1 /*
2 * Copyright (c) 2001, 2019, 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/mutableNUMASpace.hpp"
27 #include "gc/parallel/parallelScavengeHeap.hpp"
28 #include "gc/parallel/psMarkSweepDecorator.hpp"
29 #include "gc/parallel/psScavenge.hpp"
30 #include "gc/parallel/psYoungGen.hpp"
31 #include "gc/shared/gcUtil.hpp"
32 #include "gc/shared/genArguments.hpp"
33 #include "gc/shared/spaceDecorator.hpp"
34 #include "logging/log.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "runtime/java.hpp"
37 #include "utilities/align.hpp"
38
39 PSYoungGen::PSYoungGen(size_t initial_size, size_t min_size, size_t max_size) :
40 _reserved(),
41 _virtual_space(NULL),
42 _eden_space(NULL),
43 _from_space(NULL),
44 _to_space(NULL),
45 _eden_mark_sweep(NULL),
46 _from_mark_sweep(NULL),
47 _to_mark_sweep(NULL),
48 _init_gen_size(initial_size),
49 _min_gen_size(min_size),
50 _max_gen_size(max_size),
51 _gen_counters(NULL),
52 _eden_counters(NULL),
53 _from_counters(NULL),
54 _to_counters(NULL)
55 {}
56
57 void PSYoungGen::initialize_virtual_space(ReservedSpace rs, size_t alignment) {
58 assert(_init_gen_size != 0, "Should have a finite size");
59 _virtual_space = new PSVirtualSpace(rs, alignment);
60 if (!virtual_space()->expand_by(_init_gen_size)) {
61 vm_exit_during_initialization("Could not reserve enough space for "
62 "object heap");
63 }
64 }
65
66 void PSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
67 initialize_virtual_space(rs, alignment);
68 initialize_work();
69 }
70
71 void PSYoungGen::initialize_work() {
72
73 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
74 (HeapWord*)virtual_space()->high_boundary());
75
76 MemRegion cmr((HeapWord*)virtual_space()->low(),
77 (HeapWord*)virtual_space()->high());
78 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
79
80 if (ZapUnusedHeapArea) {
81 // Mangle newly committed space immediately because it
82 // can be done here more simply that after the new
83 // spaces have been computed.
84 SpaceMangler::mangle_region(cmr);
85 }
86
87 if (UseNUMA) {
88 _eden_space = new MutableNUMASpace(virtual_space()->alignment());
89 } else {
90 _eden_space = new MutableSpace(virtual_space()->alignment());
91 }
92 _from_space = new MutableSpace(virtual_space()->alignment());
93 _to_space = new MutableSpace(virtual_space()->alignment());
94
95 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) {
96 vm_exit_during_initialization("Could not allocate a young gen space");
97 }
98
99 // Allocate the mark sweep views of spaces
100 _eden_mark_sweep =
101 new PSMarkSweepDecorator(_eden_space, NULL, MarkSweepDeadRatio);
102 _from_mark_sweep =
103 new PSMarkSweepDecorator(_from_space, NULL, MarkSweepDeadRatio);
104 _to_mark_sweep =
105 new PSMarkSweepDecorator(_to_space, NULL, MarkSweepDeadRatio);
106
107 if (_eden_mark_sweep == NULL ||
108 _from_mark_sweep == NULL ||
109 _to_mark_sweep == NULL) {
110 vm_exit_during_initialization("Could not complete allocation"
111 " of the young generation");
112 }
113
114 // Generation Counters - generation 0, 3 subspaces
115 _gen_counters = new PSGenerationCounters("new", 0, 3, _min_gen_size,
116 _max_gen_size, _virtual_space);
117
118 // Compute maximum space sizes for performance counters
119 size_t alignment = SpaceAlignment;
120 size_t size = virtual_space()->reserved_size();
121
122 size_t max_survivor_size;
123 size_t max_eden_size;
124
125 if (UseAdaptiveSizePolicy) {
126 max_survivor_size = size / MinSurvivorRatio;
127
128 // round the survivor space size down to the nearest alignment
129 // and make sure its size is greater than 0.
