1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)asPSYoungGen.cpp 1.24 07/10/04 10:49:36 JVM"
3 #endif
4 /*
5 * Copyright 2003-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 # include "incls/_precompiled.incl"
29 # include "incls/_asPSYoungGen.cpp.incl"
30
31 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
32 size_t minimum_byte_size,
33 size_t byte_size_limit) :
34 PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
35 _gen_size_limit(byte_size_limit) {
36 }
37
38
39 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
40 size_t init_byte_size,
41 size_t minimum_byte_size,
42 size_t byte_size_limit) :
43 //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
44 PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
45 _gen_size_limit(byte_size_limit) {
46
47 assert(vs->committed_size() == init_byte_size, "Cannot replace with");
48
49 _virtual_space = vs;
50 }
51
52 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
53 size_t alignment) {
54 assert(_init_gen_size != 0, "Should have a finite size");
55 _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
56 if (!_virtual_space->expand_by(_init_gen_size)) {
57 vm_exit_during_initialization("Could not reserve enough space for "
58 "object heap");
59 }
60 }
61
62 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
63 initialize_virtual_space(rs, alignment);
64 initialize_work();
65 }
66
67 size_t ASPSYoungGen::available_for_expansion() {
68
69 size_t current_committed_size = virtual_space()->committed_size();
70 assert((gen_size_limit() >= current_committed_size),
71 "generation size limit is wrong");
72 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
73 size_t result = gen_size_limit() - current_committed_size;
74 size_t result_aligned = align_size_down(result, heap->young_gen_alignment());
75 return result_aligned;
76 }
77
78 // Return the number of bytes the young gen is willing give up.
79 //
80 // Future implementations could check the survivors and if to_space is in the
81 // right place (below from_space), take a chunk from to_space.
82 size_t ASPSYoungGen::available_for_contraction() {
83
84 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
85 if (uncommitted_bytes != 0) {
86 return uncommitted_bytes;
87 }
88
89 if (eden_space()->is_empty()) {
90 // Respect the minimum size for eden and for the young gen as a whole.
91 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
92 const size_t eden_alignment = heap->intra_heap_alignment();
93 const size_t gen_alignment = heap->young_gen_alignment();
94
95 assert(eden_space()->capacity_in_bytes() >= eden_alignment,
96 "Alignment is wrong");
97 size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
98 eden_avail = align_size_down(eden_avail, gen_alignment);
99
100 assert(virtual_space()->committed_size() >= min_gen_size(),
101 "minimum gen size is wrong");
102 size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
103 assert(virtual_space()->is_aligned(gen_avail), "not aligned");
104
105 const size_t max_contraction = MIN2(eden_avail, gen_avail);
106 // See comment for ASPSOldGen::available_for_contraction()
107 // for reasons the "increment" fraction is used.
108 PSAdaptiveSizePolicy* policy = heap->size_policy();
109 size_t result = policy->eden_increment_aligned_down(max_contraction);
110 size_t result_aligned = align_size_down(result, gen_alignment);
111 if (PrintAdaptiveSizePolicy && Verbose) {
112 gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",
113 result_aligned/K);
114 gclog_or_tty->print_cr(" max_contraction %d K", max_contraction/K);
115 gclog_or_tty->print_cr(" eden_avail %d K", eden_avail/K);
116 gclog_or_tty->print_cr(" gen_avail %d K", gen_avail/K);
117 }
118 return result_aligned;
119
120 }
121
122 return 0;
123 }
124
125 // The current implementation only considers to the end of eden.
126 // If to_space is below from_space, to_space is not considered.
127 // to_space can be.
128 size_t ASPSYoungGen::available_to_live() {
129 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
130 const size_t alignment = heap->intra_heap_alignment();
131
132 // Include any space that is committed but is not in eden.
133 size_t available = pointer_delta(eden_space()->bottom(),
134 virtual_space()->low(),
135 sizeof(char));
136
137 const size_t eden_capacity = eden_space()->capacity_in_bytes();
138 if (eden_space()->is_empty() && eden_capacity > alignment) {
139 available += eden_capacity - alignment;
140 }
141 return available;
142 }
143
144 // Similar to PSYoungGen::resize_generation() but
145 // allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
146 // expands at the low end of the virtual space
147 // moves the boundary between the generations in order to expand
148 // some additional diagnostics
149 // If no additional changes are required, this can be deleted
150 // and the changes factored back into PSYoungGen::resize_generation().
