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.
22 *
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 WorkGang& pretouch_workers = ParallelScavengeHeap::heap()->workers();
193 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea, MutableSpace::SetupPages, &pretouch_workers);
194 to_space()->initialize(to_mr , true, ZapUnusedHeapArea, MutableSpace::SetupPages, &pretouch_workers);
195 from_space()->initialize(from_mr, true, ZapUnusedHeapArea, MutableSpace::SetupPages, &pretouch_workers);
196 }
197
198 #ifndef PRODUCT
199 void PSYoungGen::space_invariants() {
200 // Currently, our eden size cannot shrink to zero
201 guarantee(eden_space()->capacity_in_bytes() >= SpaceAlignment, "eden too small");
202 guarantee(from_space()->capacity_in_bytes() >= SpaceAlignment, "from too small");
203 guarantee(to_space()->capacity_in_bytes() >= SpaceAlignment, "to too small");
204
205 // Relationship of spaces to each other
206 char* eden_start = (char*)eden_space()->bottom();
207 char* eden_end = (char*)eden_space()->end();
208 char* from_start = (char*)from_space()->bottom();
209 char* from_end = (char*)from_space()->end();
210 char* to_start = (char*)to_space()->bottom();
211 char* to_end = (char*)to_space()->end();
212
213 guarantee(eden_start >= virtual_space()->low(), "eden bottom");
214 guarantee(eden_start < eden_end, "eden space consistency");
215 guarantee(from_start < from_end, "from space consistency");
216 guarantee(to_start < to_end, "to space consistency");
217
218 // Check whether from space is below to space
219 if (from_start < to_start) {
220 // Eden, from, to
221 guarantee(eden_end <= from_start, "eden/from boundary");
222 guarantee(from_end <= to_start, "from/to boundary");
223 guarantee(to_end <= virtual_space()->high(), "to end");
224 } else {
225 // Eden, to, from
226 guarantee(eden_end <= to_start, "eden/to boundary");
227 guarantee(to_end <= from_start, "to/from boundary");
228 guarantee(from_end <= virtual_space()->high(), "from end");
229 }
230
231 // More checks that the virtual space is consistent with the spaces
232 assert(virtual_space()->committed_size() >=
233 (eden_space()->capacity_in_bytes() +
234 to_space()->capacity_in_bytes() +
235 from_space()->capacity_in_bytes()), "Committed size is inconsistent");
236 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
237 "Space invariant");
238 char* eden_top = (char*)eden_space()->top();
239 char* from_top = (char*)from_space()->top();
240 char* to_top = (char*)to_space()->top();
241 assert(eden_top <= virtual_space()->high(), "eden top");
242 assert(from_top <= virtual_space()->high(), "from top");
243 assert(to_top <= virtual_space()->high(), "to top");
244
245 virtual_space()->verify();
246 }
247 #endif
248
249 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) {
250 // Resize the generation if needed. If the generation resize
251 // reports false, do not attempt to resize the spaces.
252 if (resize_generation(eden_size, survivor_size)) {
253 // Then we lay out the spaces inside the generation
254 resize_spaces(eden_size, survivor_size);
255
256 space_invariants();
257
258 log_trace(gc, ergo)("Young generation size: "
259 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
260 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
261 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
262 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(),
263 max_gen_size(), min_gen_size());
264 }
265 }
266
267
268 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
269 const size_t alignment = virtual_space()->alignment();
270 size_t orig_size = virtual_space()->committed_size();
271 bool size_changed = false;
272
273 // There used to be this guarantee there.
274 // guarantee ((eden_size + 2*survivor_size) <= max_gen_size(), "incorrect input arguments");
275 // Code below forces this requirement. In addition the desired eden
276 // size and desired survivor sizes are desired goals and may
277 // exceed the total generation size.
