1 /*
2 * Copyright (c) 2003, 2013, 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_implementation/parallelScavenge/asPSYoungGen.hpp"
27 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
28 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
29 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
30 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
31 #include "gc_implementation/shared/gcUtil.hpp"
32 #include "gc_implementation/shared/spaceDecorator.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/java.hpp"
35
36 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
37 size_t minimum_byte_size,
38 size_t byte_size_limit) :
39 PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
40 _gen_size_limit(byte_size_limit) {
41 }
42
43
44 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
45 size_t init_byte_size,
46 size_t minimum_byte_size,
47 size_t byte_size_limit) :
48 //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
49 PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
50 _gen_size_limit(byte_size_limit) {
51
52 assert(vs->committed_size() == init_byte_size, "Cannot replace with");
53
54 _virtual_space = vs;
55 }
56
57 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
58 size_t alignment) {
59 assert(_init_gen_size != 0, "Should have a finite size");
60 _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
61 if (!_virtual_space->expand_by(_init_gen_size)) {
62 vm_exit_during_initialization("Could not reserve enough space for "
63 "object heap");
64 }
65 }
66
67 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
68 initialize_virtual_space(rs, alignment);
69 initialize_work();
70 }
71
72 size_t ASPSYoungGen::available_for_expansion() {
73 size_t current_committed_size = virtual_space()->committed_size();
74 assert((gen_size_limit() >= current_committed_size),
75 "generation size limit is wrong");
76 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
77 size_t result = gen_size_limit() - current_committed_size;
78 size_t result_aligned = align_size_down(result, heap->generation_alignment());
79 return result_aligned;
80 }
81
82 // Return the number of bytes the young gen is willing give up.
83 //
84 // Future implementations could check the survivors and if to_space is in the
85 // right place (below from_space), take a chunk from to_space.
86 size_t ASPSYoungGen::available_for_contraction() {
87 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
88 if (uncommitted_bytes != 0) {
89 return uncommitted_bytes;
90 }
91
92 if (eden_space()->is_empty()) {
93 // Respect the minimum size for eden and for the young gen as a whole.
94 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
95 const size_t eden_alignment = heap->space_alignment();
96 const size_t gen_alignment = heap->generation_alignment();
97
98 assert(eden_space()->capacity_in_bytes() >= eden_alignment,
99 "Alignment is wrong");
100 size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
101 eden_avail = align_size_down(eden_avail, gen_alignment);
102
103 assert(virtual_space()->committed_size() >= min_gen_size(),
104 "minimum gen size is wrong");
105 size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
106 assert(virtual_space()->is_aligned(gen_avail), "not aligned");
107
108 const size_t max_contraction = MIN2(eden_avail, gen_avail);
109 // See comment for ASPSOldGen::available_for_contraction()
110 // for reasons the "increment" fraction is used.
111 PSAdaptiveSizePolicy* policy = heap->size_policy();
112 size_t result = policy->eden_increment_aligned_down(max_contraction);
113 size_t result_aligned = align_size_down(result, gen_alignment);
114 if (PrintAdaptiveSizePolicy && Verbose) {
115 gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: " SIZE_FORMAT " K",
116 result_aligned/K);
117 gclog_or_tty->print_cr(" max_contraction " SIZE_FORMAT " K", max_contraction/K);
118 gclog_or_tty->print_cr(" eden_avail " SIZE_FORMAT " K", eden_avail/K);
119 gclog_or_tty->print_cr(" gen_avail " SIZE_FORMAT " K", gen_avail/K);
120 }
121 return result_aligned;
122 }
123
124 return 0;
125 }
126
127 // The current implementation only considers to the end of eden.
128 // If to_space is below from_space, to_space is not considered.
129 // to_space can be.
130 size_t ASPSYoungGen::available_to_live() {
131 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
132 const size_t alignment = heap->space_alignment();
133
134 // Include any space that is committed but is not in eden.
135 size_t available = pointer_delta(eden_space()->bottom(),
136 virtual_space()->low(),
137 sizeof(char));
138
139 const size_t eden_capacity = eden_space()->capacity_in_bytes();
140 if (eden_space()->is_empty() && eden_capacity > alignment) {
141 available += eden_capacity - alignment;
142 }
143 return available;
144 }
145
146 // Similar to PSYoungGen::resize_generation() but
147 // allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
148 // expands at the low end of the virtual space
149 // moves the boundary between the generations in order to expand
150 // some additional diagnostics
151 // If no additional changes are required, this can be deleted
152 // and the changes factored back into PSYoungGen::resize_generation().
