1 /*
2 * Copyright (c) 2001, 2020, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "gc/parallel/mutableNUMASpace.hpp"
27 #include "gc/parallel/parallelScavengeHeap.hpp"
28 #include "gc/parallel/psScavenge.hpp"
29 #include "gc/parallel/psYoungGen.hpp"
30 #include "gc/shared/gcUtil.hpp"
31 #include "gc/shared/genArguments.hpp"
32 #include "gc/shared/spaceDecorator.inline.hpp"
33 #include "logging/log.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/java.hpp"
36 #include "utilities/align.hpp"
37
38 PSYoungGen::PSYoungGen(ReservedSpace rs, size_t initial_size, size_t min_size, size_t max_size) :
39 _reserved(),
40 _virtual_space(NULL),
41 _eden_space(NULL),
42 _from_space(NULL),
43 _to_space(NULL),
44 _min_gen_size(min_size),
45 _max_gen_size(max_size),
46 _gen_counters(NULL),
47 _eden_counters(NULL),
48 _from_counters(NULL),
49 _to_counters(NULL)
50 {
51 initialize(rs, initial_size, GenAlignment);
52 }
53
54 void PSYoungGen::initialize_virtual_space(ReservedSpace rs,
55 size_t initial_size,
56 size_t alignment) {
57 assert(initial_size != 0, "Should have a finite size");
58 _virtual_space = new PSVirtualSpace(rs, alignment);
59 if (!virtual_space()->expand_by(initial_size)) {
60 vm_exit_during_initialization("Could not reserve enough space for object heap");
61 }
62 }
63
64 void PSYoungGen::initialize(ReservedSpace rs, size_t initial_size, size_t alignment) {
65 initialize_virtual_space(rs, initial_size, alignment);
66 initialize_work();
67 }
68
69 void PSYoungGen::initialize_work() {
70
71 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
72 (HeapWord*)virtual_space()->high_boundary());
73 assert(_reserved.byte_size() == max_gen_size(), "invariant");
74
75 MemRegion cmr((HeapWord*)virtual_space()->low(),
76 (HeapWord*)virtual_space()->high());
77 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
78
79 if (ZapUnusedHeapArea) {
80 // Mangle newly committed space immediately because it
81 // can be done here more simply that after the new
82 // spaces have been computed.
83 SpaceMangler::mangle_region(cmr);
84 }
85
86 if (UseNUMA) {
87 _eden_space = new MutableNUMASpace(virtual_space()->alignment());
88 } else {
89 _eden_space = new MutableSpace(virtual_space()->alignment());
90 }
91 _from_space = new MutableSpace(virtual_space()->alignment());
92 _to_space = new MutableSpace(virtual_space()->alignment());
93
94 // Generation Counters - generation 0, 3 subspaces
95 _gen_counters = new PSGenerationCounters("new", 0, 3, min_gen_size(),
96 max_gen_size(), virtual_space());
97
98 // Compute maximum space sizes for performance counters
99 size_t alignment = SpaceAlignment;
100 size_t size = virtual_space()->reserved_size();
101
102 size_t max_survivor_size;
103 size_t max_eden_size;
104
105 if (UseAdaptiveSizePolicy) {
106 max_survivor_size = size / MinSurvivorRatio;
107
108 // round the survivor space size down to the nearest alignment
109 // and make sure its size is greater than 0.
110 max_survivor_size = align_down(max_survivor_size, alignment);
111 max_survivor_size = MAX2(max_survivor_size, alignment);
112
113 // set the maximum size of eden to be the size of the young gen
114 // less two times the minimum survivor size. The minimum survivor
115 // size for UseAdaptiveSizePolicy is one alignment.
116 max_eden_size = size - 2 * alignment;
117 } else {
118 max_survivor_size = size / InitialSurvivorRatio;
119
120 // round the survivor space size down to the nearest alignment
121 // and make sure its size is greater than 0.
122 max_survivor_size = align_down(max_survivor_size, alignment);
123 max_survivor_size = MAX2(max_survivor_size, alignment);
124
125 // set the maximum size of eden to be the size of the young gen
126 // less two times the survivor size when the generation is 100%
127 // committed. The minimum survivor size for -UseAdaptiveSizePolicy
128 // is dependent on the committed portion (current capacity) of the
129 // generation - the less space committed, the smaller the survivor
130 // space, possibly as small as an alignment. However, we are interested
131 // in the case where the young generation is 100% committed, as this
132 // is the point where eden reaches its maximum size. At this point,
133 // the size of a survivor space is max_survivor_size.
