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.inline.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 = clamp(eden_plus_survivors, min_gen_size(), max_size());
304 assert(desired_size <= max_size(), "just checking");
305
306 if (desired_size > orig_size) {
307 // Grow the generation
308 size_t change = desired_size - orig_size;
309 assert(change % alignment == 0, "just checking");
310 HeapWord* prev_high = (HeapWord*) virtual_space()->high();
311 if (!virtual_space()->expand_by(change)) {
312 return false; // Error if we fail to resize!
313 }
314 if (ZapUnusedHeapArea) {
315 // Mangle newly committed space immediately because it
316 // can be done here more simply that after the new
317 // spaces have been computed.
318 HeapWord* new_high = (HeapWord*) virtual_space()->high();
319 MemRegion mangle_region(prev_high, new_high);
320 SpaceMangler::mangle_region(mangle_region);
321 }
322 size_changed = true;
323 } else if (desired_size < orig_size) {
324 size_t desired_change = orig_size - desired_size;
325 assert(desired_change % alignment == 0, "just checking");
326
327 desired_change = limit_gen_shrink(desired_change);
328
329 if (desired_change > 0) {
330 virtual_space()->shrink_by(desired_change);
331 reset_survivors_after_shrink();
332
333 size_changed = true;
334 }
335 } else {
336 if (orig_size == gen_size_limit()) {
337 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
338 } else if (orig_size == min_gen_size()) {
339 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
340 }
341 }
342
343 if (size_changed) {
344 post_resize();
345 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
346 orig_size/K, virtual_space()->committed_size()/K);
347 }
348
349 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
350 virtual_space()->committed_size() == max_size(), "Sanity");
351
352 return true;
353 }
354
355 #ifndef PRODUCT
356 // In the numa case eden is not mangled so a survivor space
357 // moving into a region previously occupied by a survivor
358 // may find an unmangled region. Also in the PS case eden
359 // to-space and from-space may not touch (i.e., there may be
360 // gaps between them due to movement while resizing the
361 // spaces). Those gaps must be mangled.
362 void PSYoungGen::mangle_survivors(MutableSpace* s1,
363 MemRegion s1MR,
364 MutableSpace* s2,
365 MemRegion s2MR) {
366 // Check eden and gap between eden and from-space, in deciding
367 // what to mangle in from-space. Check the gap between from-space
368 // and to-space when deciding what to mangle.
369 //
370 // +--------+ +----+ +---+
371 // | eden | |s1 | |s2 |
372 // +--------+ +----+ +---+
373 // +-------+ +-----+
374 // |s1MR | |s2MR |
375 // +-------+ +-----+
376 // All of survivor-space is properly mangled so find the
377 // upper bound on the mangling for any portion above current s1.
378 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end());
379 MemRegion delta1_left;
380 if (s1MR.start() < delta_end) {
381 delta1_left = MemRegion(s1MR.start(), delta_end);
382 s1->mangle_region(delta1_left);
383 }
384 // Find any portion to the right of the current s1.
385 HeapWord* delta_start = MAX2(s1->end(), s1MR.start());
386 MemRegion delta1_right;
387 if (delta_start < s1MR.end()) {
388 delta1_right = MemRegion(delta_start, s1MR.end());
389 s1->mangle_region(delta1_right);
390 }
391
392 // Similarly for the second survivor space except that
393 // any of the new region that overlaps with the current
394 // region of the first survivor space has already been
395 // mangled.