153 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
154 const size_t alignment = virtual_space()->alignment();
155 size_t orig_size = virtual_space()->committed_size();
156 bool size_changed = false;
157
158 // There used to be a guarantee here that
159 // (eden_size + 2*survivor_size) <= _max_gen_size
160 // This requirement is enforced by the calculation of desired_size
161 // below. It may not be true on entry since the size of the
162 // eden_size is no bounded by the generation size.
163
164 assert(max_size() == reserved().byte_size(), "max gen size problem?");
165 assert(min_gen_size() <= orig_size && orig_size <= max_size(),
166 "just checking");
167
168 // Adjust new generation size
169 const size_t eden_plus_survivors =
170 align_size_up(eden_size + 2 * survivor_size, alignment);
171 size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
172 min_gen_size());
173 assert(desired_size <= gen_size_limit(), "just checking");
174
175 if (desired_size > orig_size) {
176 // Grow the generation
177 size_t change = desired_size - orig_size;
178 HeapWord* prev_low = (HeapWord*) virtual_space()->low();
179 if (!virtual_space()->expand_by(change)) {
180 return false;
181 }
182 if (ZapUnusedHeapArea) {
183 // Mangle newly committed space immediately because it
184 // can be done here more simply that after the new
185 // spaces have been computed.
186 HeapWord* new_low = (HeapWord*) virtual_space()->low();
187 assert(new_low < prev_low, "Did not grow");
188
189 MemRegion mangle_region(new_low, prev_low);
190 SpaceMangler::mangle_region(mangle_region);
191 }
192 size_changed = true;
193 } else if (desired_size < orig_size) {
194 size_t desired_change = orig_size - desired_size;
195
196 // How much is available for shrinking.
197 size_t available_bytes = limit_gen_shrink(desired_change);
198 size_t change = MIN2(desired_change, available_bytes);
199 virtual_space()->shrink_by(change);
200 size_changed = true;
201 } else {
202 if (Verbose && PrintGC) {
203 if (orig_size == gen_size_limit()) {
204 gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
205 SIZE_FORMAT "K", orig_size/K);
206 } else if (orig_size == min_gen_size()) {
207 gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
208 SIZE_FORMAT "K", orig_size/K);
209 }
210 }
211 }
212
213 if (size_changed) {
214 reset_after_change();
215 if (Verbose && PrintGC) {
216 size_t current_size = virtual_space()->committed_size();
217 gclog_or_tty->print_cr("ASPSYoung generation size changed: "
218 SIZE_FORMAT "K->" SIZE_FORMAT "K",
219 orig_size/K, current_size/K);
220 }
221 }
222
223 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
224 virtual_space()->committed_size() == max_size(), "Sanity");
225
226 return true;
227 }
228
229 // Similar to PSYoungGen::resize_spaces() but
230 // eden always starts at the low end of the committed virtual space
231 // current implementation does not allow holes between the spaces
232 // _young_generation_boundary has to be reset because it changes.
233 // so additional verification
234
235 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
236 size_t requested_survivor_size) {
237 assert(UseAdaptiveSizePolicy, "sanity check");
238 assert(requested_eden_size > 0 && requested_survivor_size > 0,
239 "just checking");
240
241 space_invariants();
242
243 // We require eden and to space to be empty
244 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
245 return;
246 }
247
248 if (PrintAdaptiveSizePolicy && Verbose) {
249 gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
250 SIZE_FORMAT
251 ", requested_survivor_size: " SIZE_FORMAT ")",
252 requested_eden_size, requested_survivor_size);
253 gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
254 SIZE_FORMAT,
255 eden_space()->bottom(),
256 eden_space()->end(),
257 pointer_delta(eden_space()->end(),
258 eden_space()->bottom(),
259 sizeof(char)));
260 gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
261 SIZE_FORMAT,
262 from_space()->bottom(),
263 from_space()->end(),
264 pointer_delta(from_space()->end(),
265 from_space()->bottom(),
266 sizeof(char)));
267 gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
268 SIZE_FORMAT,
269 to_space()->bottom(),
270 to_space()->end(),
271 pointer_delta( to_space()->end(),
272 to_space()->bottom(),
273 sizeof(char)));
274 }
275
276 // There's nothing to do if the new sizes are the same as the current
277 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
278 requested_survivor_size == from_space()->capacity_in_bytes() &&
279 requested_eden_size == eden_space()->capacity_in_bytes()) {
280 if (PrintAdaptiveSizePolicy && Verbose) {
281 gclog_or_tty->print_cr(" capacities are the right sizes, returning");
282 }
283 return;
284 }
285
286 char* eden_start = (char*)virtual_space()->low();
287 char* eden_end = (char*)eden_space()->end();
288 char* from_start = (char*)from_space()->bottom();
289 char* from_end = (char*)from_space()->end();
290 char* to_start = (char*)to_space()->bottom();
291 char* to_end = (char*)to_space()->end();
292
293 assert(eden_start < from_start, "Cannot push into from_space");
294
295 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
296 const size_t alignment = heap->space_alignment();
297 const bool maintain_minimum =
298 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
299
300 bool eden_from_to_order = from_start < to_start;
301 // Check whether from space is below to space
302 if (eden_from_to_order) {
303 // Eden, from, to
304
305 if (PrintAdaptiveSizePolicy && Verbose) {
306 gclog_or_tty->print_cr(" Eden, from, to:");
307 }
308
309 // Set eden
310 // "requested_eden_size" is a goal for the size of eden
311 // and may not be attainable. "eden_size" below is
312 // calculated based on the location of from-space and
313 // the goal for the size of eden. from-space is
314 // fixed in place because it contains live data.