134 max_eden_size = size - 2 * max_survivor_size;
135 }
136
137 _eden_counters = new SpaceCounters("eden", 0, max_eden_size, _eden_space,
138 _gen_counters);
139 _from_counters = new SpaceCounters("s0", 1, max_survivor_size, _from_space,
140 _gen_counters);
141 _to_counters = new SpaceCounters("s1", 2, max_survivor_size, _to_space,
142 _gen_counters);
143
144 compute_initial_space_boundaries();
145 }
146
147 void PSYoungGen::compute_initial_space_boundaries() {
148 // Compute sizes
149 size_t size = virtual_space()->committed_size();
150 assert(size >= 3 * SpaceAlignment, "Young space is not large enough for eden + 2 survivors");
151
152 size_t survivor_size = size / InitialSurvivorRatio;
153 survivor_size = align_down(survivor_size, SpaceAlignment);
154 // ... but never less than an alignment
155 survivor_size = MAX2(survivor_size, SpaceAlignment);
156
157 // Young generation is eden + 2 survivor spaces
158 size_t eden_size = size - (2 * survivor_size);
159
160 // Now go ahead and set 'em.
161 set_space_boundaries(eden_size, survivor_size);
162 space_invariants();
163
164 if (UsePerfData) {
165 _eden_counters->update_capacity();
166 _from_counters->update_capacity();
167 _to_counters->update_capacity();
168 }
169 }
170
171 void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) {
172 assert(eden_size < virtual_space()->committed_size(), "just checking");
173 assert(eden_size > 0 && survivor_size > 0, "just checking");
174
175 // Initial layout is Eden, to, from. After swapping survivor spaces,
176 // that leaves us with Eden, from, to, which is step one in our two
177 // step resize-with-live-data procedure.
178 char *eden_start = virtual_space()->low();
179 char *to_start = eden_start + eden_size;
180 char *from_start = to_start + survivor_size;
181 char *from_end = from_start + survivor_size;
182
183 assert(from_end == virtual_space()->high(), "just checking");
184 assert(is_object_aligned(eden_start), "checking alignment");
185 assert(is_object_aligned(to_start), "checking alignment");
186 assert(is_object_aligned(from_start), "checking alignment");
187
188 MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start);
189 MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start);
190 MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end);
191
192 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea);
193 to_space()->initialize(to_mr , true, ZapUnusedHeapArea);
194 from_space()->initialize(from_mr, true, ZapUnusedHeapArea);
195 }
196
197 #ifndef PRODUCT
198 void PSYoungGen::space_invariants() {
199 // Currently, our eden size cannot shrink to zero
200 guarantee(eden_space()->capacity_in_bytes() >= SpaceAlignment, "eden too small");
201 guarantee(from_space()->capacity_in_bytes() >= SpaceAlignment, "from too small");
202 guarantee(to_space()->capacity_in_bytes() >= SpaceAlignment, "to too small");
203
204 // Relationship of spaces to each other
205 char* eden_start = (char*)eden_space()->bottom();
206 char* eden_end = (char*)eden_space()->end();
207 char* from_start = (char*)from_space()->bottom();
208 char* from_end = (char*)from_space()->end();
209 char* to_start = (char*)to_space()->bottom();
210 char* to_end = (char*)to_space()->end();
211
212 guarantee(eden_start >= virtual_space()->low(), "eden bottom");
213 guarantee(eden_start < eden_end, "eden space consistency");
214 guarantee(from_start < from_end, "from space consistency");
215 guarantee(to_start < to_end, "to space consistency");
216
217 // Check whether from space is below to space
218 if (from_start < to_start) {
219 // Eden, from, to
220 guarantee(eden_end <= from_start, "eden/from boundary");
221 guarantee(from_end <= to_start, "from/to boundary");
222 guarantee(to_end <= virtual_space()->high(), "to end");
223 } else {
224 // Eden, to, from
225 guarantee(eden_end <= to_start, "eden/to boundary");
226 guarantee(to_end <= from_start, "to/from boundary");
227 guarantee(from_end <= virtual_space()->high(), "from end");
228 }
229
230 // More checks that the virtual space is consistent with the spaces
231 assert(virtual_space()->committed_size() >=
232 (eden_space()->capacity_in_bytes() +
233 to_space()->capacity_in_bytes() +
234 from_space()->capacity_in_bytes()), "Committed size is inconsistent");
235 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
236 "Space invariant");
237 char* eden_top = (char*)eden_space()->top();
238 char* from_top = (char*)from_space()->top();
239 char* to_top = (char*)to_space()->top();
240 assert(eden_top <= virtual_space()->high(), "eden top");
241 assert(from_top <= virtual_space()->high(), "from top");
242 assert(to_top <= virtual_space()->high(), "to top");
243
244 virtual_space()->verify();
245 }
246 #endif
247
248 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) {
249 // Resize the generation if needed. If the generation resize
250 // reports false, do not attempt to resize the spaces.
