1 /*
2 * Copyright (c) 2003, 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/asPSYoungGen.hpp"
27 #include "gc/parallel/parallelScavengeHeap.hpp"
28 #include "gc/parallel/psMarkSweepDecorator.hpp"
29 #include "gc/parallel/psScavenge.inline.hpp"
30 #include "gc/parallel/psYoungGen.hpp"
31 #include "gc/shared/gcUtil.hpp"
32 #include "gc/shared/spaceDecorator.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/java.hpp"
35 #include "utilities/align.hpp"
36
37 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
38 size_t minimum_byte_size,
39 size_t byte_size_limit) :
40 PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
41 _gen_size_limit(byte_size_limit) {
42 }
43
44
45 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
46 size_t init_byte_size,
47 size_t minimum_byte_size,
48 size_t byte_size_limit) :
49 //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
50 PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
51 _gen_size_limit(byte_size_limit) {
52
53 assert(vs->committed_size() == init_byte_size, "Cannot replace with");
54
55 _virtual_space = vs;
56 }
57
58 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
59 size_t alignment) {
60 assert(_init_gen_size != 0, "Should have a finite size");
61 _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
62 if (!_virtual_space->expand_by(_init_gen_size)) {
63 vm_exit_during_initialization("Could not reserve enough space for "
64 "object heap");
65 }
66 }
67
68 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
69 initialize_virtual_space(rs, alignment);
70 initialize_work();
71 }
72
73 size_t ASPSYoungGen::available_for_expansion() {
74 size_t current_committed_size = virtual_space()->committed_size();
75 assert((gen_size_limit() >= current_committed_size),
76 "generation size limit is wrong");
77 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
78 size_t result = gen_size_limit() - current_committed_size;
79 size_t result_aligned = align_down(result, heap->generation_alignment());
80 return result_aligned;
81 }
82
83 // Return the number of bytes the young gen is willing give up.
84 //
85 // Future implementations could check the survivors and if to_space is in the
86 // right place (below from_space), take a chunk from to_space.
87 size_t ASPSYoungGen::available_for_contraction() {
88 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
89 if (uncommitted_bytes != 0) {
90 return uncommitted_bytes;
91 }
92
93 if (eden_space()->is_empty()) {
94 // Respect the minimum size for eden and for the young gen as a whole.
95 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
96 const size_t eden_alignment = heap->space_alignment();
97 const size_t gen_alignment = heap->generation_alignment();
98
99 assert(eden_space()->capacity_in_bytes() >= eden_alignment,
100 "Alignment is wrong");
101 size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
102 eden_avail = align_down(eden_avail, gen_alignment);
103
104 assert(virtual_space()->committed_size() >= min_gen_size(),
105 "minimum gen size is wrong");
106 size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
107 assert(virtual_space()->is_aligned(gen_avail), "not aligned");
108
109 const size_t max_contraction = MIN2(eden_avail, gen_avail);
110 // See comment for ASPSOldGen::available_for_contraction()
111 // for reasons the "increment" fraction is used.
112 PSAdaptiveSizePolicy* policy = heap->size_policy();
113 size_t result = policy->eden_increment_aligned_down(max_contraction);
114 size_t result_aligned = align_down(result, gen_alignment);
115
116 log_trace(gc, ergo)("ASPSYoungGen::available_for_contraction: " SIZE_FORMAT " K", result_aligned/K);
117 log_trace(gc, ergo)(" max_contraction " SIZE_FORMAT " K", max_contraction/K);
118 log_trace(gc, ergo)(" eden_avail " SIZE_FORMAT " K", eden_avail/K);
119 log_trace(gc, ergo)(" 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::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_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 (orig_size == gen_size_limit()) {
203 log_trace(gc)("ASPSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K);
204 } else if (orig_size == min_gen_size()) {
205 log_trace(gc)("ASPSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K);
206 }
207 }
208
209 if (size_changed) {
210 reset_after_change();
211 log_trace(gc)("ASPSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K",
212 orig_size/K, virtual_space()->committed_size()/K);
213 }
214
215 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
216 virtual_space()->committed_size() == max_size(), "Sanity");
217
218 return true;
219 }
220
221 // Similar to PSYoungGen::resize_spaces() but
222 // eden always starts at the low end of the committed virtual space
223 // current implementation does not allow holes between the spaces
224 // _young_generation_boundary has to be reset because it changes.