315 // The calculation is done this way to avoid 32bit
316 // overflow (i.e., eden_start + requested_eden_size
317 // may too large for representation in 32bits).
318 size_t eden_size;
319 if (maintain_minimum) {
320 // Only make eden larger than the requested size if
321 // the minimum size of the generation has to be maintained.
322 // This could be done in general but policy at a higher
323 // level is determining a requested size for eden and that
324 // should be honored unless there is a fundamental reason.
325 eden_size = pointer_delta(from_start,
326 eden_start,
327 sizeof(char));
328 } else {
329 eden_size = MIN2(requested_eden_size,
330 pointer_delta(from_start, eden_start, sizeof(char)));
331 }
332
333 eden_end = eden_start + eden_size;
334 assert(eden_end >= eden_start, "addition overflowed");
335
336 // To may resize into from space as long as it is clear of live data.
337 // From space must remain page aligned, though, so we need to do some
338 // extra calculations.
339
340 // First calculate an optimal to-space
341 to_end = (char*)virtual_space()->high();
342 to_start = (char*)pointer_delta(to_end,
343 (char*)requested_survivor_size,
344 sizeof(char));
345
346 // Does the optimal to-space overlap from-space?
347 if (to_start < (char*)from_space()->end()) {
348 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
349
350 // Calculate the minimum offset possible for from_end
351 size_t from_size =
352 pointer_delta(from_space()->top(), from_start, sizeof(char));
353
354 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
355 if (from_size == 0) {
356 from_size = alignment;
357 } else {
358 from_size = align_size_up(from_size, alignment);
359 }
360
361 from_end = from_start + from_size;
362 assert(from_end > from_start, "addition overflow or from_size problem");
363
364 guarantee(from_end <= (char*)from_space()->end(),
365 "from_end moved to the right");
366
367 // Now update to_start with the new from_end
368 to_start = MAX2(from_end, to_start);
369 }
370
371 guarantee(to_start != to_end, "to space is zero sized");
372
373 if (PrintAdaptiveSizePolicy && Verbose) {
374 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
375 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
376 eden_start,
377 eden_end,
378 pointer_delta(eden_end, eden_start, sizeof(char)));
379 gclog_or_tty->print_cr(" [from_start .. from_end): "
380 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
381 from_start,
382 from_end,
383 pointer_delta(from_end, from_start, sizeof(char)));
384 gclog_or_tty->print_cr(" [ to_start .. to_end): "
385 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
386 to_start,
387 to_end,
388 pointer_delta( to_end, to_start, sizeof(char)));
389 }
390 } else {
391 // Eden, to, from
392 if (PrintAdaptiveSizePolicy && Verbose) {
393 gclog_or_tty->print_cr(" Eden, to, from:");
394 }
395
396 // To space gets priority over eden resizing. Note that we position
397 // to space as if we were able to resize from space, even though from
398 // space is not modified.
399 // Giving eden priority was tried and gave poorer performance.
400 to_end = (char*)pointer_delta(virtual_space()->high(),
401 (char*)requested_survivor_size,
402 sizeof(char));
403 to_end = MIN2(to_end, from_start);
404 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
405 sizeof(char));
406 // if the space sizes are to be increased by several times then
407 // 'to_start' will point beyond the young generation. In this case
408 // 'to_start' should be adjusted.
409 to_start = MAX2(to_start, eden_start + alignment);
410
411 // Compute how big eden can be, then adjust end.
412 // See comments above on calculating eden_end.
413 size_t eden_size;
414 if (maintain_minimum) {
415 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
416 } else {
417 eden_size = MIN2(requested_eden_size,
418 pointer_delta(to_start, eden_start, sizeof(char)));
419 }
420 eden_end = eden_start + eden_size;
421 assert(eden_end >= eden_start, "addition overflowed");
422
423 // Don't let eden shrink down to 0 or less.