251 if (resize_generation(eden_size, survivor_size)) {
252 // Then we lay out the spaces inside the generation
253 resize_spaces(eden_size, survivor_size);
254
255 space_invariants();
256
257 log_trace(gc, ergo)("Young generation size: "
258 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
259 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
260 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
261 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(),
262 max_gen_size(), min_gen_size());
263 }
264 }
265
266
267 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
268 const size_t alignment = virtual_space()->alignment();
269 size_t orig_size = virtual_space()->committed_size();
270 bool size_changed = false;
271
272 // There used to be this guarantee there.
273 // guarantee ((eden_size + 2*survivor_size) <= max_gen_size(), "incorrect input arguments");
274 // Code below forces this requirement. In addition the desired eden
275 // size and desired survivor sizes are desired goals and may
276 // exceed the total generation size.
277
278 assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(), "just checking");
279
280 // Adjust new generation size
281 const size_t eden_plus_survivors =
282 align_up(eden_size + 2 * survivor_size, alignment);
283 size_t desired_size = clamp(eden_plus_survivors, min_gen_size(), max_gen_size());
284 assert(desired_size <= max_gen_size(), "just checking");
285
286 if (desired_size > orig_size) {
287 // Grow the generation
288 size_t change = desired_size - orig_size;
289 assert(change % alignment == 0, "just checking");
290 HeapWord* prev_high = (HeapWord*) virtual_space()->high();
291 if (!virtual_space()->expand_by(change)) {
292 return false; // Error if we fail to resize!
293 }
294 if (ZapUnusedHeapArea) {
295 // Mangle newly committed space immediately because it
296 // can be done here more simply that after the new
297 // spaces have been computed.
298 HeapWord* new_high = (HeapWord*) virtual_space()->high();
299 MemRegion mangle_region(prev_high, new_high);
300 SpaceMangler::mangle_region(mangle_region);
301 }
302 size_changed = true;
303 } else if (desired_size < orig_size) {
304 size_t desired_change = orig_size - desired_size;
305 assert(desired_change % alignment == 0, "just checking");
306
307 desired_change = limit_gen_shrink(desired_change);
308
309 if (desired_change > 0) {
310 virtual_space()->shrink_by(desired_change);
311 reset_survivors_after_shrink();
312
313 size_changed = true;
314 }
315 } else {
316 if (orig_size == max_gen_size()) {
317 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
318 } else if (orig_size == min_gen_size()) {
319 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
320 }
321 }
322
323 if (size_changed) {
324 post_resize();
325 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
326 orig_size/K, virtual_space()->committed_size()/K);
327 }
328
329 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
330 virtual_space()->committed_size() == max_gen_size(), "Sanity");
331
332 return true;
333 }
334
335 #ifndef PRODUCT
336 // In the numa case eden is not mangled so a survivor space
337 // moving into a region previously occupied by a survivor
338 // may find an unmangled region. Also in the PS case eden
339 // to-space and from-space may not touch (i.e., there may be
340 // gaps between them due to movement while resizing the
341 // spaces). Those gaps must be mangled.
342 void PSYoungGen::mangle_survivors(MutableSpace* s1,
343 MemRegion s1MR,
344 MutableSpace* s2,
345 MemRegion s2MR) {
346 // Check eden and gap between eden and from-space, in deciding
347 // what to mangle in from-space. Check the gap between from-space
348 // and to-space when deciding what to mangle.