130 max_survivor_size = align_down(max_survivor_size, alignment);
131 max_survivor_size = MAX2(max_survivor_size, alignment);
132
133 // set the maximum size of eden to be the size of the young gen
134 // less two times the minimum survivor size. The minimum survivor
135 // size for UseAdaptiveSizePolicy is one alignment.
136 max_eden_size = size - 2 * alignment;
137 } else {
138 max_survivor_size = size / InitialSurvivorRatio;
139
140 // round the survivor space size down to the nearest alignment
141 // and make sure its size is greater than 0.
142 max_survivor_size = align_down(max_survivor_size, alignment);
143 max_survivor_size = MAX2(max_survivor_size, alignment);
144
145 // set the maximum size of eden to be the size of the young gen
146 // less two times the survivor size when the generation is 100%
147 // committed. The minimum survivor size for -UseAdaptiveSizePolicy
148 // is dependent on the committed portion (current capacity) of the
149 // generation - the less space committed, the smaller the survivor
150 // space, possibly as small as an alignment. However, we are interested
151 // in the case where the young generation is 100% committed, as this
152 // is the point where eden reaches its maximum size. At this point,
153 // the size of a survivor space is max_survivor_size.
154 max_eden_size = size - 2 * max_survivor_size;
155 }
156
157 _eden_counters = new SpaceCounters("eden", 0, max_eden_size, _eden_space,
158 _gen_counters);
159 _from_counters = new SpaceCounters("s0", 1, max_survivor_size, _from_space,
160 _gen_counters);
161 _to_counters = new SpaceCounters("s1", 2, max_survivor_size, _to_space,
162 _gen_counters);
163
164 compute_initial_space_boundaries();
165 }
166
167 void PSYoungGen::compute_initial_space_boundaries() {
168 // Compute sizes
169 size_t size = virtual_space()->committed_size();
170 assert(size >= 3 * SpaceAlignment, "Young space is not large enough for eden + 2 survivors");
171
172 size_t survivor_size = size / InitialSurvivorRatio;
173 survivor_size = align_down(survivor_size, SpaceAlignment);
174 // ... but never less than an alignment
175 survivor_size = MAX2(survivor_size, SpaceAlignment);
176
177 // Young generation is eden + 2 survivor spaces
178 size_t eden_size = size - (2 * survivor_size);
179
180 // Now go ahead and set 'em.
181 set_space_boundaries(eden_size, survivor_size);
182 space_invariants();
183
184 if (UsePerfData) {
185 _eden_counters->update_capacity();
186 _from_counters->update_capacity();
187 _to_counters->update_capacity();
188 }
189 }
190
191 void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) {
192 assert(eden_size < virtual_space()->committed_size(), "just checking");
193 assert(eden_size > 0 && survivor_size > 0, "just checking");
194
195 // Initial layout is Eden, to, from. After swapping survivor spaces,
196 // that leaves us with Eden, from, to, which is step one in our two
197 // step resize-with-live-data procedure.