424 eden_end = MAX2(eden_end, eden_start + alignment);
425 to_start = MAX2(to_start, eden_end);
426
427 if (PrintAdaptiveSizePolicy && Verbose) {
428 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
429 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
430 eden_start,
431 eden_end,
432 pointer_delta(eden_end, eden_start, sizeof(char)));
433 gclog_or_tty->print_cr(" [ to_start .. to_end): "
434 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
435 to_start,
436 to_end,
437 pointer_delta( to_end, to_start, sizeof(char)));
438 gclog_or_tty->print_cr(" [from_start .. from_end): "
439 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
440 from_start,
441 from_end,
442 pointer_delta(from_end, from_start, sizeof(char)));
443 }
444 }
445
446
447 guarantee((HeapWord*)from_start <= from_space()->bottom(),
448 "from start moved to the right");
449 guarantee((HeapWord*)from_end >= from_space()->top(),
450 "from end moved into live data");
451 assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
452 assert(is_object_aligned((intptr_t)from_start), "checking alignment");
453 assert(is_object_aligned((intptr_t)to_start), "checking alignment");
454
455 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
456 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
457 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
458
459 // Let's make sure the call to initialize doesn't reset "top"!
460 DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
461
462 // For PrintAdaptiveSizePolicy block below
463 size_t old_from = from_space()->capacity_in_bytes();
464 size_t old_to = to_space()->capacity_in_bytes();
465
466 if (ZapUnusedHeapArea) {
467 // NUMA is a special case because a numa space is not mangled
468 // in order to not prematurely bind its address to memory to
469 // the wrong memory (i.e., don't want the GC thread to first
470 // touch the memory). The survivor spaces are not numa
471 // spaces and are mangled.
472 if (UseNUMA) {
473 if (eden_from_to_order) {
474 mangle_survivors(from_space(), fromMR, to_space(), toMR);
475 } else {
476 mangle_survivors(to_space(), toMR, from_space(), fromMR);
477 }
478 }
479
480 // If not mangling the spaces, do some checking to verify that
481 // the spaces are already mangled.
482 // The spaces should be correctly mangled at this point so
483 // do some checking here. Note that they are not being mangled
484 // in the calls to initialize().
485 // Must check mangling before the spaces are reshaped. Otherwise,
486 // the bottom or end of one space may have moved into an area
487 // covered by another space and a failure of the check may
488 // not correctly indicate which space is not properly mangled.
489
490 HeapWord* limit = (HeapWord*) virtual_space()->high();
491 eden_space()->check_mangled_unused_area(limit);
492 from_space()->check_mangled_unused_area(limit);
493 to_space()->check_mangled_unused_area(limit);
494 }
495 // When an existing space is being initialized, it is not
496 // mangled because the space has been previously mangled.
497 eden_space()->initialize(edenMR,
498 SpaceDecorator::Clear,
499 SpaceDecorator::DontMangle);
500 to_space()->initialize(toMR,
501 SpaceDecorator::Clear,
502 SpaceDecorator::DontMangle);
503 from_space()->initialize(fromMR,
504 SpaceDecorator::DontClear,
505 SpaceDecorator::DontMangle);
506
507 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
508
509 assert(from_space()->top() == old_from_top, "from top changed!");
510
511 if (PrintAdaptiveSizePolicy) {
512 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
513 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
514
515 gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
516 "collection: %d "
517 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
518 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
519 heap->total_collections(),
520 old_from, old_to,
521 from_space()->capacity_in_bytes(),
522 to_space()->capacity_in_bytes());
523 gclog_or_tty->cr();
524 }
525 space_invariants();
526 }
527 void ASPSYoungGen::reset_after_change() {
528 assert_locked_or_safepoint(Heap_lock);
529
530 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
531 (HeapWord*)virtual_space()->high_boundary());
532 PSScavenge::reference_processor()->set_span(_reserved);
533
534 HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
535 HeapWord* eden_bottom = eden_space()->bottom();
536 if (new_eden_bottom != eden_bottom) {
537 MemRegion eden_mr(new_eden_bottom, eden_space()->end());
538 eden_space()->initialize(eden_mr,
539 SpaceDecorator::Clear,
540 SpaceDecorator::Mangle);
541 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
542 }
543 MemRegion cmr((HeapWord*)virtual_space()->low(),
544 (HeapWord*)virtual_space()->high());
545 Universe::heap()->barrier_set()->resize_covered_region(cmr);
546
547 space_invariants();
548 }