349 //
350 // +--------+ +----+ +---+
351 // | eden | |s1 | |s2 |
352 // +--------+ +----+ +---+
353 // +-------+ +-----+
354 // |s1MR | |s2MR |
355 // +-------+ +-----+
356 // All of survivor-space is properly mangled so find the
357 // upper bound on the mangling for any portion above current s1.
358 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end());
359 MemRegion delta1_left;
360 if (s1MR.start() < delta_end) {
361 delta1_left = MemRegion(s1MR.start(), delta_end);
362 s1->mangle_region(delta1_left);
363 }
364 // Find any portion to the right of the current s1.
365 HeapWord* delta_start = MAX2(s1->end(), s1MR.start());
366 MemRegion delta1_right;
367 if (delta_start < s1MR.end()) {
368 delta1_right = MemRegion(delta_start, s1MR.end());
369 s1->mangle_region(delta1_right);
370 }
371
372 // Similarly for the second survivor space except that
373 // any of the new region that overlaps with the current
374 // region of the first survivor space has already been
375 // mangled.
376 delta_end = MIN2(s2->bottom(), s2MR.end());
377 delta_start = MAX2(s2MR.start(), s1->end());
378 MemRegion delta2_left;
379 if (s2MR.start() < delta_end) {
380 delta2_left = MemRegion(s2MR.start(), delta_end);
381 s2->mangle_region(delta2_left);
382 }
383 delta_start = MAX2(s2->end(), s2MR.start());
384 MemRegion delta2_right;
385 if (delta_start < s2MR.end()) {
386 s2->mangle_region(delta2_right);
387 }
388
389 // s1
390 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
391 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
392 p2i(s1->bottom()), p2i(s1->end()),
393 p2i(s1MR.start()), p2i(s1MR.end()));
394 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
395 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
396 p2i(delta1_left.start()), p2i(delta1_left.end()),
397 p2i(delta1_right.start()), p2i(delta1_right.end()));
398
399 // s2
400 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
401 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
402 p2i(s2->bottom()), p2i(s2->end()),
403 p2i(s2MR.start()), p2i(s2MR.end()));
404 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
405 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
406 p2i(delta2_left.start()), p2i(delta2_left.end()),
407 p2i(delta2_right.start()), p2i(delta2_right.end()));
408 }
409 #endif // NOT PRODUCT
410
411 void PSYoungGen::resize_spaces(size_t requested_eden_size,
412 size_t requested_survivor_size) {
413 assert(UseAdaptiveSizePolicy, "sanity check");
414 assert(requested_eden_size > 0 && requested_survivor_size > 0,
415 "just checking");
416
417 // We require eden and to space to be empty
418 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
419 return;
420 }
421
422 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")",
423 requested_eden_size, requested_survivor_size);
424 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
425 p2i(eden_space()->bottom()),
426 p2i(eden_space()->end()),
427 pointer_delta(eden_space()->end(),
428 eden_space()->bottom(),
429 sizeof(char)));
430 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
431 p2i(from_space()->bottom()),
432 p2i(from_space()->end()),
433 pointer_delta(from_space()->end(),
434 from_space()->bottom(),
435 sizeof(char)));
436 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
437 p2i(to_space()->bottom()),
438 p2i(to_space()->end()),
439 pointer_delta( to_space()->end(),
440 to_space()->bottom(),
441 sizeof(char)));
442
443 // There's nothing to do if the new sizes are the same as the current
444 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
445 requested_survivor_size == from_space()->capacity_in_bytes() &&
446 requested_eden_size == eden_space()->capacity_in_bytes()) {
447 log_trace(gc, ergo)(" capacities are the right sizes, returning");
448 return;
449 }
450
451 char* eden_start = (char*)eden_space()->bottom();
452 char* eden_end = (char*)eden_space()->end();
453 char* from_start = (char*)from_space()->bottom();
454 char* from_end = (char*)from_space()->end();
455 char* to_start = (char*)to_space()->bottom();
456 char* to_end = (char*)to_space()->end();
457
458 const bool maintain_minimum =
459 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
460
461 bool eden_from_to_order = from_start < to_start;
462 // Check whether from space is below to space
463 if (eden_from_to_order) {
464 // Eden, from, to
465 eden_from_to_order = true;
466 log_trace(gc, ergo)(" Eden, from, to:");
467
468 // Set eden
469 // "requested_eden_size" is a goal for the size of eden
470 // and may not be attainable. "eden_size" below is
471 // calculated based on the location of from-space and
472 // the goal for the size of eden. from-space is
473 // fixed in place because it contains live data.