198 char *eden_start = virtual_space()->low();
199 char *to_start = eden_start + eden_size;
200 char *from_start = to_start + survivor_size;
201 char *from_end = from_start + survivor_size;
202
203 assert(from_end == virtual_space()->high(), "just checking");
204 assert(is_object_aligned(eden_start), "checking alignment");
205 assert(is_object_aligned(to_start), "checking alignment");
206 assert(is_object_aligned(from_start), "checking alignment");
207
208 MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start);
209 MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start);
210 MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end);
211
212 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea);
213 to_space()->initialize(to_mr , true, ZapUnusedHeapArea);
214 from_space()->initialize(from_mr, true, ZapUnusedHeapArea);
215 }
216
217 #ifndef PRODUCT
218 void PSYoungGen::space_invariants() {
219 // Currently, our eden size cannot shrink to zero
220 guarantee(eden_space()->capacity_in_bytes() >= SpaceAlignment, "eden too small");
221 guarantee(from_space()->capacity_in_bytes() >= SpaceAlignment, "from too small");
222 guarantee(to_space()->capacity_in_bytes() >= SpaceAlignment, "to too small");
223
224 // Relationship of spaces to each other
225 char* eden_start = (char*)eden_space()->bottom();
226 char* eden_end = (char*)eden_space()->end();
227 char* from_start = (char*)from_space()->bottom();
228 char* from_end = (char*)from_space()->end();
229 char* to_start = (char*)to_space()->bottom();
230 char* to_end = (char*)to_space()->end();
231
232 guarantee(eden_start >= virtual_space()->low(), "eden bottom");
233 guarantee(eden_start < eden_end, "eden space consistency");
234 guarantee(from_start < from_end, "from space consistency");
235 guarantee(to_start < to_end, "to space consistency");
236
237 // Check whether from space is below to space
238 if (from_start < to_start) {
239 // Eden, from, to
240 guarantee(eden_end <= from_start, "eden/from boundary");
241 guarantee(from_end <= to_start, "from/to boundary");
242 guarantee(to_end <= virtual_space()->high(), "to end");
243 } else {
244 // Eden, to, from
245 guarantee(eden_end <= to_start, "eden/to boundary");
246 guarantee(to_end <= from_start, "to/from boundary");
247 guarantee(from_end <= virtual_space()->high(), "from end");
248 }
249
250 // More checks that the virtual space is consistent with the spaces
251 assert(virtual_space()->committed_size() >=
252 (eden_space()->capacity_in_bytes() +
253 to_space()->capacity_in_bytes() +
254 from_space()->capacity_in_bytes()), "Committed size is inconsistent");
255 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
256 "Space invariant");
257 char* eden_top = (char*)eden_space()->top();
258 char* from_top = (char*)from_space()->top();
259 char* to_top = (char*)to_space()->top();
260 assert(eden_top <= virtual_space()->high(), "eden top");
261 assert(from_top <= virtual_space()->high(), "from top");
262 assert(to_top <= virtual_space()->high(), "to top");
263
264 virtual_space()->verify();
265 }
266 #endif
267
268 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) {
269 // Resize the generation if needed. If the generation resize
270 // reports false, do not attempt to resize the spaces.
271 if (resize_generation(eden_size, survivor_size)) {
272 // Then we lay out the spaces inside the generation
273 resize_spaces(eden_size, survivor_size);
274
275 space_invariants();
276
277 log_trace(gc, ergo)("Young generation size: "
278 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
279 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
280 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
281 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(),
282 _max_gen_size, min_gen_size());
283 }
284 }
285
286
287 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
288 const size_t alignment = virtual_space()->alignment();
289 size_t orig_size = virtual_space()->committed_size();
290 bool size_changed = false;
291
292 // There used to be this guarantee there.
293 // guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments");
294 // Code below forces this requirement. In addition the desired eden
295 // size and desired survivor sizes are desired goals and may
296 // exceed the total generation size.
297
298 assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking");
299
300 // Adjust new generation size
301 const size_t eden_plus_survivors =
302 align_up(eden_size + 2 * survivor_size, alignment);
303 size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_size()),
304 min_gen_size());
305 assert(desired_size <= max_size(), "just checking");
306
307 if (desired_size > orig_size) {
308 // Grow the generation
309 size_t change = desired_size - orig_size;
310 assert(change % alignment == 0, "just checking");
311 HeapWord* prev_high = (HeapWord*) virtual_space()->high();
312 if (!virtual_space()->expand_by(change)) {
313 return false; // Error if we fail to resize!
314 }
315 if (ZapUnusedHeapArea) {
316 // Mangle newly committed space immediately because it
317 // can be done here more simply that after the new
318 // spaces have been computed.