151 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
152 const size_t alignment = virtual_space()->alignment();
153 size_t orig_size = virtual_space()->committed_size();
154 bool size_changed = false;
155
156 // There used to be a guarantee here that
157 // (eden_size + 2*survivor_size) <= _max_gen_size
158 // This requirement is enforced by the calculation of desired_size
159 // below. It may not be true on entry since the size of the
160 // eden_size is no bounded by the generation size.
161
162 assert(max_size() == reserved().byte_size(), "max gen size problem?");
163 assert(min_gen_size() <= orig_size && orig_size <= max_size(),
164 "just checking");
165
166 // Adjust new generation size
167 const size_t eden_plus_survivors =
168 align_size_up(eden_size + 2 * survivor_size, alignment);
169 size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
170 min_gen_size());
171 assert(desired_size <= gen_size_limit(), "just checking");
172
173 if (desired_size > orig_size) {
174 // Grow the generation
175 size_t change = desired_size - orig_size;
176 HeapWord* prev_low = (HeapWord*) virtual_space()->low();
177 if (!virtual_space()->expand_by(change)) {
178 return false;
179 }
180 if (ZapUnusedHeapArea) {
181 // Mangle newly committed space immediately because it
182 // can be done here more simply that after the new
183 // spaces have been computed.
184 HeapWord* new_low = (HeapWord*) virtual_space()->low();
185 assert(new_low < prev_low, "Did not grow");
186
187 MemRegion mangle_region(new_low, prev_low);
188 SpaceMangler::mangle_region(mangle_region);
189 }
190 size_changed = true;
191 } else if (desired_size < orig_size) {
192 size_t desired_change = orig_size - desired_size;
193
194 // How much is available for shrinking.
195 size_t available_bytes = limit_gen_shrink(desired_change);
196 size_t change = MIN2(desired_change, available_bytes);
197 virtual_space()->shrink_by(change);
198 size_changed = true;
199 } else {
200 if (Verbose && PrintGC) {
201 if (orig_size == gen_size_limit()) {
202 gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
203 SIZE_FORMAT "K", orig_size/K);
204 } else if (orig_size == min_gen_size()) {
205 gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
206 SIZE_FORMAT "K", orig_size/K);
207 }
208 }
209 }
210
211 if (size_changed) {
212 reset_after_change();
213 if (Verbose && PrintGC) {
214 size_t current_size = virtual_space()->committed_size();
215 gclog_or_tty->print_cr("ASPSYoung generation size changed: "
216 SIZE_FORMAT "K->" SIZE_FORMAT "K",
217 orig_size/K, current_size/K);
218 }
219 }
220
221 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
222 virtual_space()->committed_size() == max_size(), "Sanity");
223
224 return true;
225 }
226
227 // Similar to PSYoungGen::resize_spaces() but
228 // eden always starts at the low end of the committed virtual space
229 // current implementation does not allow holes between the spaces
230 // _young_generation_boundary has to be reset because it changes.
231 // so additional verification
232
233 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
234 size_t requested_survivor_size) {
235 assert(UseAdaptiveSizePolicy, "sanity check");
236 assert(requested_eden_size > 0 && requested_survivor_size > 0,
237 "just checking");
238
239 space_invariants();
240
241 // We require eden and to space to be empty
242 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
243 return;
244 }
245
246 if (PrintAdaptiveSizePolicy && Verbose) {
247 gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
248 SIZE_FORMAT
249 ", requested_survivor_size: " SIZE_FORMAT ")",
250 requested_eden_size, requested_survivor_size);
251 gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
252 SIZE_FORMAT,
253 eden_space()->bottom(),
254 eden_space()->end(),
255 pointer_delta(eden_space()->end(),
256 eden_space()->bottom(),
257 sizeof(char)));
258 gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
259 SIZE_FORMAT,
260 from_space()->bottom(),
261 from_space()->end(),
262 pointer_delta(from_space()->end(),
263 from_space()->bottom(),
264 sizeof(char)));
265 gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
266 SIZE_FORMAT,
267 to_space()->bottom(),
268 to_space()->end(),
269 pointer_delta( to_space()->end(),
270 to_space()->bottom(),
271 sizeof(char)));
272 }
273
274 // There's nothing to do if the new sizes are the same as the current
275 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
276 requested_survivor_size == from_space()->capacity_in_bytes() &&