474 // The calculation is done this way to avoid 32bit
475 // overflow (i.e., eden_start + requested_eden_size
476 // may too large for representation in 32bits).
477 size_t eden_size;
478 if (maintain_minimum) {
479 // Only make eden larger than the requested size if
480 // the minimum size of the generation has to be maintained.
481 // This could be done in general but policy at a higher
482 // level is determining a requested size for eden and that
483 // should be honored unless there is a fundamental reason.
484 eden_size = pointer_delta(from_start,
485 eden_start,
486 sizeof(char));
487 } else {
488 eden_size = MIN2(requested_eden_size,
489 pointer_delta(from_start, eden_start, sizeof(char)));
490 }
491
492 eden_end = eden_start + eden_size;
493 assert(eden_end >= eden_start, "addition overflowed");
494
495 // To may resize into from space as long as it is clear of live data.
496 // From space must remain page aligned, though, so we need to do some
497 // extra calculations.
498
499 // First calculate an optimal to-space
500 to_end = (char*)virtual_space()->high();
501 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
502 sizeof(char));
503
504 // Does the optimal to-space overlap from-space?
505 if (to_start < (char*)from_space()->end()) {
506 // Calculate the minimum offset possible for from_end
507 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
508
509 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
510 if (from_size == 0) {
511 from_size = SpaceAlignment;
512 } else {
513 from_size = align_up(from_size, SpaceAlignment);
514 }
515
516 from_end = from_start + from_size;
517 assert(from_end > from_start, "addition overflow or from_size problem");
518
519 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
520
521 // Now update to_start with the new from_end
522 to_start = MAX2(from_end, to_start);
523 }
524
525 guarantee(to_start != to_end, "to space is zero sized");
526
527 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
528 p2i(eden_start),
529 p2i(eden_end),
530 pointer_delta(eden_end, eden_start, sizeof(char)));
531 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
532 p2i(from_start),
533 p2i(from_end),
534 pointer_delta(from_end, from_start, sizeof(char)));
535 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
536 p2i(to_start),
537 p2i(to_end),
538 pointer_delta( to_end, to_start, sizeof(char)));
539 } else {
540 // Eden, to, from
541 log_trace(gc, ergo)(" Eden, to, from:");
542
543 // To space gets priority over eden resizing. Note that we position
544 // to space as if we were able to resize from space, even though from
545 // space is not modified.
546 // Giving eden priority was tried and gave poorer performance.
547 to_end = (char*)pointer_delta(virtual_space()->high(),
548 (char*)requested_survivor_size,
549 sizeof(char));
550 to_end = MIN2(to_end, from_start);
551 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
552 sizeof(char));
553 // if the space sizes are to be increased by several times then
554 // 'to_start' will point beyond the young generation. In this case
555 // 'to_start' should be adjusted.
556 to_start = MAX2(to_start, eden_start + SpaceAlignment);
557
558 // Compute how big eden can be, then adjust end.
559 // See comments above on calculating eden_end.
560 size_t eden_size;
561 if (maintain_minimum) {
562 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
563 } else {
564 eden_size = MIN2(requested_eden_size,
565 pointer_delta(to_start, eden_start, sizeof(char)));
566 }
567 eden_end = eden_start + eden_size;
568 assert(eden_end >= eden_start, "addition overflowed");
569
570 // Could choose to not let eden shrink
571 // to_start = MAX2(to_start, eden_end);
572
573 // Don't let eden shrink down to 0 or less.
574 eden_end = MAX2(eden_end, eden_start + SpaceAlignment);
575 to_start = MAX2(to_start, eden_end);
576
577 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
578 p2i(eden_start),
579 p2i(eden_end),
580 pointer_delta(eden_end, eden_start, sizeof(char)));
581 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
582 p2i(to_start),
583 p2i(to_end),
584 pointer_delta( to_end, to_start, sizeof(char)));
585 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
586 p2i(from_start),
587 p2i(from_end),
588 pointer_delta(from_end, from_start, sizeof(char)));
589 }
590
591
592 guarantee((HeapWord*)from_start <= from_space()->bottom(),
593 "from start moved to the right");
594 guarantee((HeapWord*)from_end >= from_space()->top(),
595 "from end moved into live data");
596 assert(is_object_aligned(eden_start), "checking alignment");
597 assert(is_object_aligned(from_start), "checking alignment");
598 assert(is_object_aligned(to_start), "checking alignment");
599
600 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
601 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
602 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
603
604 // Let's make sure the call to initialize doesn't reset "top"!