396 delta_end = MIN2(s2->bottom(), s2MR.end());
397 delta_start = MAX2(s2MR.start(), s1->end());
398 MemRegion delta2_left;
399 if (s2MR.start() < delta_end) {
400 delta2_left = MemRegion(s2MR.start(), delta_end);
401 s2->mangle_region(delta2_left);
402 }
403 delta_start = MAX2(s2->end(), s2MR.start());
404 MemRegion delta2_right;
405 if (delta_start < s2MR.end()) {
406 s2->mangle_region(delta2_right);
407 }
408
409 // s1
410 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
411 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
412 p2i(s1->bottom()), p2i(s1->end()),
413 p2i(s1MR.start()), p2i(s1MR.end()));
414 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
415 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
416 p2i(delta1_left.start()), p2i(delta1_left.end()),
417 p2i(delta1_right.start()), p2i(delta1_right.end()));
418
419 // s2
420 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
421 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
422 p2i(s2->bottom()), p2i(s2->end()),
423 p2i(s2MR.start()), p2i(s2MR.end()));
424 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
425 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
426 p2i(delta2_left.start()), p2i(delta2_left.end()),
427 p2i(delta2_right.start()), p2i(delta2_right.end()));
428 }
429 #endif // NOT PRODUCT
430
431 void PSYoungGen::resize_spaces(size_t requested_eden_size,
432 size_t requested_survivor_size) {
433 assert(UseAdaptiveSizePolicy, "sanity check");
434 assert(requested_eden_size > 0 && requested_survivor_size > 0,
435 "just checking");
436
437 // We require eden and to space to be empty
438 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
439 return;
440 }
441
442 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")",
443 requested_eden_size, requested_survivor_size);
444 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
445 p2i(eden_space()->bottom()),
446 p2i(eden_space()->end()),
447 pointer_delta(eden_space()->end(),
448 eden_space()->bottom(),
449 sizeof(char)));
450 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
451 p2i(from_space()->bottom()),
452 p2i(from_space()->end()),
453 pointer_delta(from_space()->end(),
454 from_space()->bottom(),
455 sizeof(char)));
456 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
457 p2i(to_space()->bottom()),
458 p2i(to_space()->end()),
459 pointer_delta( to_space()->end(),
460 to_space()->bottom(),
461 sizeof(char)));
462
463 // There's nothing to do if the new sizes are the same as the current
464 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
465 requested_survivor_size == from_space()->capacity_in_bytes() &&
466 requested_eden_size == eden_space()->capacity_in_bytes()) {
467 log_trace(gc, ergo)(" capacities are the right sizes, returning");
468 return;
469 }
470
471 char* eden_start = (char*)eden_space()->bottom();
472 char* eden_end = (char*)eden_space()->end();
473 char* from_start = (char*)from_space()->bottom();
474 char* from_end = (char*)from_space()->end();
475 char* to_start = (char*)to_space()->bottom();
476 char* to_end = (char*)to_space()->end();
477
478 const bool maintain_minimum =
479 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
480
481 bool eden_from_to_order = from_start < to_start;
482 // Check whether from space is below to space
483 if (eden_from_to_order) {
484 // Eden, from, to
485 eden_from_to_order = true;
486 log_trace(gc, ergo)(" Eden, from, to:");
487
488 // Set eden
489 // "requested_eden_size" is a goal for the size of eden
490 // and may not be attainable. "eden_size" below is
491 // calculated based on the location of from-space and
492 // the goal for the size of eden. from-space is
493 // fixed in place because it contains live data.
494 // The calculation is done this way to avoid 32bit
495 // overflow (i.e., eden_start + requested_eden_size
496 // may too large for representation in 32bits).
497 size_t eden_size;
498 if (maintain_minimum) {
499 // Only make eden larger than the requested size if
500 // the minimum size of the generation has to be maintained.
501 // This could be done in general but policy at a higher
502 // level is determining a requested size for eden and that
503 // should be honored unless there is a fundamental reason.
504 eden_size = pointer_delta(from_start,
505 eden_start,
506 sizeof(char));
507 } else {
508 eden_size = MIN2(requested_eden_size,
509 pointer_delta(from_start, eden_start, sizeof(char)));
510 }
511
512 eden_end = eden_start + eden_size;
513 assert(eden_end >= eden_start, "addition overflowed");
514
515 // To may resize into from space as long as it is clear of live data.
516 // From space must remain page aligned, though, so we need to do some
517 // extra calculations.
518
519 // First calculate an optimal to-space
520 to_end = (char*)virtual_space()->high();
521 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
522 sizeof(char));
523
524 // Does the optimal to-space overlap from-space?
