1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/parallel/mutableNUMASpace.hpp"
27 #include "gc/parallel/parallelScavengeHeap.hpp"
28 #include "gc/parallel/psMarkSweepDecorator.hpp"
29 #include "gc/parallel/psScavenge.hpp"
30 #include "gc/parallel/psYoungGen.hpp"
31 #include "gc/shared/gcUtil.hpp"
32 #include "gc/shared/spaceDecorator.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,
39 size_t min_size,
40 size_t max_size) :
41 _init_gen_size(initial_size),
42 _min_gen_size(min_size),
43 _max_gen_size(max_size)
44 {}
45
46 void PSYoungGen::initialize_virtual_space(ReservedSpace rs, size_t alignment) {
47 assert(_init_gen_size != 0, "Should have a finite size");
48 _virtual_space = new PSVirtualSpace(rs, alignment);
49 if (!virtual_space()->expand_by(_init_gen_size)) {
50 vm_exit_during_initialization("Could not reserve enough space for "
51 "object heap");
52 }
53 }
54
55 void PSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
56 initialize_virtual_space(rs, alignment);
57 initialize_work();
58 }
59
60 void PSYoungGen::initialize_work() {
61
62 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
63 (HeapWord*)virtual_space()->high_boundary());
64
65 MemRegion cmr((HeapWord*)virtual_space()->low(),
66 (HeapWord*)virtual_space()->high());
67 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
68
69 if (ZapUnusedHeapArea) {
70 // Mangle newly committed space immediately because it
71 // can be done here more simply that after the new
72 // spaces have been computed.
73 SpaceMangler::mangle_region(cmr);
74 }
75
76 if (UseNUMA) {
77 _eden_space = new MutableNUMASpace(virtual_space()->alignment());
78 } else {
79 _eden_space = new MutableSpace(virtual_space()->alignment());
80 }
81 _from_space = new MutableSpace(virtual_space()->alignment());
82 _to_space = new MutableSpace(virtual_space()->alignment());
83
84 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL) {
85 vm_exit_during_initialization("Could not allocate a young gen space");
86 }
87
88 // Allocate the mark sweep views of spaces
89 _eden_mark_sweep =
90 new PSMarkSweepDecorator(_eden_space, NULL, MarkSweepDeadRatio);
91 _from_mark_sweep =
92 new PSMarkSweepDecorator(_from_space, NULL, MarkSweepDeadRatio);
93 _to_mark_sweep =
94 new PSMarkSweepDecorator(_to_space, NULL, MarkSweepDeadRatio);
95
96 if (_eden_mark_sweep == NULL ||
97 _from_mark_sweep == NULL ||
98 _to_mark_sweep == NULL) {
99 vm_exit_during_initialization("Could not complete allocation"
100 " of the young generation");
101 }
102
103 // Generation Counters - generation 0, 3 subspaces
104 _gen_counters = new PSGenerationCounters("new", 0, 3, _min_gen_size,
105 _max_gen_size, _virtual_space);
106
107 // Compute maximum space sizes for performance counters
108 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
109 size_t alignment = heap->space_alignment();
110 size_t size = virtual_space()->reserved_size();
111
112 size_t max_survivor_size;
113 size_t max_eden_size;
114
115 if (UseAdaptiveSizePolicy) {
116 max_survivor_size = size / MinSurvivorRatio;
117
118 // round the survivor space size down to the nearest alignment
119 // and make sure its size is greater than 0.
120 max_survivor_size = align_down(max_survivor_size, alignment);
121 max_survivor_size = MAX2(max_survivor_size, alignment);
122
123 // set the maximum size of eden to be the size of the young gen
124 // less two times the minimum survivor size. The minimum survivor
125 // size for UseAdaptiveSizePolicy is one alignment.
126 max_eden_size = size - 2 * alignment;
127 } else {
128 max_survivor_size = size / InitialSurvivorRatio;
129
130 // round the survivor space size down to the nearest alignment
131 // and make sure its size is greater than 0.