319 HeapWord* new_high = (HeapWord*) virtual_space()->high();
320 MemRegion mangle_region(prev_high, new_high);
321 SpaceMangler::mangle_region(mangle_region);
322 }
323 size_changed = true;
324 } else if (desired_size < orig_size) {
325 size_t desired_change = orig_size - desired_size;
326 assert(desired_change % alignment == 0, "just checking");
327
328 desired_change = limit_gen_shrink(desired_change);
329
330 if (desired_change > 0) {
331 virtual_space()->shrink_by(desired_change);
332 reset_survivors_after_shrink();
333
334 size_changed = true;
335 }
336 } else {
337 if (orig_size == gen_size_limit()) {
338 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
339 } else if (orig_size == min_gen_size()) {
340 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
341 }
342 }
343
344 if (size_changed) {
345 post_resize();
346 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
347 orig_size/K, virtual_space()->committed_size()/K);
348 }
349
350 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
351 virtual_space()->committed_size() == max_size(), "Sanity");
352
353 return true;
354 }
355
356 #ifndef PRODUCT
357 // In the numa case eden is not mangled so a survivor space
358 // moving into a region previously occupied by a survivor
359 // may find an unmangled region. Also in the PS case eden
360 // to-space and from-space may not touch (i.e., there may be
361 // gaps between them due to movement while resizing the
362 // spaces). Those gaps must be mangled.
363 void PSYoungGen::mangle_survivors(MutableSpace* s1,
364 MemRegion s1MR,
365 MutableSpace* s2,
366 MemRegion s2MR) {
367 // Check eden and gap between eden and from-space, in deciding
368 // what to mangle in from-space. Check the gap between from-space
369 // and to-space when deciding what to mangle.
370 //
371 // +--------+ +----+ +---+
372 // | eden | |s1 | |s2 |
373 // +--------+ +----+ +---+
374 // +-------+ +-----+
375 // |s1MR | |s2MR |
376 // +-------+ +-----+
377 // All of survivor-space is properly mangled so find the
378 // upper bound on the mangling for any portion above current s1.
379 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end());
380 MemRegion delta1_left;
381 if (s1MR.start() < delta_end) {
382 delta1_left = MemRegion(s1MR.start(), delta_end);
383 s1->mangle_region(delta1_left);
384 }
385 // Find any portion to the right of the current s1.
386 HeapWord* delta_start = MAX2(s1->end(), s1MR.start());
387 MemRegion delta1_right;
388 if (delta_start < s1MR.end()) {
389 delta1_right = MemRegion(delta_start, s1MR.end());
390 s1->mangle_region(delta1_right);
391 }
392
393 // Similarly for the second survivor space except that
394 // any of the new region that overlaps with the current
395 // region of the first survivor space has already been
396 // mangled.
397 delta_end = MIN2(s2->bottom(), s2MR.end());
398 delta_start = MAX2(s2MR.start(), s1->end());
399 MemRegion delta2_left;
400 if (s2MR.start() < delta_end) {
401 delta2_left = MemRegion(s2MR.start(), delta_end);
402 s2->mangle_region(delta2_left);
403 }
404 delta_start = MAX2(s2->end(), s2MR.start());
405 MemRegion delta2_right;
406 if (delta_start < s2MR.end()) {
407 s2->mangle_region(delta2_right);
408 }
409
410 // s1
411 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
412 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
413 p2i(s1->bottom()), p2i(s1->end()),
414 p2i(s1MR.start()), p2i(s1MR.end()));
415 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
416 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
417 p2i(delta1_left.start()), p2i(delta1_left.end()),
418 p2i(delta1_right.start()), p2i(delta1_right.end()));
419
420 // s2
421 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
422 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
423 p2i(s2->bottom()), p2i(s2->end()),
424 p2i(s2MR.start()), p2i(s2MR.end()));
425 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
426 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
427 p2i(delta2_left.start()), p2i(delta2_left.end()),
428 p2i(delta2_right.start()), p2i(delta2_right.end()));
429 }
430 #endif // NOT PRODUCT
431
432 void PSYoungGen::resize_spaces(size_t requested_eden_size,
433 size_t requested_survivor_size) {
434 assert(UseAdaptiveSizePolicy, "sanity check");
435 assert(requested_eden_size > 0 && requested_survivor_size > 0,
436 "just checking");
437
438 // We require eden and to space to be empty
439 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
440 return;
441 }
442
443 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")",