525 if (to_start < (char*)from_space()->end()) {
526 // Calculate the minimum offset possible for from_end
527 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
528
529 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
530 if (from_size == 0) {
531 from_size = SpaceAlignment;
532 } else {
533 from_size = align_up(from_size, SpaceAlignment);
534 }
535
536 from_end = from_start + from_size;
537 assert(from_end > from_start, "addition overflow or from_size problem");
538
539 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
540
541 // Now update to_start with the new from_end
542 to_start = MAX2(from_end, to_start);
543 }
544
545 guarantee(to_start != to_end, "to space is zero sized");
546
547 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
548 p2i(eden_start),
549 p2i(eden_end),
550 pointer_delta(eden_end, eden_start, sizeof(char)));
551 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
552 p2i(from_start),
553 p2i(from_end),
554 pointer_delta(from_end, from_start, sizeof(char)));
555 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
556 p2i(to_start),
557 p2i(to_end),
558 pointer_delta( to_end, to_start, sizeof(char)));
559 } else {
560 // Eden, to, from
561 log_trace(gc, ergo)(" Eden, to, from:");
562
563 // To space gets priority over eden resizing. Note that we position
564 // to space as if we were able to resize from space, even though from
565 // space is not modified.
566 // Giving eden priority was tried and gave poorer performance.
567 to_end = (char*)pointer_delta(virtual_space()->high(),
568 (char*)requested_survivor_size,
569 sizeof(char));
570 to_end = MIN2(to_end, from_start);
571 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
572 sizeof(char));
573 // if the space sizes are to be increased by several times then
574 // 'to_start' will point beyond the young generation. In this case
575 // 'to_start' should be adjusted.
576 to_start = MAX2(to_start, eden_start + SpaceAlignment);
577
578 // Compute how big eden can be, then adjust end.
579 // See comments above on calculating eden_end.
580 size_t eden_size;
581 if (maintain_minimum) {
582 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
583 } else {
584 eden_size = MIN2(requested_eden_size,
585 pointer_delta(to_start, eden_start, sizeof(char)));
586 }
587 eden_end = eden_start + eden_size;
588 assert(eden_end >= eden_start, "addition overflowed");
589
590 // Could choose to not let eden shrink
591 // to_start = MAX2(to_start, eden_end);
592
593 // Don't let eden shrink down to 0 or less.
594 eden_end = MAX2(eden_end, eden_start + SpaceAlignment);
595 to_start = MAX2(to_start, eden_end);
596
597 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
598 p2i(eden_start),
599 p2i(eden_end),
600 pointer_delta(eden_end, eden_start, sizeof(char)));
601 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
602 p2i(to_start),
603 p2i(to_end),
604 pointer_delta( to_end, to_start, sizeof(char)));
605 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
606 p2i(from_start),
607 p2i(from_end),
608 pointer_delta(from_end, from_start, sizeof(char)));
609 }
610
611
612 guarantee((HeapWord*)from_start <= from_space()->bottom(),
613 "from start moved to the right");
614 guarantee((HeapWord*)from_end >= from_space()->top(),
615 "from end moved into live data");
616 assert(is_object_aligned(eden_start), "checking alignment");
617 assert(is_object_aligned(from_start), "checking alignment");
618 assert(is_object_aligned(to_start), "checking alignment");
619
620 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
621 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
622 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
623
624 // Let's make sure the call to initialize doesn't reset "top"!
625 HeapWord* old_from_top = from_space()->top();
626
627 // For logging block below
628 size_t old_from = from_space()->capacity_in_bytes();
629 size_t old_to = to_space()->capacity_in_bytes();
630
631 if (ZapUnusedHeapArea) {
632 // NUMA is a special case because a numa space is not mangled
633 // in order to not prematurely bind its address to memory to
634 // the wrong memory (i.e., don't want the GC thread to first
635 // touch the memory). The survivor spaces are not numa
636 // spaces and are mangled.
637 if (UseNUMA) {
638 if (eden_from_to_order) {
639 mangle_survivors(from_space(), fromMR, to_space(), toMR);
640 } else {
641 mangle_survivors(to_space(), toMR, from_space(), fromMR);
642 }
643 }
644
645 // If not mangling the spaces, do some checking to verify that
646 // the spaces are already mangled.
647 // The spaces should be correctly mangled at this point so
648 // do some checking here. Note that they are not being mangled
649 // in the calls to initialize().
650 // Must check mangling before the spaces are reshaped. Otherwise,
651 // the bottom or end of one space may have moved into an area
652 // covered by another space and a failure of the check may
653 // not correctly indicate which space is not properly mangled.