132 max_survivor_size = align_down(max_survivor_size, alignment);
133 max_survivor_size = MAX2(max_survivor_size, alignment);
134
135 // set the maximum size of eden to be the size of the young gen
136 // less two times the survivor size when the generation is 100%
137 // committed. The minimum survivor size for -UseAdaptiveSizePolicy
138 // is dependent on the committed portion (current capacity) of the
139 // generation - the less space committed, the smaller the survivor
140 // space, possibly as small as an alignment. However, we are interested
141 // in the case where the young generation is 100% committed, as this
142 // is the point where eden reaches its maximum size. At this point,
143 // the size of a survivor space is max_survivor_size.
144 max_eden_size = size - 2 * max_survivor_size;
145 }
146
147 _eden_counters = new SpaceCounters("eden", 0, max_eden_size, _eden_space,
148 _gen_counters);
149 _from_counters = new SpaceCounters("s0", 1, max_survivor_size, _from_space,
150 _gen_counters);
151 _to_counters = new SpaceCounters("s1", 2, max_survivor_size, _to_space,
152 _gen_counters);
153
154 compute_initial_space_boundaries();
155 }
156
157 void PSYoungGen::compute_initial_space_boundaries() {
158 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
159
160 // Compute sizes
161 size_t alignment = heap->space_alignment();
162 size_t size = virtual_space()->committed_size();
163 assert(size >= 3 * alignment, "Young space is not large enough for eden + 2 survivors");
164
165 size_t survivor_size = size / InitialSurvivorRatio;
166 survivor_size = align_down(survivor_size, alignment);
167 // ... but never less than an alignment
168 survivor_size = MAX2(survivor_size, alignment);
169
170 // Young generation is eden + 2 survivor spaces
171 size_t eden_size = size - (2 * survivor_size);
172
173 // Now go ahead and set 'em.
174 set_space_boundaries(eden_size, survivor_size);
175 space_invariants();
176
177 if (UsePerfData) {
178 _eden_counters->update_capacity();
179 _from_counters->update_capacity();
180 _to_counters->update_capacity();
181 }
182 }
183
184 void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) {
185 assert(eden_size < virtual_space()->committed_size(), "just checking");
186 assert(eden_size > 0 && survivor_size > 0, "just checking");
187
188 // Initial layout is Eden, to, from. After swapping survivor spaces,
189 // that leaves us with Eden, from, to, which is step one in our two
190 // step resize-with-live-data procedure.
191 char *eden_start = virtual_space()->low();
192 char *to_start = eden_start + eden_size;
193 char *from_start = to_start + survivor_size;
194 char *from_end = from_start + survivor_size;
195
196 assert(from_end == virtual_space()->high(), "just checking");
197 assert(is_object_aligned(eden_start), "checking alignment");
198 assert(is_object_aligned(to_start), "checking alignment");
199 assert(is_object_aligned(from_start), "checking alignment");
200
201 MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start);
202 MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start);
203 MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end);
204
205 eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea);
206 to_space()->initialize(to_mr , true, ZapUnusedHeapArea);
207 from_space()->initialize(from_mr, true, ZapUnusedHeapArea);
208 }
209
210 #ifndef PRODUCT
211 void PSYoungGen::space_invariants() {
212 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
213 const size_t alignment = heap->space_alignment();
214
215 // Currently, our eden size cannot shrink to zero
216 guarantee(eden_space()->capacity_in_bytes() >= alignment, "eden too small");
217 guarantee(from_space()->capacity_in_bytes() >= alignment, "from too small");
218 guarantee(to_space()->capacity_in_bytes() >= alignment, "to too small");
219
220 // Relationship of spaces to each other
221 char* eden_start = (char*)eden_space()->bottom();
222 char* eden_end = (char*)eden_space()->end();
223 char* from_start = (char*)from_space()->bottom();
224 char* from_end = (char*)from_space()->end();
225 char* to_start = (char*)to_space()->bottom();
226 char* to_end = (char*)to_space()->end();
227
228 guarantee(eden_start >= virtual_space()->low(), "eden bottom");
229 guarantee(eden_start < eden_end, "eden space consistency");
230 guarantee(from_start < from_end, "from space consistency");
231 guarantee(to_start < to_end, "to space consistency");
232
233 // Check whether from space is below to space
234 if (from_start < to_start) {
235 // Eden, from, to
236 guarantee(eden_end <= from_start, "eden/from boundary");
237 guarantee(from_end <= to_start, "from/to boundary");