278
279 assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(), "just checking");
280
281 // Adjust new generation size
282 const size_t eden_plus_survivors =
283 align_up(eden_size + 2 * survivor_size, alignment);
284 size_t desired_size = clamp(eden_plus_survivors, min_gen_size(), max_gen_size());
285 assert(desired_size <= max_gen_size(), "just checking");
286
287 if (desired_size > orig_size) {
288 // Grow the generation
289 size_t change = desired_size - orig_size;
290 assert(change % alignment == 0, "just checking");
291 HeapWord* prev_high = (HeapWord*) virtual_space()->high();
292 if (!virtual_space()->expand_by(change)) {
293 return false; // Error if we fail to resize!
294 }
295 if (ZapUnusedHeapArea) {
296 // Mangle newly committed space immediately because it
297 // can be done here more simply that after the new
298 // spaces have been computed.
299 HeapWord* new_high = (HeapWord*) virtual_space()->high();
300 MemRegion mangle_region(prev_high, new_high);
301 SpaceMangler::mangle_region(mangle_region);
302 }
303 size_changed = true;
304 } else if (desired_size < orig_size) {
305 size_t desired_change = orig_size - desired_size;
306 assert(desired_change % alignment == 0, "just checking");
307
308 desired_change = limit_gen_shrink(desired_change);
309
310 if (desired_change > 0) {
311 virtual_space()->shrink_by(desired_change);
312 reset_survivors_after_shrink();
313
314 size_changed = true;
315 }
316 } else {
317 if (orig_size == max_gen_size()) {
318 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
319 } else if (orig_size == min_gen_size()) {
320 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
321 }
322 }
323
324 if (size_changed) {
325 post_resize();
326 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
327 orig_size/K, virtual_space()->committed_size()/K);
328 }
329
330 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
331 virtual_space()->committed_size() == max_gen_size(), "Sanity");
332
333 return true;
334 }
335
336 #ifndef PRODUCT
337 // In the numa case eden is not mangled so a survivor space
338 // moving into a region previously occupied by a survivor
339 // may find an unmangled region. Also in the PS case eden
340 // to-space and from-space may not touch (i.e., there may be
341 // gaps between them due to movement while resizing the
342 // spaces). Those gaps must be mangled.
343 void PSYoungGen::mangle_survivors(MutableSpace* s1,
344 MemRegion s1MR,
345 MutableSpace* s2,
346 MemRegion s2MR) {
347 // Check eden and gap between eden and from-space, in deciding
348 // what to mangle in from-space. Check the gap between from-space
349 // and to-space when deciding what to mangle.
350 //
351 // +--------+ +----+ +---+
352 // | eden | |s1 | |s2 |
353 // +--------+ +----+ +---+
354 // +-------+ +-----+
355 // |s1MR | |s2MR |
356 // +-------+ +-----+
357 // All of survivor-space is properly mangled so find the
358 // upper bound on the mangling for any portion above current s1.
359 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end());
360 MemRegion delta1_left;
361 if (s1MR.start() < delta_end) {
362 delta1_left = MemRegion(s1MR.start(), delta_end);
363 s1->mangle_region(delta1_left);
364 }
365 // Find any portion to the right of the current s1.
366 HeapWord* delta_start = MAX2(s1->end(), s1MR.start());
367 MemRegion delta1_right;
368 if (delta_start < s1MR.end()) {
369 delta1_right = MemRegion(delta_start, s1MR.end());
370 s1->mangle_region(delta1_right);
371 }
372
373 // Similarly for the second survivor space except that
374 // any of the new region that overlaps with the current
375 // region of the first survivor space has already been
376 // mangled.