654 HeapWord* limit = (HeapWord*) virtual_space()->high();
655 eden_space()->check_mangled_unused_area(limit);
656 from_space()->check_mangled_unused_area(limit);
657 to_space()->check_mangled_unused_area(limit);
658 }
659 // When an existing space is being initialized, it is not
660 // mangled because the space has been previously mangled.
661 eden_space()->initialize(edenMR,
662 SpaceDecorator::Clear,
663 SpaceDecorator::DontMangle);
664 to_space()->initialize(toMR,
665 SpaceDecorator::Clear,
666 SpaceDecorator::DontMangle);
667 from_space()->initialize(fromMR,
668 SpaceDecorator::DontClear,
669 SpaceDecorator::DontMangle);
670
671 assert(from_space()->top() == old_from_top, "from top changed!");
672
673 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ",
674 ParallelScavengeHeap::heap()->total_collections(),
675 old_from, old_to,
676 from_space()->capacity_in_bytes(),
677 to_space()->capacity_in_bytes());
678 }
679
680 void PSYoungGen::swap_spaces() {
681 MutableSpace* s = from_space();
682 _from_space = to_space();
683 _to_space = s;
684
685 // Now update the decorators.
686 PSMarkSweepDecorator* md = from_mark_sweep();
687 _from_mark_sweep = to_mark_sweep();
688 _to_mark_sweep = md;
689
690 assert(from_mark_sweep()->space() == from_space(), "Sanity");
691 assert(to_mark_sweep()->space() == to_space(), "Sanity");
692 }
693
694 size_t PSYoungGen::capacity_in_bytes() const {
695 return eden_space()->capacity_in_bytes()
696 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge
697 }
698
699
700 size_t PSYoungGen::used_in_bytes() const {
701 return eden_space()->used_in_bytes()
702 + from_space()->used_in_bytes(); // to_space() is only used during scavenge
703 }
704
705
706 size_t PSYoungGen::free_in_bytes() const {
707 return eden_space()->free_in_bytes()
708 + from_space()->free_in_bytes(); // to_space() is only used during scavenge
709 }
710
711 size_t PSYoungGen::capacity_in_words() const {
712 return eden_space()->capacity_in_words()
713 + from_space()->capacity_in_words(); // to_space() is only used during scavenge
714 }
715
716
717 size_t PSYoungGen::used_in_words() const {
718 return eden_space()->used_in_words()
719 + from_space()->used_in_words(); // to_space() is only used during scavenge
720 }
721
722
723 size_t PSYoungGen::free_in_words() const {
724 return eden_space()->free_in_words()
725 + from_space()->free_in_words(); // to_space() is only used during scavenge
726 }
727
728 void PSYoungGen::object_iterate(ObjectClosure* blk) {
729 eden_space()->object_iterate(blk);
730 from_space()->object_iterate(blk);
731 to_space()->object_iterate(blk);
732 }
733
734 #if INCLUDE_SERIALGC
735
736 void PSYoungGen::precompact() {
737 eden_mark_sweep()->precompact();
738 from_mark_sweep()->precompact();
739 to_mark_sweep()->precompact();
740 }
741
742 void PSYoungGen::adjust_pointers() {
743 eden_mark_sweep()->adjust_pointers();
744 from_mark_sweep()->adjust_pointers();
745 to_mark_sweep()->adjust_pointers();
746 }
747
748 void PSYoungGen::compact() {
749 eden_mark_sweep()->compact(ZapUnusedHeapArea);
750 from_mark_sweep()->compact(ZapUnusedHeapArea);
751 // Mark sweep stores preserved markWords in to space, don't disturb!
752 to_mark_sweep()->compact(false);
753 }
754
755 #endif // INCLUDE_SERIALGC
756
757 void PSYoungGen::print() const { print_on(tty); }
758 void PSYoungGen::print_on(outputStream* st) const {
759 st->print(" %-15s", "PSYoungGen");
760 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
761 capacity_in_bytes()/K, used_in_bytes()/K);
762 virtual_space()->print_space_boundaries_on(st);
763 st->print(" eden"); eden_space()->print_on(st);
764 st->print(" from"); from_space()->print_on(st);
765 st->print(" to "); to_space()->print_on(st);
766 }
767
768 size_t PSYoungGen::available_for_expansion() {
769 ShouldNotReachHere();
770 return 0;
771 }
772
773 size_t PSYoungGen::available_for_contraction() {
774 ShouldNotReachHere();
775 return 0;
776 }
777
778 size_t PSYoungGen::available_to_min_gen() {
779 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
780 return virtual_space()->committed_size() - min_gen_size();
781 }
782
783 // This method assumes that from-space has live data and that
784 // any shrinkage of the young gen is limited by location of
785 // from-space.
