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