377 delta_end = MIN2(s2->bottom(), s2MR.end());
378 delta_start = MAX2(s2MR.start(), s1->end());
379 MemRegion delta2_left;
380 if (s2MR.start() < delta_end) {
381 delta2_left = MemRegion(s2MR.start(), delta_end);
382 s2->mangle_region(delta2_left);
383 }
384 delta_start = MAX2(s2->end(), s2MR.start());
385 MemRegion delta2_right;
386 if (delta_start < s2MR.end()) {
387 s2->mangle_region(delta2_right);
388 }
389
390 // s1
391 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
392 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
393 p2i(s1->bottom()), p2i(s1->end()),
394 p2i(s1MR.start()), p2i(s1MR.end()));
395 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
396 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
397 p2i(delta1_left.start()), p2i(delta1_left.end()),
398 p2i(delta1_right.start()), p2i(delta1_right.end()));
399
400 // s2
401 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
402 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
403 p2i(s2->bottom()), p2i(s2->end()),
404 p2i(s2MR.start()), p2i(s2MR.end()));
405 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
406 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
407 p2i(delta2_left.start()), p2i(delta2_left.end()),
408 p2i(delta2_right.start()), p2i(delta2_right.end()));
409 }
410 #endif // NOT PRODUCT
411
412 void PSYoungGen::resize_spaces(size_t requested_eden_size,
413 size_t requested_survivor_size) {
414 assert(UseAdaptiveSizePolicy, "sanity check");
415 assert(requested_eden_size > 0 && requested_survivor_size > 0,
416 "just checking");
417
418 // We require eden and to space to be empty
419 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
420 return;
421 }
422
423 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")",
424 requested_eden_size, requested_survivor_size);
425 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
426 p2i(eden_space()->bottom()),
427 p2i(eden_space()->end()),
428 pointer_delta(eden_space()->end(),
429 eden_space()->bottom(),
430 sizeof(char)));
431 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
432 p2i(from_space()->bottom()),
433 p2i(from_space()->end()),
434 pointer_delta(from_space()->end(),
435 from_space()->bottom(),
436 sizeof(char)));
437 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
438 p2i(to_space()->bottom()),
439 p2i(to_space()->end()),
440 pointer_delta( to_space()->end(),
441 to_space()->bottom(),
442 sizeof(char)));
443
444 // There's nothing to do if the new sizes are the same as the current
445 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
446 requested_survivor_size == from_space()->capacity_in_bytes() &&
447 requested_eden_size == eden_space()->capacity_in_bytes()) {
448 log_trace(gc, ergo)(" capacities are the right sizes, returning");
449 return;
450 }
451
452 char* eden_start = (char*)eden_space()->bottom();
453 char* eden_end = (char*)eden_space()->end();
454 char* from_start = (char*)from_space()->bottom();
455 char* from_end = (char*)from_space()->end();
456 char* to_start = (char*)to_space()->bottom();
457 char* to_end = (char*)to_space()->end();
458
459 const bool maintain_minimum =
460 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
461
462 bool eden_from_to_order = from_start < to_start;
463 // Check whether from space is below to space
464 if (eden_from_to_order) {
465 // Eden, from, to
466 eden_from_to_order = true;
467 log_trace(gc, ergo)(" Eden, from, to:");
468
469 // Set eden
470 // "requested_eden_size" is a goal for the size of eden
471 // and may not be attainable. "eden_size" below is
472 // calculated based on the location of from-space and
473 // the goal for the size of eden. from-space is
474 // fixed in place because it contains live data.
475 // The calculation is done this way to avoid 32bit
476 // overflow (i.e., eden_start + requested_eden_size
477 // may too large for representation in 32bits).
478 size_t eden_size;
479 if (maintain_minimum) {
480 // Only make eden larger than the requested size if
481 // the minimum size of the generation has to be maintained.
482 // This could be done in general but policy at a higher
483 // level is determining a requested size for eden and that
484 // should be honored unless there is a fundamental reason.
485 eden_size = pointer_delta(from_start,
486 eden_start,
487 sizeof(char));
488 } else {
489 eden_size = MIN2(requested_eden_size,
490 pointer_delta(from_start, eden_start, sizeof(char)));
491 }
492
493 eden_end = eden_start + eden_size;
494 assert(eden_end >= eden_start, "addition overflowed");
495
496 // To may resize into from space as long as it is clear of live data.
497 // From space must remain page aligned, though, so we need to do some
498 // extra calculations.