444 requested_eden_size, requested_survivor_size);
445 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
446 p2i(eden_space()->bottom()),
447 p2i(eden_space()->end()),
448 pointer_delta(eden_space()->end(),
449 eden_space()->bottom(),
450 sizeof(char)));
451 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
452 p2i(from_space()->bottom()),
453 p2i(from_space()->end()),
454 pointer_delta(from_space()->end(),
455 from_space()->bottom(),
456 sizeof(char)));
457 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
458 p2i(to_space()->bottom()),
459 p2i(to_space()->end()),
460 pointer_delta( to_space()->end(),
461 to_space()->bottom(),
462 sizeof(char)));
463
464 // There's nothing to do if the new sizes are the same as the current
465 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
466 requested_survivor_size == from_space()->capacity_in_bytes() &&
467 requested_eden_size == eden_space()->capacity_in_bytes()) {
468 log_trace(gc, ergo)(" capacities are the right sizes, returning");
469 return;
470 }
471
472 char* eden_start = (char*)eden_space()->bottom();
473 char* eden_end = (char*)eden_space()->end();
474 char* from_start = (char*)from_space()->bottom();
475 char* from_end = (char*)from_space()->end();
476 char* to_start = (char*)to_space()->bottom();
477 char* to_end = (char*)to_space()->end();
478
479 const bool maintain_minimum =
480 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
481
482 bool eden_from_to_order = from_start < to_start;
483 // Check whether from space is below to space
484 if (eden_from_to_order) {
485 // Eden, from, to
486 eden_from_to_order = true;
487 log_trace(gc, ergo)(" Eden, from, to:");
488
489 // Set eden
490 // "requested_eden_size" is a goal for the size of eden
491 // and may not be attainable. "eden_size" below is
492 // calculated based on the location of from-space and
493 // the goal for the size of eden. from-space is
494 // fixed in place because it contains live data.
495 // The calculation is done this way to avoid 32bit
496 // overflow (i.e., eden_start + requested_eden_size
497 // may too large for representation in 32bits).
498 size_t eden_size;
499 if (maintain_minimum) {
500 // Only make eden larger than the requested size if
501 // the minimum size of the generation has to be maintained.
502 // This could be done in general but policy at a higher
503 // level is determining a requested size for eden and that
504 // should be honored unless there is a fundamental reason.
505 eden_size = pointer_delta(from_start,
506 eden_start,
507 sizeof(char));
508 } else {
509 eden_size = MIN2(requested_eden_size,
510 pointer_delta(from_start, eden_start, sizeof(char)));
511 }
512
513 eden_end = eden_start + eden_size;
514 assert(eden_end >= eden_start, "addition overflowed");
515
516 // To may resize into from space as long as it is clear of live data.
517 // From space must remain page aligned, though, so we need to do some
518 // extra calculations.
519
520 // First calculate an optimal to-space
521 to_end = (char*)virtual_space()->high();
522 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
523 sizeof(char));
524
525 // Does the optimal to-space overlap from-space?
526 if (to_start < (char*)from_space()->end()) {
527 // Calculate the minimum offset possible for from_end
528 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
529
530 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
531 if (from_size == 0) {
532 from_size = SpaceAlignment;
533 } else {
534 from_size = align_up(from_size, SpaceAlignment);
535 }
536
537 from_end = from_start + from_size;
538 assert(from_end > from_start, "addition overflow or from_size problem");
539
540 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
541
542 // Now update to_start with the new from_end
543 to_start = MAX2(from_end, to_start);
544 }
545
546 guarantee(to_start != to_end, "to space is zero sized");
547
548 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
549 p2i(eden_start),
550 p2i(eden_end),
551 pointer_delta(eden_end, eden_start, sizeof(char)));
552 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
553 p2i(from_start),
554 p2i(from_end),
555 pointer_delta(from_end, from_start, sizeof(char)));
556 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
557 p2i(to_start),
558 p2i(to_end),
559 pointer_delta( to_end, to_start, sizeof(char)));
560 } else {
561 // Eden, to, from
562 log_trace(gc, ergo)(" Eden, to, from:");
563
564 // To space gets priority over eden resizing. Note that we position
565 // to space as if we were able to resize from space, even though from
566 // space is not modified.