277 requested_eden_size == eden_space()->capacity_in_bytes()) {
278 if (PrintAdaptiveSizePolicy && Verbose) {
279 gclog_or_tty->print_cr(" capacities are the right sizes, returning");
280 }
281 return;
282 }
283
284 char* eden_start = (char*)virtual_space()->low();
285 char* eden_end = (char*)eden_space()->end();
286 char* from_start = (char*)from_space()->bottom();
287 char* from_end = (char*)from_space()->end();
288 char* to_start = (char*)to_space()->bottom();
289 char* to_end = (char*)to_space()->end();
290
291 assert(eden_start < from_start, "Cannot push into from_space");
292
293 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
294 const size_t alignment = heap->intra_heap_alignment();
295 const bool maintain_minimum =
296 (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
297
298 bool eden_from_to_order = from_start < to_start;
299 // Check whether from space is below to space
300 if (eden_from_to_order) {
301 // Eden, from, to
302
303 if (PrintAdaptiveSizePolicy && Verbose) {
304 gclog_or_tty->print_cr(" Eden, from, to:");
305 }
306
307 // Set eden
308 // "requested_eden_size" is a goal for the size of eden
309 // and may not be attainable. "eden_size" below is
310 // calculated based on the location of from-space and
311 // the goal for the size of eden. from-space is
312 // fixed in place because it contains live data.
313 // The calculation is done this way to avoid 32bit
314 // overflow (i.e., eden_start + requested_eden_size
315 // may too large for representation in 32bits).
316 size_t eden_size;
317 if (maintain_minimum) {
318 // Only make eden larger than the requested size if
319 // the minimum size of the generation has to be maintained.
320 // This could be done in general but policy at a higher
321 // level is determining a requested size for eden and that
322 // should be honored unless there is a fundamental reason.
323 eden_size = pointer_delta(from_start,
324 eden_start,
325 sizeof(char));
326 } else {
327 eden_size = MIN2(requested_eden_size,
328 pointer_delta(from_start, eden_start, sizeof(char)));
329 }
330
331 eden_end = eden_start + eden_size;
332 assert(eden_end >= eden_start, "addition overflowed")
333
334 // To may resize into from space as long as it is clear of live data.
335 // From space must remain page aligned, though, so we need to do some
336 // extra calculations.
337
338 // First calculate an optimal to-space
339 to_end = (char*)virtual_space()->high();
340 to_start = (char*)pointer_delta(to_end,
341 (char*)requested_survivor_size,
342 sizeof(char));
343
344 // Does the optimal to-space overlap from-space?
345 if (to_start < (char*)from_space()->end()) {
346 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
347
348 // Calculate the minimum offset possible for from_end
349 size_t from_size =
350 pointer_delta(from_space()->top(), from_start, sizeof(char));
351
352 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
353 if (from_size == 0) {
354 from_size = alignment;
355 } else {
356 from_size = align_size_up(from_size, alignment);
357 }
358
359 from_end = from_start + from_size;
360 assert(from_end > from_start, "addition overflow or from_size problem");
361
362 guarantee(from_end <= (char*)from_space()->end(),
363 "from_end moved to the right");
364
365 // Now update to_start with the new from_end
366 to_start = MAX2(from_end, to_start);
367 }
368
369 guarantee(to_start != to_end, "to space is zero sized");
370
371 if (PrintAdaptiveSizePolicy && Verbose) {
372 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
373 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
374 eden_start,
375 eden_end,
376 pointer_delta(eden_end, eden_start, sizeof(char)));
377 gclog_or_tty->print_cr(" [from_start .. from_end): "
378 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
379 from_start,
380 from_end,
381 pointer_delta(from_end, from_start, sizeof(char)));
382 gclog_or_tty->print_cr(" [ to_start .. to_end): "
383 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
384 to_start,
385 to_end,
386 pointer_delta( to_end, to_start, sizeof(char)));
387 }
388 } else {
389 // Eden, to, from
390 if (PrintAdaptiveSizePolicy && Verbose) {
391 gclog_or_tty->print_cr(" Eden, to, from:");
392 }
393
394 // To space gets priority over eden resizing. Note that we position
395 // to space as if we were able to resize from space, even though from
396 // space is not modified.
397 // Giving eden priority was tried and gave poorer performance.