238 guarantee(to_end <= virtual_space()->high(), "to end");
239 } else {
240 // Eden, to, from
241 guarantee(eden_end <= to_start, "eden/to boundary");
242 guarantee(to_end <= from_start, "to/from boundary");
243 guarantee(from_end <= virtual_space()->high(), "from end");
244 }
245
246 // More checks that the virtual space is consistent with the spaces
247 assert(virtual_space()->committed_size() >=
248 (eden_space()->capacity_in_bytes() +
249 to_space()->capacity_in_bytes() +
250 from_space()->capacity_in_bytes()), "Committed size is inconsistent");
251 assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
252 "Space invariant");
253 char* eden_top = (char*)eden_space()->top();
254 char* from_top = (char*)from_space()->top();
255 char* to_top = (char*)to_space()->top();
256 assert(eden_top <= virtual_space()->high(), "eden top");
257 assert(from_top <= virtual_space()->high(), "from top");
258 assert(to_top <= virtual_space()->high(), "to top");
259
260 virtual_space()->verify();
261 }
262 #endif
263
264 void PSYoungGen::resize(size_t eden_size, size_t survivor_size) {
265 // Resize the generation if needed. If the generation resize
266 // reports false, do not attempt to resize the spaces.
267 if (resize_generation(eden_size, survivor_size)) {
268 // Then we lay out the spaces inside the generation
269 resize_spaces(eden_size, survivor_size);
270
271 space_invariants();
272
273 log_trace(gc, ergo)("Young generation size: "
274 "desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
275 " used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
276 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
277 eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(),
278 _max_gen_size, min_gen_size());
279 }
280 }
281
282
283 bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
284 const size_t alignment = virtual_space()->alignment();
285 size_t orig_size = virtual_space()->committed_size();
286 bool size_changed = false;
287
288 // There used to be this guarantee there.
289 // guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments");
290 // Code below forces this requirement. In addition the desired eden
291 // size and desired survivor sizes are desired goals and may
292 // exceed the total generation size.
293
294 assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking");
295
296 // Adjust new generation size
297 const size_t eden_plus_survivors =
298 align_up(eden_size + 2 * survivor_size, alignment);
299 size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_size()),
300 min_gen_size());
301 assert(desired_size <= max_size(), "just checking");
302
303 if (desired_size > orig_size) {
304 // Grow the generation
305 size_t change = desired_size - orig_size;
306 assert(change % alignment == 0, "just checking");
307 HeapWord* prev_high = (HeapWord*) virtual_space()->high();
308 if (!virtual_space()->expand_by(change)) {
309 return false; // Error if we fail to resize!
310 }
311 if (ZapUnusedHeapArea) {
312 // Mangle newly committed space immediately because it
313 // can be done here more simply that after the new
314 // spaces have been computed.
315 HeapWord* new_high = (HeapWord*) virtual_space()->high();
316 MemRegion mangle_region(prev_high, new_high);
317 SpaceMangler::mangle_region(mangle_region);
318 }
319 size_changed = true;
320 } else if (desired_size < orig_size) {
321 size_t desired_change = orig_size - desired_size;
322 assert(desired_change % alignment == 0, "just checking");
323
324 desired_change = limit_gen_shrink(desired_change);
325
326 if (desired_change > 0) {
327 virtual_space()->shrink_by(desired_change);
328 reset_survivors_after_shrink();
329
330 size_changed = true;
331 }
332 } else {
333 if (orig_size == gen_size_limit()) {
334 log_trace(gc)("PSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
335 } else if (orig_size == min_gen_size()) {
336 log_trace(gc)("PSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
337 }
338 }
339
340 if (size_changed) {
341 post_resize();
342 log_trace(gc)("PSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
343 orig_size/K, virtual_space()->committed_size()/K);
344 }
345
346 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
347 virtual_space()->committed_size() == max_size(), "Sanity");
348
349 return true;
350 }
351
352 #ifndef PRODUCT
353 // In the numa case eden is not mangled so a survivor space
354 // moving into a region previously occupied by a survivor
355 // may find an unmangled region. Also in the PS case eden
356 // to-space and from-space may not touch (i.e., there may be
357 // gaps between them due to movement while resizing the
358 // spaces). Those gaps must be mangled.