605 HeapWord* old_from_top = from_space()->top();
606
607 // For logging block below
608 size_t old_from = from_space()->capacity_in_bytes();
609 size_t old_to = to_space()->capacity_in_bytes();
610
611 if (ZapUnusedHeapArea) {
612 // NUMA is a special case because a numa space is not mangled
613 // in order to not prematurely bind its address to memory to
614 // the wrong memory (i.e., don't want the GC thread to first
615 // touch the memory). The survivor spaces are not numa
616 // spaces and are mangled.
617 if (UseNUMA) {
618 if (eden_from_to_order) {
619 mangle_survivors(from_space(), fromMR, to_space(), toMR);
620 } else {
621 mangle_survivors(to_space(), toMR, from_space(), fromMR);
622 }
623 }
624
625 // If not mangling the spaces, do some checking to verify that
626 // the spaces are already mangled.
627 // The spaces should be correctly mangled at this point so
628 // do some checking here. Note that they are not being mangled
629 // in the calls to initialize().
630 // Must check mangling before the spaces are reshaped. Otherwise,
631 // the bottom or end of one space may have moved into an area
632 // covered by another space and a failure of the check may
633 // not correctly indicate which space is not properly mangled.
634 HeapWord* limit = (HeapWord*) virtual_space()->high();
635 eden_space()->check_mangled_unused_area(limit);
636 from_space()->check_mangled_unused_area(limit);
637 to_space()->check_mangled_unused_area(limit);
638 }
639 // When an existing space is being initialized, it is not
640 // mangled because the space has been previously mangled.
641 eden_space()->initialize(edenMR,
642 SpaceDecorator::Clear,
643 SpaceDecorator::DontMangle);
644 to_space()->initialize(toMR,
645 SpaceDecorator::Clear,
646 SpaceDecorator::DontMangle);
647 from_space()->initialize(fromMR,
648 SpaceDecorator::DontClear,
649 SpaceDecorator::DontMangle);
650
651 assert(from_space()->top() == old_from_top, "from top changed!");
652
653 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ",
654 ParallelScavengeHeap::heap()->total_collections(),
655 old_from, old_to,
656 from_space()->capacity_in_bytes(),
657 to_space()->capacity_in_bytes());
658 }
659
660 void PSYoungGen::swap_spaces() {
661 MutableSpace* s = from_space();
662 _from_space = to_space();
663 _to_space = s;
664 }
665
666 size_t PSYoungGen::capacity_in_bytes() const {
667 return eden_space()->capacity_in_bytes()
668 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge
669 }
670
671
672 size_t PSYoungGen::used_in_bytes() const {
673 return eden_space()->used_in_bytes()
674 + from_space()->used_in_bytes(); // to_space() is only used during scavenge
675 }
676
677
678 size_t PSYoungGen::free_in_bytes() const {
679 return eden_space()->free_in_bytes()
680 + from_space()->free_in_bytes(); // to_space() is only used during scavenge
681 }
682
683 size_t PSYoungGen::capacity_in_words() const {
684 return eden_space()->capacity_in_words()
685 + from_space()->capacity_in_words(); // to_space() is only used during scavenge
686 }
687
688
689 size_t PSYoungGen::used_in_words() const {
690 return eden_space()->used_in_words()
691 + from_space()->used_in_words(); // to_space() is only used during scavenge
692 }
693
694
695 size_t PSYoungGen::free_in_words() const {
696 return eden_space()->free_in_words()
697 + from_space()->free_in_words(); // to_space() is only used during scavenge
698 }
699
700 void PSYoungGen::object_iterate(ObjectClosure* blk) {
701 eden_space()->object_iterate(blk);
702 from_space()->object_iterate(blk);
703 to_space()->object_iterate(blk);
704 }
705
706 void PSYoungGen::print() const { print_on(tty); }
707 void PSYoungGen::print_on(outputStream* st) const {
708 st->print(" %-15s", "PSYoungGen");
709 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
710 capacity_in_bytes()/K, used_in_bytes()/K);
711 virtual_space()->print_space_boundaries_on(st);
712 st->print(" eden"); eden_space()->print_on(st);
713 st->print(" from"); from_space()->print_on(st);
714 st->print(" to "); to_space()->print_on(st);
715 }
716
717 size_t PSYoungGen::available_to_min_gen() {
718 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
719 return virtual_space()->committed_size() - min_gen_size();
720 }
721
722 // This method assumes that from-space has live data and that
723 // any shrinkage of the young gen is limited by location of
724 // from-space.