499
500 // First calculate an optimal to-space
501 to_end = (char*)virtual_space()->high();
502 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
503 sizeof(char));
504
505 // Does the optimal to-space overlap from-space?
506 if (to_start < (char*)from_space()->end()) {
507 // Calculate the minimum offset possible for from_end
508 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
509
510 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
511 if (from_size == 0) {
512 from_size = SpaceAlignment;
513 } else {
514 from_size = align_up(from_size, SpaceAlignment);
515 }
516
517 from_end = from_start + from_size;
518 assert(from_end > from_start, "addition overflow or from_size problem");
519
520 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
521
522 // Now update to_start with the new from_end
523 to_start = MAX2(from_end, to_start);
524 }
525
526 guarantee(to_start != to_end, "to space is zero sized");
527
528 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
529 p2i(eden_start),
530 p2i(eden_end),
531 pointer_delta(eden_end, eden_start, sizeof(char)));
532 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
533 p2i(from_start),
534 p2i(from_end),
535 pointer_delta(from_end, from_start, sizeof(char)));
536 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
537 p2i(to_start),
538 p2i(to_end),
539 pointer_delta( to_end, to_start, sizeof(char)));
540 } else {
541 // Eden, to, from
542 log_trace(gc, ergo)(" Eden, to, from:");
543
544 // To space gets priority over eden resizing. Note that we position
545 // to space as if we were able to resize from space, even though from
546 // space is not modified.
547 // Giving eden priority was tried and gave poorer performance.
548 to_end = (char*)pointer_delta(virtual_space()->high(),
549 (char*)requested_survivor_size,
550 sizeof(char));
551 to_end = MIN2(to_end, from_start);
552 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
553 sizeof(char));
554 // if the space sizes are to be increased by several times then
555 // 'to_start' will point beyond the young generation. In this case
556 // 'to_start' should be adjusted.
557 to_start = MAX2(to_start, eden_start + SpaceAlignment);
558
559 // Compute how big eden can be, then adjust end.
560 // See comments above on calculating eden_end.
561 size_t eden_size;
562 if (maintain_minimum) {
563 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
564 } else {
565 eden_size = MIN2(requested_eden_size,
566 pointer_delta(to_start, eden_start, sizeof(char)));
567 }
568 eden_end = eden_start + eden_size;
569 assert(eden_end >= eden_start, "addition overflowed");
570
571 // Could choose to not let eden shrink
572 // to_start = MAX2(to_start, eden_end);
573
574 // Don't let eden shrink down to 0 or less.
575 eden_end = MAX2(eden_end, eden_start + SpaceAlignment);
576 to_start = MAX2(to_start, eden_end);
577
578 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
579 p2i(eden_start),
580 p2i(eden_end),
581 pointer_delta(eden_end, eden_start, sizeof(char)));
582 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
583 p2i(to_start),
584 p2i(to_end),
585 pointer_delta( to_end, to_start, sizeof(char)));
586 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
587 p2i(from_start),
588 p2i(from_end),
589 pointer_delta(from_end, from_start, sizeof(char)));
590 }
591
592
593 guarantee((HeapWord*)from_start <= from_space()->bottom(),
594 "from start moved to the right");
595 guarantee((HeapWord*)from_end >= from_space()->top(),
596 "from end moved into live data");
597 assert(is_object_aligned(eden_start), "checking alignment");
598 assert(is_object_aligned(from_start), "checking alignment");
599 assert(is_object_aligned(to_start), "checking alignment");
600
601 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
602 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
603 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
604
605 // Let's make sure the call to initialize doesn't reset "top"!
606 HeapWord* old_from_top = from_space()->top();
607
608 // For logging block below
609 size_t old_from = from_space()->capacity_in_bytes();
610 size_t old_to = to_space()->capacity_in_bytes();
611
612 if (ZapUnusedHeapArea) {
613 // NUMA is a special case because a numa space is not mangled
614 // in order to not prematurely bind its address to memory to
615 // the wrong memory (i.e., don't want the GC thread to first
616 // touch the memory). The survivor spaces are not numa
617 // spaces and are mangled.