359 void PSYoungGen::mangle_survivors(MutableSpace* s1,
360 MemRegion s1MR,
361 MutableSpace* s2,
362 MemRegion s2MR) {
363 // Check eden and gap between eden and from-space, in deciding
364 // what to mangle in from-space. Check the gap between from-space
365 // and to-space when deciding what to mangle.
366 //
367 // +--------+ +----+ +---+
368 // | eden | |s1 | |s2 |
369 // +--------+ +----+ +---+
370 // +-------+ +-----+
371 // |s1MR | |s2MR |
372 // +-------+ +-----+
373 // All of survivor-space is properly mangled so find the
374 // upper bound on the mangling for any portion above current s1.
375 HeapWord* delta_end = MIN2(s1->bottom(), s1MR.end());
376 MemRegion delta1_left;
377 if (s1MR.start() < delta_end) {
378 delta1_left = MemRegion(s1MR.start(), delta_end);
379 s1->mangle_region(delta1_left);
380 }
381 // Find any portion to the right of the current s1.
382 HeapWord* delta_start = MAX2(s1->end(), s1MR.start());
383 MemRegion delta1_right;
384 if (delta_start < s1MR.end()) {
385 delta1_right = MemRegion(delta_start, s1MR.end());
386 s1->mangle_region(delta1_right);
387 }
388
389 // Similarly for the second survivor space except that
390 // any of the new region that overlaps with the current
391 // region of the first survivor space has already been
392 // mangled.
393 delta_end = MIN2(s2->bottom(), s2MR.end());
394 delta_start = MAX2(s2MR.start(), s1->end());
395 MemRegion delta2_left;
396 if (s2MR.start() < delta_end) {
397 delta2_left = MemRegion(s2MR.start(), delta_end);
398 s2->mangle_region(delta2_left);
399 }
400 delta_start = MAX2(s2->end(), s2MR.start());
401 MemRegion delta2_right;
402 if (delta_start < s2MR.end()) {
403 s2->mangle_region(delta2_right);
404 }
405
406 // s1
407 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
408 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
409 p2i(s1->bottom()), p2i(s1->end()),
410 p2i(s1MR.start()), p2i(s1MR.end()));
411 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
412 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
413 p2i(delta1_left.start()), p2i(delta1_left.end()),
414 p2i(delta1_right.start()), p2i(delta1_right.end()));
415
416 // s2
417 log_develop_trace(gc)("Current region: [" PTR_FORMAT ", " PTR_FORMAT ") "
418 "New region: [" PTR_FORMAT ", " PTR_FORMAT ")",
419 p2i(s2->bottom()), p2i(s2->end()),
420 p2i(s2MR.start()), p2i(s2MR.end()));
421 log_develop_trace(gc)(" Mangle before: [" PTR_FORMAT ", "
422 PTR_FORMAT ") Mangle after: [" PTR_FORMAT ", " PTR_FORMAT ")",
423 p2i(delta2_left.start()), p2i(delta2_left.end()),
424 p2i(delta2_right.start()), p2i(delta2_right.end()));
425 }
426 #endif // NOT PRODUCT
427
428 void PSYoungGen::resize_spaces(size_t requested_eden_size,
429 size_t requested_survivor_size) {
430 assert(UseAdaptiveSizePolicy, "sanity check");
431 assert(requested_eden_size > 0 && requested_survivor_size > 0,
432 "just checking");
433
434 // We require eden and to space to be empty
435 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
436 return;
437 }
438
439 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")",
440 requested_eden_size, requested_survivor_size);
441 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
442 p2i(eden_space()->bottom()),
443 p2i(eden_space()->end()),
444 pointer_delta(eden_space()->end(),
445 eden_space()->bottom(),
446 sizeof(char)));
447 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
448 p2i(from_space()->bottom()),
449 p2i(from_space()->end()),
450 pointer_delta(from_space()->end(),
451 from_space()->bottom(),
452 sizeof(char)));
453 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT,
454 p2i(to_space()->bottom()),
455 p2i(to_space()->end()),
456 pointer_delta( to_space()->end(),
457 to_space()->bottom(),
458 sizeof(char)));
459
460 // There's nothing to do if the new sizes are the same as the current
461 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
462 requested_survivor_size == from_space()->capacity_in_bytes() &&