567 // Giving eden priority was tried and gave poorer performance.
568 to_end = (char*)pointer_delta(virtual_space()->high(),
569 (char*)requested_survivor_size,
570 sizeof(char));
571 to_end = MIN2(to_end, from_start);
572 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
573 sizeof(char));
574 // if the space sizes are to be increased by several times then
575 // 'to_start' will point beyond the young generation. In this case
576 // 'to_start' should be adjusted.
577 to_start = MAX2(to_start, eden_start + SpaceAlignment);
578
579 // Compute how big eden can be, then adjust end.
580 // See comments above on calculating eden_end.
581 size_t eden_size;
582 if (maintain_minimum) {
583 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
584 } else {
585 eden_size = MIN2(requested_eden_size,
586 pointer_delta(to_start, eden_start, sizeof(char)));
587 }
588 eden_end = eden_start + eden_size;
589 assert(eden_end >= eden_start, "addition overflowed");
590
591 // Could choose to not let eden shrink
592 // to_start = MAX2(to_start, eden_end);
593
594 // Don't let eden shrink down to 0 or less.
595 eden_end = MAX2(eden_end, eden_start + SpaceAlignment);
596 to_start = MAX2(to_start, eden_end);
597
598 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
599 p2i(eden_start),
600 p2i(eden_end),
601 pointer_delta(eden_end, eden_start, sizeof(char)));
602 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
603 p2i(to_start),
604 p2i(to_end),
605 pointer_delta( to_end, to_start, sizeof(char)));
606 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
607 p2i(from_start),
608 p2i(from_end),
609 pointer_delta(from_end, from_start, sizeof(char)));
610 }
611
612
613 guarantee((HeapWord*)from_start <= from_space()->bottom(),
614 "from start moved to the right");
615 guarantee((HeapWord*)from_end >= from_space()->top(),
616 "from end moved into live data");
617 assert(is_object_aligned(eden_start), "checking alignment");
618 assert(is_object_aligned(from_start), "checking alignment");
619 assert(is_object_aligned(to_start), "checking alignment");
620
621 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
622 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
623 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
624
625 // Let's make sure the call to initialize doesn't reset "top"!
626 HeapWord* old_from_top = from_space()->top();
627
628 // For logging block below
629 size_t old_from = from_space()->capacity_in_bytes();
630 size_t old_to = to_space()->capacity_in_bytes();
631
632 if (ZapUnusedHeapArea) {
633 // NUMA is a special case because a numa space is not mangled
634 // in order to not prematurely bind its address to memory to
635 // the wrong memory (i.e., don't want the GC thread to first
636 // touch the memory). The survivor spaces are not numa
637 // spaces and are mangled.
638 if (UseNUMA) {
639 if (eden_from_to_order) {
640 mangle_survivors(from_space(), fromMR, to_space(), toMR);
641 } else {
642 mangle_survivors(to_space(), toMR, from_space(), fromMR);
643 }
644 }
645
646 // If not mangling the spaces, do some checking to verify that
647 // the spaces are already mangled.
648 // The spaces should be correctly mangled at this point so
649 // do some checking here. Note that they are not being mangled
650 // in the calls to initialize().
651 // Must check mangling before the spaces are reshaped. Otherwise,
652 // the bottom or end of one space may have moved into an area
653 // covered by another space and a failure of the check may
654 // not correctly indicate which space is not properly mangled.
655 HeapWord* limit = (HeapWord*) virtual_space()->high();
656 eden_space()->check_mangled_unused_area(limit);
657 from_space()->check_mangled_unused_area(limit);
658 to_space()->check_mangled_unused_area(limit);
659 }
660 // When an existing space is being initialized, it is not
661 // mangled because the space has been previously mangled.