725 size_t PSYoungGen::available_to_live() {
726 size_t delta_in_survivor = 0;
727 MutableSpace* space_shrinking = NULL;
728 if (from_space()->end() > to_space()->end()) {
729 space_shrinking = from_space();
730 } else {
731 space_shrinking = to_space();
732 }
733
734 // Include any space that is committed but not included in
735 // the survivor spaces.
736 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
737 "Survivor space beyond high end");
738 size_t unused_committed = pointer_delta(virtual_space()->high(),
739 space_shrinking->end(), sizeof(char));
740
741 if (space_shrinking->is_empty()) {
742 // Don't let the space shrink to 0
743 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment,
744 "Space is too small");
745 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment;
746 } else {
747 delta_in_survivor = pointer_delta(space_shrinking->end(),
748 space_shrinking->top(),
749 sizeof(char));
750 }
751
752 size_t delta_in_bytes = unused_committed + delta_in_survivor;
753 delta_in_bytes = align_down(delta_in_bytes, GenAlignment);
754 return delta_in_bytes;
755 }
756
757 // Return the number of bytes available for resizing down the young
758 // generation. This is the minimum of
759 // input "bytes"
760 // bytes to the minimum young gen size
761 // bytes to the size currently being used + some small extra
762 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
763 // Allow shrinkage into the current eden but keep eden large enough
764 // to maintain the minimum young gen size
765 bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
766 return align_down(bytes, virtual_space()->alignment());
767 }
768
769 void PSYoungGen::reset_survivors_after_shrink() {
770 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
771 (HeapWord*)virtual_space()->high_boundary());
772 PSScavenge::set_subject_to_discovery_span(_reserved);
773
774 MutableSpace* space_shrinking = NULL;
775 if (from_space()->end() > to_space()->end()) {
776 space_shrinking = from_space();
777 } else {
778 space_shrinking = to_space();
779 }
780
781 HeapWord* new_end = (HeapWord*)virtual_space()->high();
782 assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
783 // Was there a shrink of the survivor space?
784 if (new_end < space_shrinking->end()) {
785 MemRegion mr(space_shrinking->bottom(), new_end);
786 space_shrinking->initialize(mr,
787 SpaceDecorator::DontClear,
788 SpaceDecorator::Mangle);
789 }
790 }
791
792 // This method currently does not expect to expand into eden (i.e.,
793 // the virtual space boundaries is expected to be consistent
794 // with the eden boundaries..
795 void PSYoungGen::post_resize() {
796 assert_locked_or_safepoint(Heap_lock);
797 assert((eden_space()->bottom() < to_space()->bottom()) &&
798 (eden_space()->bottom() < from_space()->bottom()),
799 "Eden is assumed to be below the survivor spaces");
800
801 MemRegion cmr((HeapWord*)virtual_space()->low(),
802 (HeapWord*)virtual_space()->high());
803 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
804 space_invariants();
805 }
806
807
808
809 void PSYoungGen::update_counters() {
810 if (UsePerfData) {
811 _eden_counters->update_all();
812 _from_counters->update_all();
813 _to_counters->update_all();
814 _gen_counters->update_all();
815 }
816 }
817
818 void PSYoungGen::verify() {
819 eden_space()->verify();
820 from_space()->verify();
821 to_space()->verify();
822 }
823
824 #ifndef PRODUCT
825 void PSYoungGen::record_spaces_top() {
826 assert(ZapUnusedHeapArea, "Not mangling unused space");
827 eden_space()->set_top_for_allocations();
828 from_space()->set_top_for_allocations();
829 to_space()->set_top_for_allocations();
830 }
831 #endif