618 if (UseNUMA) {
619 if (eden_from_to_order) {
620 mangle_survivors(from_space(), fromMR, to_space(), toMR);
621 } else {
622 mangle_survivors(to_space(), toMR, from_space(), fromMR);
623 }
624 }
625
626 // If not mangling the spaces, do some checking to verify that
627 // the spaces are already mangled.
628 // The spaces should be correctly mangled at this point so
629 // do some checking here. Note that they are not being mangled
630 // in the calls to initialize().
631 // Must check mangling before the spaces are reshaped. Otherwise,
632 // the bottom or end of one space may have moved into an area
633 // covered by another space and a failure of the check may
634 // not correctly indicate which space is not properly mangled.
635 HeapWord* limit = (HeapWord*) virtual_space()->high();
636 eden_space()->check_mangled_unused_area(limit);
637 from_space()->check_mangled_unused_area(limit);
638 to_space()->check_mangled_unused_area(limit);
639 }
640 // When an existing space is being initialized, it is not
641 // mangled because the space has been previously mangled.
642 eden_space()->initialize(edenMR,
643 SpaceDecorator::Clear,
644 SpaceDecorator::DontMangle);
645 to_space()->initialize(toMR,
646 SpaceDecorator::Clear,
647 SpaceDecorator::DontMangle);
648 from_space()->initialize(fromMR,
649 SpaceDecorator::DontClear,
650 SpaceDecorator::DontMangle);
651
652 assert(from_space()->top() == old_from_top, "from top changed!");
653
654 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ",
655 ParallelScavengeHeap::heap()->total_collections(),
656 old_from, old_to,
657 from_space()->capacity_in_bytes(),
658 to_space()->capacity_in_bytes());
659 }
660
661 void PSYoungGen::swap_spaces() {
662 MutableSpace* s = from_space();
663 _from_space = to_space();
664 _to_space = s;
665 }
666
667 size_t PSYoungGen::capacity_in_bytes() const {
668 return eden_space()->capacity_in_bytes()
669 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge
670 }
671
672
673 size_t PSYoungGen::used_in_bytes() const {
674 return eden_space()->used_in_bytes()
675 + from_space()->used_in_bytes(); // to_space() is only used during scavenge
676 }
677
678
679 size_t PSYoungGen::free_in_bytes() const {
680 return eden_space()->free_in_bytes()
681 + from_space()->free_in_bytes(); // to_space() is only used during scavenge
682 }
683
684 size_t PSYoungGen::capacity_in_words() const {
685 return eden_space()->capacity_in_words()
686 + from_space()->capacity_in_words(); // to_space() is only used during scavenge
687 }
688
689
690 size_t PSYoungGen::used_in_words() const {
691 return eden_space()->used_in_words()
692 + from_space()->used_in_words(); // to_space() is only used during scavenge
693 }
694
695
696 size_t PSYoungGen::free_in_words() const {
697 return eden_space()->free_in_words()
698 + from_space()->free_in_words(); // to_space() is only used during scavenge
699 }
700
701 void PSYoungGen::object_iterate(ObjectClosure* blk) {
702 eden_space()->object_iterate(blk);
703 from_space()->object_iterate(blk);
704 to_space()->object_iterate(blk);
705 }
706
707 void PSYoungGen::print() const { print_on(tty); }
708 void PSYoungGen::print_on(outputStream* st) const {
709 st->print(" %-15s", "PSYoungGen");
710 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
711 capacity_in_bytes()/K, used_in_bytes()/K);
712 virtual_space()->print_space_boundaries_on(st);
713 st->print(" eden"); eden_space()->print_on(st);
714 st->print(" from"); from_space()->print_on(st);
715 st->print(" to "); to_space()->print_on(st);
716 }
717
718 size_t PSYoungGen::available_to_min_gen() {
719 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
720 return virtual_space()->committed_size() - min_gen_size();
721 }
722
723 // This method assumes that from-space has live data and that
724 // any shrinkage of the young gen is limited by location of
725 // from-space.