225 // so additional verification
226
227 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
228 size_t requested_survivor_size) {
229 assert(UseAdaptiveSizePolicy, "sanity check");
230 assert(requested_eden_size > 0 && requested_survivor_size > 0,
231 "just checking");
232
233 space_invariants();
234
235 // We require eden and to space to be empty
236 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
237 return;
238 }
239
240 log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: "
241 SIZE_FORMAT
242 ", requested_survivor_size: " SIZE_FORMAT ")",
243 requested_eden_size, requested_survivor_size);
244 log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
245 SIZE_FORMAT,
246 p2i(eden_space()->bottom()),
247 p2i(eden_space()->end()),
248 pointer_delta(eden_space()->end(), eden_space()->bottom(), sizeof(char)));
249 log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
250 SIZE_FORMAT,
251 p2i(from_space()->bottom()),
252 p2i(from_space()->end()),
253 pointer_delta(from_space()->end(), from_space()->bottom(), sizeof(char)));
254 log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
255 SIZE_FORMAT,
256 p2i(to_space()->bottom()),
257 p2i(to_space()->end()),
258 pointer_delta( to_space()->end(), to_space()->bottom(), sizeof(char)));
259
260 // There's nothing to do if the new sizes are the same as the current
261 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
262 requested_survivor_size == from_space()->capacity_in_bytes() &&
263 requested_eden_size == eden_space()->capacity_in_bytes()) {
264 log_trace(gc, ergo)(" capacities are the right sizes, returning");
265 return;
266 }
267
268 char* eden_start = (char*)virtual_space()->low();
269 char* eden_end = (char*)eden_space()->end();
270 char* from_start = (char*)from_space()->bottom();
271 char* from_end = (char*)from_space()->end();
272 char* to_start = (char*)to_space()->bottom();
273 char* to_end = (char*)to_space()->end();
274
275 assert(eden_start < from_start, "Cannot push into from_space");
276
277 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
278 const size_t alignment = heap->space_alignment();
279 const bool maintain_minimum =
280 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
281
282 bool eden_from_to_order = from_start < to_start;
283 // Check whether from space is below to space
284 if (eden_from_to_order) {
285 // Eden, from, to
286
287 log_trace(gc, ergo)(" Eden, from, to:");
288
289 // Set eden
290 // "requested_eden_size" is a goal for the size of eden
291 // and may not be attainable. "eden_size" below is
292 // calculated based on the location of from-space and
293 // the goal for the size of eden. from-space is
294 // fixed in place because it contains live data.
295 // The calculation is done this way to avoid 32bit
296 // overflow (i.e., eden_start + requested_eden_size
297 // may too large for representation in 32bits).
298 size_t eden_size;
299 if (maintain_minimum) {
300 // Only make eden larger than the requested size if
301 // the minimum size of the generation has to be maintained.
302 // This could be done in general but policy at a higher
303 // level is determining a requested size for eden and that
304 // should be honored unless there is a fundamental reason.
305 eden_size = pointer_delta(from_start,
306 eden_start,
307 sizeof(char));
308 } else {
309 eden_size = MIN2(requested_eden_size,
310 pointer_delta(from_start, eden_start, sizeof(char)));
311 }
312
313 eden_end = eden_start + eden_size;
314 assert(eden_end >= eden_start, "addition overflowed");
315
316 // To may resize into from space as long as it is clear of live data.
317 // From space must remain page aligned, though, so we need to do some
318 // extra calculations.
319
320 // First calculate an optimal to-space
321 to_end = (char*)virtual_space()->high();
322 to_start = (char*)pointer_delta(to_end,
323 (char*)requested_survivor_size,
324 sizeof(char));
325
326 // Does the optimal to-space overlap from-space?
327 if (to_start < (char*)from_space()->end()) {
328 // Calculate the minimum offset possible for from_end
329 size_t from_size =
330 pointer_delta(from_space()->top(), from_start, sizeof(char));
331
332 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
333 if (from_size == 0) {
334 from_size = alignment;
335 } else {
336 from_size = align_up(from_size, alignment);
337 }
338
339 from_end = from_start + from_size;
340 assert(from_end > from_start, "addition overflow or from_size problem");
341
342 guarantee(from_end <= (char*)from_space()->end(),
343 "from_end moved to the right");
344
345 // Now update to_start with the new from_end
346 to_start = MAX2(from_end, to_start);
347 }
348
349 guarantee(to_start != to_end, "to space is zero sized");
350
351 log_trace(gc, ergo)(" [eden_start .. eden_end): "
352 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
353 p2i(eden_start),
354 p2i(eden_end),
355 pointer_delta(eden_end, eden_start, sizeof(char)));
356 log_trace(gc, ergo)(" [from_start .. from_end): "
357 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
358 p2i(from_start),
359 p2i(from_end),
360 pointer_delta(from_end, from_start, sizeof(char)));
361 log_trace(gc, ergo)(" [ to_start .. to_end): "
362 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
363 p2i(to_start),
364 p2i(to_end),
365 pointer_delta( to_end, to_start, sizeof(char)));
366 } else {
367 // Eden, to, from
368 log_trace(gc, ergo)(" Eden, to, from:");
369
370 // To space gets priority over eden resizing. Note that we position
371 // to space as if we were able to resize from space, even though from
372 // space is not modified.
373 // Giving eden priority was tried and gave poorer performance.
374 to_end = (char*)pointer_delta(virtual_space()->high(),
375 (char*)requested_survivor_size,
376 sizeof(char));
377 to_end = MIN2(to_end, from_start);
378 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
379 sizeof(char));
380 // if the space sizes are to be increased by several times then
381 // 'to_start' will point beyond the young generation. In this case
382 // 'to_start' should be adjusted.