463 requested_eden_size == eden_space()->capacity_in_bytes()) {
464 log_trace(gc, ergo)(" capacities are the right sizes, returning");
465 return;
466 }
467
468 char* eden_start = (char*)eden_space()->bottom();
469 char* eden_end = (char*)eden_space()->end();
470 char* from_start = (char*)from_space()->bottom();
471 char* from_end = (char*)from_space()->end();
472 char* to_start = (char*)to_space()->bottom();
473 char* to_end = (char*)to_space()->end();
474
475 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
476 const size_t alignment = heap->space_alignment();
477 const bool maintain_minimum =
478 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
479
480 bool eden_from_to_order = from_start < to_start;
481 // Check whether from space is below to space
482 if (eden_from_to_order) {
483 // Eden, from, to
484 eden_from_to_order = true;
485 log_trace(gc, ergo)(" Eden, from, to:");
486
487 // Set eden
488 // "requested_eden_size" is a goal for the size of eden
489 // and may not be attainable. "eden_size" below is
490 // calculated based on the location of from-space and
491 // the goal for the size of eden. from-space is
492 // fixed in place because it contains live data.
493 // The calculation is done this way to avoid 32bit
494 // overflow (i.e., eden_start + requested_eden_size
495 // may too large for representation in 32bits).
496 size_t eden_size;
497 if (maintain_minimum) {
498 // Only make eden larger than the requested size if
499 // the minimum size of the generation has to be maintained.
500 // This could be done in general but policy at a higher
501 // level is determining a requested size for eden and that
502 // should be honored unless there is a fundamental reason.
503 eden_size = pointer_delta(from_start,
504 eden_start,
505 sizeof(char));
506 } else {
507 eden_size = MIN2(requested_eden_size,
508 pointer_delta(from_start, eden_start, sizeof(char)));
509 }
510
511 eden_end = eden_start + eden_size;
512 assert(eden_end >= eden_start, "addition overflowed");
513
514 // To may resize into from space as long as it is clear of live data.
515 // From space must remain page aligned, though, so we need to do some
516 // extra calculations.
517
518 // First calculate an optimal to-space
519 to_end = (char*)virtual_space()->high();
520 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
521 sizeof(char));
522
523 // Does the optimal to-space overlap from-space?
524 if (to_start < (char*)from_space()->end()) {
525 // Calculate the minimum offset possible for from_end
526 size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
527
528 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
529 if (from_size == 0) {
530 from_size = alignment;
531 } else {
532 from_size = align_up(from_size, alignment);
533 }
534
535 from_end = from_start + from_size;
536 assert(from_end > from_start, "addition overflow or from_size problem");
537
538 guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
539
540 // Now update to_start with the new from_end
541 to_start = MAX2(from_end, to_start);
542 }
543
544 guarantee(to_start != to_end, "to space is zero sized");
545
546 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
547 p2i(eden_start),
548 p2i(eden_end),
549 pointer_delta(eden_end, eden_start, sizeof(char)));
550 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
551 p2i(from_start),
552 p2i(from_end),
553 pointer_delta(from_end, from_start, sizeof(char)));
554 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
555 p2i(to_start),
556 p2i(to_end),
557 pointer_delta( to_end, to_start, sizeof(char)));
558 } else {
559 // Eden, to, from
560 log_trace(gc, ergo)(" Eden, to, from:");
561
562 // To space gets priority over eden resizing. Note that we position
563 // to space as if we were able to resize from space, even though from
564 // space is not modified.
565 // Giving eden priority was tried and gave poorer performance.