786 size_t PSYoungGen::available_to_live() {
787 size_t delta_in_survivor = 0;
788 MutableSpace* space_shrinking = NULL;
789 if (from_space()->end() > to_space()->end()) {
790 space_shrinking = from_space();
791 } else {
792 space_shrinking = to_space();
793 }
794
795 // Include any space that is committed but not included in
796 // the survivor spaces.
797 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
798 "Survivor space beyond high end");
799 size_t unused_committed = pointer_delta(virtual_space()->high(),
800 space_shrinking->end(), sizeof(char));
801
802 if (space_shrinking->is_empty()) {
803 // Don't let the space shrink to 0
804 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment,
805 "Space is too small");
806 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment;
807 } else {
808 delta_in_survivor = pointer_delta(space_shrinking->end(),
809 space_shrinking->top(),
810 sizeof(char));
811 }
812
813 size_t delta_in_bytes = unused_committed + delta_in_survivor;
814 delta_in_bytes = align_down(delta_in_bytes, GenAlignment);
815 return delta_in_bytes;
816 }
817
818 // Return the number of bytes available for resizing down the young
819 // generation. This is the minimum of
820 // input "bytes"
821 // bytes to the minimum young gen size
822 // bytes to the size currently being used + some small extra
823 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
824 // Allow shrinkage into the current eden but keep eden large enough
825 // to maintain the minimum young gen size
826 bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
827 return align_down(bytes, virtual_space()->alignment());
828 }
829
830 void PSYoungGen::reset_after_change() {
831 ShouldNotReachHere();
832 }
833
834 void PSYoungGen::reset_survivors_after_shrink() {
835 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
836 (HeapWord*)virtual_space()->high_boundary());
837 PSScavenge::set_subject_to_discovery_span(_reserved);
838
839 MutableSpace* space_shrinking = NULL;
840 if (from_space()->end() > to_space()->end()) {
841 space_shrinking = from_space();
842 } else {
843 space_shrinking = to_space();
844 }
845
846 HeapWord* new_end = (HeapWord*)virtual_space()->high();
847 assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
848 // Was there a shrink of the survivor space?
849 if (new_end < space_shrinking->end()) {
850 MemRegion mr(space_shrinking->bottom(), new_end);
851 space_shrinking->initialize(mr,
852 SpaceDecorator::DontClear,
853 SpaceDecorator::Mangle);
854 }
855 }
856
857 // This method currently does not expect to expand into eden (i.e.,
858 // the virtual space boundaries is expected to be consistent
859 // with the eden boundaries..
860 void PSYoungGen::post_resize() {
861 assert_locked_or_safepoint(Heap_lock);
862 assert((eden_space()->bottom() < to_space()->bottom()) &&
863 (eden_space()->bottom() < from_space()->bottom()),
864 "Eden is assumed to be below the survivor spaces");
865
866 MemRegion cmr((HeapWord*)virtual_space()->low(),
867 (HeapWord*)virtual_space()->high());
868 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
869 space_invariants();
870 }
871
872
873
874 void PSYoungGen::update_counters() {
875 if (UsePerfData) {
876 _eden_counters->update_all();
877 _from_counters->update_all();
878 _to_counters->update_all();
879 _gen_counters->update_all();
880 }
881 }
882
883 void PSYoungGen::verify() {
884 eden_space()->verify();
885 from_space()->verify();
886 to_space()->verify();
887 }
888
889 #ifndef PRODUCT
890 void PSYoungGen::record_spaces_top() {
891 assert(ZapUnusedHeapArea, "Not mangling unused space");
892 eden_space()->set_top_for_allocations();
893 from_space()->set_top_for_allocations();
894 to_space()->set_top_for_allocations();
895 }
896 #endif