662 eden_space()->initialize(edenMR,
663 SpaceDecorator::Clear,
664 SpaceDecorator::DontMangle);
665 to_space()->initialize(toMR,
666 SpaceDecorator::Clear,
667 SpaceDecorator::DontMangle);
668 from_space()->initialize(fromMR,
669 SpaceDecorator::DontClear,
670 SpaceDecorator::DontMangle);
671
672 assert(from_space()->top() == old_from_top, "from top changed!");
673
674 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ",
675 ParallelScavengeHeap::heap()->total_collections(),
676 old_from, old_to,
677 from_space()->capacity_in_bytes(),
678 to_space()->capacity_in_bytes());
679 }
680
681 void PSYoungGen::swap_spaces() {
682 MutableSpace* s = from_space();
683 _from_space = to_space();
684 _to_space = s;
685
686 // Now update the decorators.
687 PSMarkSweepDecorator* md = from_mark_sweep();
688 _from_mark_sweep = to_mark_sweep();
689 _to_mark_sweep = md;
690
691 assert(from_mark_sweep()->space() == from_space(), "Sanity");
692 assert(to_mark_sweep()->space() == to_space(), "Sanity");
693 }
694
695 size_t PSYoungGen::capacity_in_bytes() const {
696 return eden_space()->capacity_in_bytes()
697 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge
698 }
699
700
701 size_t PSYoungGen::used_in_bytes() const {
702 return eden_space()->used_in_bytes()
703 + from_space()->used_in_bytes(); // to_space() is only used during scavenge
704 }
705
706
707 size_t PSYoungGen::free_in_bytes() const {
708 return eden_space()->free_in_bytes()
709 + from_space()->free_in_bytes(); // to_space() is only used during scavenge
710 }
711
712 size_t PSYoungGen::capacity_in_words() const {
713 return eden_space()->capacity_in_words()
714 + from_space()->capacity_in_words(); // to_space() is only used during scavenge
715 }
716
717
718 size_t PSYoungGen::used_in_words() const {
719 return eden_space()->used_in_words()
720 + from_space()->used_in_words(); // to_space() is only used during scavenge
721 }
722
723
724 size_t PSYoungGen::free_in_words() const {
725 return eden_space()->free_in_words()
726 + from_space()->free_in_words(); // to_space() is only used during scavenge
727 }
728
729 void PSYoungGen::object_iterate(ObjectClosure* blk) {
730 eden_space()->object_iterate(blk);
731 from_space()->object_iterate(blk);
732 to_space()->object_iterate(blk);
733 }
734
735 #if INCLUDE_SERIALGC
736
737 void PSYoungGen::precompact() {
738 eden_mark_sweep()->precompact();
739 from_mark_sweep()->precompact();
740 to_mark_sweep()->precompact();
741 }
742
743 void PSYoungGen::adjust_pointers() {
744 eden_mark_sweep()->adjust_pointers();
745 from_mark_sweep()->adjust_pointers();
746 to_mark_sweep()->adjust_pointers();
747 }
748
749 void PSYoungGen::compact() {
750 eden_mark_sweep()->compact(ZapUnusedHeapArea);
751 from_mark_sweep()->compact(ZapUnusedHeapArea);
752 // Mark sweep stores preserved markWords in to space, don't disturb!
753 to_mark_sweep()->compact(false);
754 }
755
756 #endif // INCLUDE_SERIALGC
757
758 void PSYoungGen::print() const { print_on(tty); }
759 void PSYoungGen::print_on(outputStream* st) const {
760 st->print(" %-15s", "PSYoungGen");
761 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
762 capacity_in_bytes()/K, used_in_bytes()/K);
763 virtual_space()->print_space_boundaries_on(st);
764 st->print(" eden"); eden_space()->print_on(st);
765 st->print(" from"); from_space()->print_on(st);
766 st->print(" to "); to_space()->print_on(st);
767 }
768
769 size_t PSYoungGen::available_for_expansion() {
770 ShouldNotReachHere();
771 return 0;
772 }
773
774 size_t PSYoungGen::available_for_contraction() {
775 ShouldNotReachHere();
776 return 0;
777 }
778
779 size_t PSYoungGen::available_to_min_gen() {
780 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
781 return virtual_space()->committed_size() - min_gen_size();
782 }
783
784 // This method assumes that from-space has live data and that
785 // any shrinkage of the young gen is limited by location of
786 // from-space.