566 to_end = (char*)pointer_delta(virtual_space()->high(),
567 (char*)requested_survivor_size,
568 sizeof(char));
569 to_end = MIN2(to_end, from_start);
570 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
571 sizeof(char));
572 // if the space sizes are to be increased by several times then
573 // 'to_start' will point beyond the young generation. In this case
574 // 'to_start' should be adjusted.
575 to_start = MAX2(to_start, eden_start + alignment);
576
577 // Compute how big eden can be, then adjust end.
578 // See comments above on calculating eden_end.
579 size_t eden_size;
580 if (maintain_minimum) {
581 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
582 } else {
583 eden_size = MIN2(requested_eden_size,
584 pointer_delta(to_start, eden_start, sizeof(char)));
585 }
586 eden_end = eden_start + eden_size;
587 assert(eden_end >= eden_start, "addition overflowed");
588
589 // Could choose to not let eden shrink
590 // to_start = MAX2(to_start, eden_end);
591
592 // Don't let eden shrink down to 0 or less.
593 eden_end = MAX2(eden_end, eden_start + alignment);
594 to_start = MAX2(to_start, eden_end);
595
596 log_trace(gc, ergo)(" [eden_start .. eden_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
597 p2i(eden_start),
598 p2i(eden_end),
599 pointer_delta(eden_end, eden_start, sizeof(char)));
600 log_trace(gc, ergo)(" [ to_start .. to_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
601 p2i(to_start),
602 p2i(to_end),
603 pointer_delta( to_end, to_start, sizeof(char)));
604 log_trace(gc, ergo)(" [from_start .. from_end): [" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
605 p2i(from_start),
606 p2i(from_end),
607 pointer_delta(from_end, from_start, sizeof(char)));
608 }
609
610
611 guarantee((HeapWord*)from_start <= from_space()->bottom(),
612 "from start moved to the right");
613 guarantee((HeapWord*)from_end >= from_space()->top(),
614 "from end moved into live data");
615 assert(is_object_aligned(eden_start), "checking alignment");
616 assert(is_object_aligned(from_start), "checking alignment");
617 assert(is_object_aligned(to_start), "checking alignment");
618
619 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
620 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
621 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
622
623 // Let's make sure the call to initialize doesn't reset "top"!
624 HeapWord* old_from_top = from_space()->top();
625
626 // For logging block below
627 size_t old_from = from_space()->capacity_in_bytes();
628 size_t old_to = to_space()->capacity_in_bytes();
629
630 if (ZapUnusedHeapArea) {
631 // NUMA is a special case because a numa space is not mangled
632 // in order to not prematurely bind its address to memory to
633 // the wrong memory (i.e., don't want the GC thread to first
634 // touch the memory). The survivor spaces are not numa
635 // spaces and are mangled.
636 if (UseNUMA) {
637 if (eden_from_to_order) {
638 mangle_survivors(from_space(), fromMR, to_space(), toMR);
639 } else {
640 mangle_survivors(to_space(), toMR, from_space(), fromMR);
641 }
642 }
643
644 // If not mangling the spaces, do some checking to verify that
645 // the spaces are already mangled.
646 // The spaces should be correctly mangled at this point so
647 // do some checking here. Note that they are not being mangled
648 // in the calls to initialize().
649 // Must check mangling before the spaces are reshaped. Otherwise,
650 // the bottom or end of one space may have moved into an area
651 // covered by another space and a failure of the check may
652 // not correctly indicate which space is not properly mangled.
653 HeapWord* limit = (HeapWord*) virtual_space()->high();
654 eden_space()->check_mangled_unused_area(limit);
655 from_space()->check_mangled_unused_area(limit);
656 to_space()->check_mangled_unused_area(limit);
657 }
658 // When an existing space is being initialized, it is not
659 // mangled because the space has been previously mangled.