726 size_t PSYoungGen::available_to_live() {
727 size_t delta_in_survivor = 0;
728 MutableSpace* space_shrinking = NULL;
729 if (from_space()->end() > to_space()->end()) {
730 space_shrinking = from_space();
731 } else {
732 space_shrinking = to_space();
733 }
734
735 // Include any space that is committed but not included in
736 // the survivor spaces.
737 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
738 "Survivor space beyond high end");
739 size_t unused_committed = pointer_delta(virtual_space()->high(),
740 space_shrinking->end(), sizeof(char));
741
742 if (space_shrinking->is_empty()) {
743 // Don't let the space shrink to 0
744 assert(space_shrinking->capacity_in_bytes() >= SpaceAlignment,
745 "Space is too small");
746 delta_in_survivor = space_shrinking->capacity_in_bytes() - SpaceAlignment;
747 } else {
748 delta_in_survivor = pointer_delta(space_shrinking->end(),
749 space_shrinking->top(),
750 sizeof(char));
751 }
752
753 size_t delta_in_bytes = unused_committed + delta_in_survivor;
754 delta_in_bytes = align_down(delta_in_bytes, GenAlignment);
755 return delta_in_bytes;
756 }
757
758 // Return the number of bytes available for resizing down the young
759 // generation. This is the minimum of
760 // input "bytes"
761 // bytes to the minimum young gen size
762 // bytes to the size currently being used + some small extra
763 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
764 // Allow shrinkage into the current eden but keep eden large enough
765 // to maintain the minimum young gen size
766 bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
767 return align_down(bytes, virtual_space()->alignment());
768 }
769
770 void PSYoungGen::reset_survivors_after_shrink() {
771 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
772 (HeapWord*)virtual_space()->high_boundary());
773 PSScavenge::set_subject_to_discovery_span(_reserved);
774
775 MutableSpace* space_shrinking = NULL;
776 if (from_space()->end() > to_space()->end()) {
777 space_shrinking = from_space();
778 } else {
779 space_shrinking = to_space();
780 }
781
782 HeapWord* new_end = (HeapWord*)virtual_space()->high();
783 assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
784 // Was there a shrink of the survivor space?
785 if (new_end < space_shrinking->end()) {
786 MemRegion mr(space_shrinking->bottom(), new_end);
787 space_shrinking->initialize(mr,
788 SpaceDecorator::DontClear,
789 SpaceDecorator::Mangle);
790 }
791 }
792
793 // This method currently does not expect to expand into eden (i.e.,
794 // the virtual space boundaries is expected to be consistent
795 // with the eden boundaries..
796 void PSYoungGen::post_resize() {
797 assert_locked_or_safepoint(Heap_lock);
798 assert((eden_space()->bottom() < to_space()->bottom()) &&
799 (eden_space()->bottom() < from_space()->bottom()),
800 "Eden is assumed to be below the survivor spaces");
801
802 MemRegion cmr((HeapWord*)virtual_space()->low(),
803 (HeapWord*)virtual_space()->high());
804 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
805 space_invariants();
806 }
807
808
809
810 void PSYoungGen::update_counters() {
811 if (UsePerfData) {
812 _eden_counters->update_all();
813 _from_counters->update_all();
814 _to_counters->update_all();
815 _gen_counters->update_all();
816 }
817 }
818
819 void PSYoungGen::verify() {
820 eden_space()->verify();
821 from_space()->verify();
822 to_space()->verify();
823 }
824
825 #ifndef PRODUCT
826 void PSYoungGen::record_spaces_top() {
827 assert(ZapUnusedHeapArea, "Not mangling unused space");
828 eden_space()->set_top_for_allocations();
829 from_space()->set_top_for_allocations();
830 to_space()->set_top_for_allocations();
831 }
832 #endif