383 to_start = MAX2(to_start, eden_start + alignment);
384
385 // Compute how big eden can be, then adjust end.
386 // See comments above on calculating eden_end.
387 size_t eden_size;
388 if (maintain_minimum) {
389 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
390 } else {
391 eden_size = MIN2(requested_eden_size,
392 pointer_delta(to_start, eden_start, sizeof(char)));
393 }
394 eden_end = eden_start + eden_size;
395 assert(eden_end >= eden_start, "addition overflowed");
396
397 // Don't let eden shrink down to 0 or less.
398 eden_end = MAX2(eden_end, eden_start + alignment);
399 to_start = MAX2(to_start, eden_end);
400
401 log_trace(gc, ergo)(" [eden_start .. eden_end): "
402 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
403 p2i(eden_start),
404 p2i(eden_end),
405 pointer_delta(eden_end, eden_start, sizeof(char)));
406 log_trace(gc, ergo)(" [ to_start .. to_end): "
407 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
408 p2i(to_start),
409 p2i(to_end),
410 pointer_delta( to_end, to_start, sizeof(char)));
411 log_trace(gc, ergo)(" [from_start .. from_end): "
412 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
413 p2i(from_start),
414 p2i(from_end),
415 pointer_delta(from_end, from_start, sizeof(char)));
416 }
417
418
419 guarantee((HeapWord*)from_start <= from_space()->bottom(),
420 "from start moved to the right");
421 guarantee((HeapWord*)from_end >= from_space()->top(),
422 "from end moved into live data");
423 assert(is_object_aligned(eden_start), "checking alignment");
424 assert(is_object_aligned(from_start), "checking alignment");
425 assert(is_object_aligned(to_start), "checking alignment");
426
427 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
428 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
429 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
430
431 // Let's make sure the call to initialize doesn't reset "top"!
432 DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
433
434 // For logging block below
435 size_t old_from = from_space()->capacity_in_bytes();
436 size_t old_to = to_space()->capacity_in_bytes();
437
438 if (ZapUnusedHeapArea) {
439 // NUMA is a special case because a numa space is not mangled
440 // in order to not prematurely bind its address to memory to
441 // the wrong memory (i.e., don't want the GC thread to first
442 // touch the memory). The survivor spaces are not numa
443 // spaces and are mangled.
444 if (UseNUMA) {
445 if (eden_from_to_order) {
446 mangle_survivors(from_space(), fromMR, to_space(), toMR);
447 } else {
448 mangle_survivors(to_space(), toMR, from_space(), fromMR);
449 }
450 }
451
452 // If not mangling the spaces, do some checking to verify that
453 // the spaces are already mangled.
454 // The spaces should be correctly mangled at this point so
455 // do some checking here. Note that they are not being mangled
456 // in the calls to initialize().
457 // Must check mangling before the spaces are reshaped. Otherwise,
458 // the bottom or end of one space may have moved into an area
459 // covered by another space and a failure of the check may
460 // not correctly indicate which space is not properly mangled.
461
462 HeapWord* limit = (HeapWord*) virtual_space()->high();
463 eden_space()->check_mangled_unused_area(limit);
464 from_space()->check_mangled_unused_area(limit);
465 to_space()->check_mangled_unused_area(limit);
466 }
467 // When an existing space is being initialized, it is not
468 // mangled because the space has been previously mangled.
469 eden_space()->initialize(edenMR,
470 SpaceDecorator::Clear,
471 SpaceDecorator::DontMangle);
472 to_space()->initialize(toMR,
473 SpaceDecorator::Clear,
474 SpaceDecorator::DontMangle);
475 from_space()->initialize(fromMR,
476 SpaceDecorator::DontClear,
477 SpaceDecorator::DontMangle);
478
479 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
480
481 assert(from_space()->top() == old_from_top, "from top changed!");
482
483 log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: "
484 "collection: %d "
485 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
486 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
487 ParallelScavengeHeap::heap()->total_collections(),
488 old_from, old_to,
489 from_space()->capacity_in_bytes(),
490 to_space()->capacity_in_bytes());
491
492 space_invariants();
493 }
494 void ASPSYoungGen::reset_after_change() {
495 assert_locked_or_safepoint(Heap_lock);
496
497 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
498 (HeapWord*)virtual_space()->high_boundary());
499 PSScavenge::reference_processor()->set_span(_reserved);
500
501 HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
502 HeapWord* eden_bottom = eden_space()->bottom();
503 if (new_eden_bottom != eden_bottom) {
504 MemRegion eden_mr(new_eden_bottom, eden_space()->end());
505 eden_space()->initialize(eden_mr,
506 SpaceDecorator::Clear,
507 SpaceDecorator::Mangle);
508 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
509 }
510 MemRegion cmr((HeapWord*)virtual_space()->low(),
511 (HeapWord*)virtual_space()->high());
512 ParallelScavengeHeap::heap()->barrier_set()->card_table()->resize_covered_region(cmr);
513
514 space_invariants();
515 }