660 eden_space()->initialize(edenMR,
661 SpaceDecorator::Clear,
662 SpaceDecorator::DontMangle);
663 to_space()->initialize(toMR,
664 SpaceDecorator::Clear,
665 SpaceDecorator::DontMangle);
666 from_space()->initialize(fromMR,
667 SpaceDecorator::DontClear,
668 SpaceDecorator::DontMangle);
669
670 assert(from_space()->top() == old_from_top, "from top changed!");
671
672 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: collection: %d (" SIZE_FORMAT ", " SIZE_FORMAT ") -> (" SIZE_FORMAT ", " SIZE_FORMAT ") ",
673 ParallelScavengeHeap::heap()->total_collections(),
674 old_from, old_to,
675 from_space()->capacity_in_bytes(),
676 to_space()->capacity_in_bytes());
677 }
678
679 void PSYoungGen::swap_spaces() {
680 MutableSpace* s = from_space();
681 _from_space = to_space();
682 _to_space = s;
683
684 // Now update the decorators.
685 PSMarkSweepDecorator* md = from_mark_sweep();
686 _from_mark_sweep = to_mark_sweep();
687 _to_mark_sweep = md;
688
689 assert(from_mark_sweep()->space() == from_space(), "Sanity");
690 assert(to_mark_sweep()->space() == to_space(), "Sanity");
691 }
692
693 size_t PSYoungGen::capacity_in_bytes() const {
694 return eden_space()->capacity_in_bytes()
695 + from_space()->capacity_in_bytes(); // to_space() is only used during scavenge
696 }
697
698
699 size_t PSYoungGen::used_in_bytes() const {
700 return eden_space()->used_in_bytes()
701 + from_space()->used_in_bytes(); // to_space() is only used during scavenge
702 }
703
704
705 size_t PSYoungGen::free_in_bytes() const {
706 return eden_space()->free_in_bytes()
707 + from_space()->free_in_bytes(); // to_space() is only used during scavenge
708 }
709
710 size_t PSYoungGen::capacity_in_words() const {
711 return eden_space()->capacity_in_words()
712 + from_space()->capacity_in_words(); // to_space() is only used during scavenge
713 }
714
715
716 size_t PSYoungGen::used_in_words() const {
717 return eden_space()->used_in_words()
718 + from_space()->used_in_words(); // to_space() is only used during scavenge
719 }
720
721
722 size_t PSYoungGen::free_in_words() const {
723 return eden_space()->free_in_words()
724 + from_space()->free_in_words(); // to_space() is only used during scavenge
725 }
726
727 void PSYoungGen::object_iterate(ObjectClosure* blk) {
728 eden_space()->object_iterate(blk);
729 from_space()->object_iterate(blk);
730 to_space()->object_iterate(blk);
731 }
732
733 void PSYoungGen::precompact() {
734 eden_mark_sweep()->precompact();
735 from_mark_sweep()->precompact();
736 to_mark_sweep()->precompact();
737 }
738
739 void PSYoungGen::adjust_pointers() {
740 eden_mark_sweep()->adjust_pointers();
741 from_mark_sweep()->adjust_pointers();
742 to_mark_sweep()->adjust_pointers();
743 }
744
745 void PSYoungGen::compact() {
746 eden_mark_sweep()->compact(ZapUnusedHeapArea);
747 from_mark_sweep()->compact(ZapUnusedHeapArea);
748 // Mark sweep stores preserved markOops in to space, don't disturb!
749 to_mark_sweep()->compact(false);
750 }
751
752 void PSYoungGen::print() const { print_on(tty); }
753 void PSYoungGen::print_on(outputStream* st) const {
754 st->print(" %-15s", "PSYoungGen");
755 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
756 capacity_in_bytes()/K, used_in_bytes()/K);
757 virtual_space()->print_space_boundaries_on(st);
758 st->print(" eden"); eden_space()->print_on(st);
759 st->print(" from"); from_space()->print_on(st);
760 st->print(" to "); to_space()->print_on(st);
761 }
762
763 // Note that a space is not printed before the [NAME:
764 void PSYoungGen::print_used_change(size_t prev_used) const {
765 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
766 name(), prev_used / K, used_in_bytes() / K, capacity_in_bytes() / K);
767 }
768
769 size_t PSYoungGen::available_for_expansion() {
770 ShouldNotReachHere();
771 return 0;
772 }
773
774 size_t PSYoungGen::available_for_contraction() {
775 ShouldNotReachHere();
776 return 0;
777 }
778
779 size_t PSYoungGen::available_to_min_gen() {
780 assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
781 return virtual_space()->committed_size() - min_gen_size();
782 }
783
784 // This method assumes that from-space has live data and that
785 // any shrinkage of the young gen is limited by location of
786 // from-space.