787 size_t PSYoungGen::available_to_live() {
788 size_t delta_in_survivor = 0;
789 MutableSpace* space_shrinking = NULL;
790 if (from_space()->end() > to_space()->end()) {
791 space_shrinking = from_space();
792 } else {
793 space_shrinking = to_space();
794 }
795
796 // Include any space that is committed but not included in
797 // the survivor spaces.
798 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
799 "Survivor space beyond high end");
800 size_t unused_committed = pointer_delta(virtual_space()->high(),
801 space_shrinking->end(), sizeof(char));
802
803 if (space_shrinking->is_empty()) {
804 // Don't let the space shrink to 0
805 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment,
806 "Space is too small");
807 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment;
808 } else {
809 delta_in_survivor = pointer_delta(space_shrinking->end(),
810 space_shrinking->top(),
811 sizeof(char));
812 }
813
814 size_t delta_in_bytes = unused_committed + delta_in_survivor;
815 delta_in_bytes = align_down(delta_in_bytes, GenAlignment);
816 return delta_in_bytes;
817 }
818
819 // Return the number of bytes available for resizing down the young
820 // generation. This is the minimum of
821 // input "bytes"
822 // bytes to the minimum young gen size
823 // bytes to the size currently being used + some small extra
824 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
825 // Allow shrinkage into the current eden but keep eden large enough
826 // to maintain the minimum young gen size
827 bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
828 return align_down(bytes, virtual_space()->alignment());
829 }
830
831 void PSYoungGen::reset_after_change() {
832 ShouldNotReachHere();
833 }
834
835 void PSYoungGen::reset_survivors_after_shrink() {
836 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
837 (HeapWord*)virtual_space()->high_boundary());
838 PSScavenge::set_subject_to_discovery_span(_reserved);
839
840 MutableSpace* space_shrinking = NULL;
841 if (from_space()->end() > to_space()->end()) {
842 space_shrinking = from_space();
843 } else {
844 space_shrinking = to_space();
845 }
846
847 HeapWord* new_end = (HeapWord*)virtual_space()->high();
848 assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
849 // Was there a shrink of the survivor space?
850 if (new_end < space_shrinking->end()) {
851 MemRegion mr(space_shrinking->bottom(), new_end);
852 space_shrinking->initialize(mr,
853 SpaceDecorator::DontClear,
854 SpaceDecorator::Mangle);
855 }
856 }
857
858 // This method currently does not expect to expand into eden (i.e.,
859 // the virtual space boundaries is expected to be consistent
860 // with the eden boundaries..
861 void PSYoungGen::post_resize() {
862 assert_locked_or_safepoint(Heap_lock);
863 assert((eden_space()->bottom() < to_space()->bottom()) &&
864 (eden_space()->bottom() < from_space()->bottom()),
865 "Eden is assumed to be below the survivor spaces");
866
867 MemRegion cmr((HeapWord*)virtual_space()->low(),
868 (HeapWord*)virtual_space()->high());
869 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
870 space_invariants();
871 }
872
873
874
875 void PSYoungGen::update_counters() {
876 if (UsePerfData) {
877 _eden_counters->update_all();
878 _from_counters->update_all();
879 _to_counters->update_all();
880 _gen_counters->update_all();
881 }
882 }
883
884 void PSYoungGen::verify() {
885 eden_space()->verify();
886 from_space()->verify();
887 to_space()->verify();
888 }
889
890 #ifndef PRODUCT
891 void PSYoungGen::record_spaces_top() {
892 assert(ZapUnusedHeapArea, "Not mangling unused space");
893 eden_space()->set_top_for_allocations();
894 from_space()->set_top_for_allocations();
895 to_space()->set_top_for_allocations();
896 }
897 #endif