start, eden_start, sizeof(char)));
422 }
423 eden_end = eden_start + eden_size;
424 assert(eden_end >= eden_start, "addition overflowed");
425
426 // Don't let eden shrink down to 0 or less.
427 eden_end = MAX2(eden_end, eden_start + alignment);
428 to_start = MAX2(to_start, eden_end);
429
430 if (PrintAdaptiveSizePolicy && Verbose) {
431 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
432 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
433 eden_start,
434 eden_end,
435 pointer_delta(eden_end, eden_start, sizeof(char)));
436 gclog_or_tty->print_cr(" [ to_start .. to_end): "
437 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
438 to_start,
439 to_end,
440 pointer_delta( to_end, to_start, sizeof(char)));
441 gclog_or_tty->print_cr(" [from_start .. from_end): "
442 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
443 from_start,
444 from_end,
445 pointer_delta(from_end, from_start, sizeof(char)));
446 }
447 }
448
449
450 guarantee((HeapWord*)from_start <= from_space()->bottom(),
451 "from start moved to the right");
452 guarantee((HeapWord*)from_end >= from_space()->top(),
453 "from end moved into live data");
454 assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
455 assert(is_object_aligned((intptr_t)from_start), "checking alignment");
456 assert(is_object_aligned((intptr_t)to_start), "checking alignment");
457
458 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
459 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
460 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
461
462 // Let's make sure the call to initialize doesn't reset "top"!
463 DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
464
465 // For PrintAdaptiveSizePolicy block below
466 size_t old_from = from_space()->capacity_in_bytes();
467 size_t old_to = to_space()->capacity_in_bytes();
468
469 if (ZapUnusedHeapArea) {
470 // NUMA is a special case because a numa space is not mangled
471 // in order to not prematurely bind its address to memory to
472 // the wrong memory (i.e., don't want the GC thread to first
473 // touch the memory). The survivor spaces are not numa
474 // spaces and are mangled.
475 if (UseNUMA) {
476 if (eden_from_to_order) {
477 mangle_survivors(from_space(), fromMR, to_space(), toMR);
478 } else {
479 mangle_survivors(to_space(), toMR, from_space(), fromMR);
480 }
481 }
482
483 // If not mangling the spaces, do some checking to verify that
484 // the spaces are already mangled.
485 // The spaces should be correctly mangled at this point so
486 // do some checking here. Note that they are not being mangled
487 // in the calls to initialize().
488 // Must check mangling before the spaces are reshaped. Otherwise,
489 // the bottom or end of one space may have moved into an area
490 // covered by another space and a failure of the check may
491 // not correctly indicate which space is not properly mangled.
492
493 HeapWord* limit = (HeapWord*) virtual_space()->high();
494 eden_space()->check_mangled_unused_area(limit);
495 from_space()->check_mangled_unused_area(limit);
496 to_space()->check_mangled_unused_area(limit);
497 }
498 // When an existing space is being initialized, it is not
499 // mangled because the space has been previously mangled.
500 eden_space()->initialize(edenMR,
501 SpaceDecorator::Clear,
502 SpaceDecorator::DontMangle);
503 to_space()->initialize(toMR,
504 SpaceDecorator::Clear,
505 SpaceDecorator::DontMangle);
506 from_space()->initialize(fromMR,
507 SpaceDecorator::DontClear,
508 SpaceDecorator::DontMangle);
509
510 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
511
512 assert(from_space()->top() == old_from_top, "from top changed!");
513
514 if (PrintAdaptiveSizePolicy) {
515 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
516 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
517
518 gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
519 "collection: %d "
520 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
521 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
522 heap->total_collections(),
523 old_from, old_to,
524 from_space()->capacity_in_bytes(),
525 to_space()->capacity_in_bytes());
526 gclog_or_tty->cr();
527 }
528 space_invariants();
529 }
530 void ASPSYoungGen::reset_after_change() {
531 assert_locked_or_safepoint(Heap_lock);
532
533 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
534 (HeapWord*)virtual_space()->high_boundary());
535 PSScavenge::reference_processor()->set_span(_reserved);
536
537 HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
538 HeapWord* eden_bottom = eden_space()->bottom();
539 if (new_eden_bottom != eden_bottom) {
540 MemRegion eden_mr(new_eden_bottom, eden_space()->end());
541 eden_space()->initialize(eden_mr,
542 SpaceDecorator::Clear,
543 SpaceDecorator::Mangle);
544 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
545 }
546 MemRegion cmr((HeapWord*)virtual_space()->low(),
547 (HeapWord*)virtual_space()->high());
548 Universe::heap()->barrier_set()->resize_covered_region(cmr);
549
550 space_invariants();
551 }