787 size_t PSYoungGen::available_to_live() {
788 size_t delta_in_survivor = 0;
789 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
790 const size_t space_alignment = heap->space_alignment();
791 const size_t gen_alignment = heap->generation_alignment();
792
793 MutableSpace* space_shrinking = NULL;
794 if (from_space()->end() > to_space()->end()) {
795 space_shrinking = from_space();
796 } else {
797 space_shrinking = to_space();
798 }
799
800 // Include any space that is committed but not included in
801 // the survivor spaces.
802 assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
803 "Survivor space beyond high end");
804 size_t unused_committed = pointer_delta(virtual_space()->high(),
805 space_shrinking->end(), sizeof(char));
806
807 if (space_shrinking->is_empty()) {
808 // Don't let the space shrink to 0
809 assert(space_shrinking->capacity_in_bytes() >= space_alignment,
810 "Space is too small");
811 delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;
812 } else {
813 delta_in_survivor = pointer_delta(space_shrinking->end(),
814 space_shrinking->top(),
815 sizeof(char));
816 }
817
818 size_t delta_in_bytes = unused_committed + delta_in_survivor;
819 delta_in_bytes = align_down(delta_in_bytes, gen_alignment);
820 return delta_in_bytes;
821 }
822
823 // Return the number of bytes available for resizing down the young
824 // generation. This is the minimum of
825 // input "bytes"
826 // bytes to the minimum young gen size
827 // bytes to the size currently being used + some small extra
828 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
829 // Allow shrinkage into the current eden but keep eden large enough
830 // to maintain the minimum young gen size
831 bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
832 return align_down(bytes, virtual_space()->alignment());
833 }
834
835 void PSYoungGen::reset_after_change() {
836 ShouldNotReachHere();
837 }
838
839 void PSYoungGen::reset_survivors_after_shrink() {
840 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
841 (HeapWord*)virtual_space()->high_boundary());
842 PSScavenge::set_subject_to_discovery_span(_reserved);
843
844 MutableSpace* space_shrinking = NULL;
845 if (from_space()->end() > to_space()->end()) {
846 space_shrinking = from_space();
847 } else {
848 space_shrinking = to_space();
849 }
850
851 HeapWord* new_end = (HeapWord*)virtual_space()->high();
852 assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
853 // Was there a shrink of the survivor space?
854 if (new_end < space_shrinking->end()) {
855 MemRegion mr(space_shrinking->bottom(), new_end);
856 space_shrinking->initialize(mr,
857 SpaceDecorator::DontClear,
858 SpaceDecorator::Mangle);
859 }
860 }
861
862 // This method currently does not expect to expand into eden (i.e.,
863 // the virtual space boundaries is expected to be consistent
864 // with the eden boundaries..
865 void PSYoungGen::post_resize() {
866 assert_locked_or_safepoint(Heap_lock);
867 assert((eden_space()->bottom() < to_space()->bottom()) &&
868 (eden_space()->bottom() < from_space()->bottom()),
869 "Eden is assumed to be below the survivor spaces");
870
871 MemRegion cmr((HeapWord*)virtual_space()->low(),
872 (HeapWord*)virtual_space()->high());
873 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(cmr);
874 space_invariants();
875 }
876
877
878
879 void PSYoungGen::update_counters() {
880 if (UsePerfData) {
881 _eden_counters->update_all();
882 _from_counters->update_all();
883 _to_counters->update_all();
884 _gen_counters->update_all();
885 }
886 }
887
888 void PSYoungGen::verify() {
889 eden_space()->verify();
890 from_space()->verify();
891 to_space()->verify();
892 }
893
894 #ifndef PRODUCT
895 void PSYoungGen::record_spaces_top() {
896 assert(ZapUnusedHeapArea, "Not mangling unused space");
897 eden_space()->set_top_for_allocations();
898 from_space()->set_top_for_allocations();
899 to_space()->set_top_for_allocations();
900 }
901 #endif