398 to_end = (char*)pointer_delta(virtual_space()->high(),
399 (char*)requested_survivor_size,
400 sizeof(char));
401 to_end = MIN2(to_end, from_start);
402 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
403 sizeof(char));
404 // if the space sizes are to be increased by several times then
405 // 'to_start' will point beyond the young generation. In this case
406 // 'to_start' should be adjusted.
407 to_start = MAX2(to_start, eden_start + alignment);
408
409 // Compute how big eden can be, then adjust end.
410 // See comments above on calculating eden_end.
411 size_t eden_size;
412 if (maintain_minimum) {
413 eden_size = pointer_delta(to_start, eden_start, sizeof(char));
414 } else {
415 eden_size = MIN2(requested_eden_size,
416 pointer_delta(to_start, eden_start, sizeof(char)));
417 }
418 eden_end = eden_start + eden_size;
419 assert(eden_end >= eden_start, "addition overflowed")
420
421 // Don't let eden shrink down to 0 or less.
422 eden_end = MAX2(eden_end, eden_start + alignment);
423 to_start = MAX2(to_start, eden_end);
424
425 if (PrintAdaptiveSizePolicy && Verbose) {
426 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
427 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
428 eden_start,
429 eden_end,
430 pointer_delta(eden_end, eden_start, sizeof(char)));
431 gclog_or_tty->print_cr(" [ to_start .. to_end): "
432 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
433 to_start,
434 to_end,
435 pointer_delta( to_end, to_start, sizeof(char)));
436 gclog_or_tty->print_cr(" [from_start .. from_end): "
437 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
438 from_start,
439 from_end,
440 pointer_delta(from_end, from_start, sizeof(char)));
441 }
442 }
443
444
445 guarantee((HeapWord*)from_start <= from_space()->bottom(),
446 "from start moved to the right");
447 guarantee((HeapWord*)from_end >= from_space()->top(),
448 "from end moved into live data");
449 assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
450 assert(is_object_aligned((intptr_t)from_start), "checking alignment");
451 assert(is_object_aligned((intptr_t)to_start), "checking alignment");
452
453 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
454 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
455 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
456
457 // Let's make sure the call to initialize doesn't reset "top"!
458 DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
459
460 // For PrintAdaptiveSizePolicy block below
461 size_t old_from = from_space()->capacity_in_bytes();
462 size_t old_to = to_space()->capacity_in_bytes();
463
464 if (ZapUnusedHeapArea) {
465 // NUMA is a special case because a numa space is not mangled
466 // in order to not prematurely bind its address to memory to
467 // the wrong memory (i.e., don't want the GC thread to first
468 // touch the memory). The survivor spaces are not numa
469 // spaces and are mangled.
470 if (UseNUMA) {
471 if (eden_from_to_order) {
472 mangle_survivors(from_space(), fromMR, to_space(), toMR);
473 } else {
474 mangle_survivors(to_space(), toMR, from_space(), fromMR);
475 }
476 }
477
478 // If not mangling the spaces, do some checking to verify that
479 // the spaces are already mangled.
480 // The spaces should be correctly mangled at this point so
481 // do some checking here. Note that they are not being mangled
482 // in the calls to initialize().
483 // Must check mangling before the spaces are reshaped. Otherwise,
484 // the bottom or end of one space may have moved into an area
485 // covered by another space and a failure of the check may
486 // not correctly indicate which space is not properly mangled.
487
488 HeapWord* limit = (HeapWord*) virtual_space()->high();
489 eden_space()->check_mangled_unused_area(limit);
490 from_space()->check_mangled_unused_area(limit);
491 to_space()->check_mangled_unused_area(limit);
492 }
493 // When an existing space is being initialized, it is not
494 // mangled because the space has been previously mangled.
495 eden_space()->initialize(edenMR,
496 SpaceDecorator::Clear,
497 SpaceDecorator::DontMangle);
498 to_space()->initialize(toMR,
499 SpaceDecorator::Clear,
500 SpaceDecorator::DontMangle);
501 from_space()->initialize(fromMR,
502 SpaceDecorator::DontClear,
503 SpaceDecorator::DontMangle);
504
505 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
506
507 assert(from_space()->top() == old_from_top, "from top changed!");
508
509 if (PrintAdaptiveSizePolicy) {
510 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
511 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
512
513 gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
514 "collection: %d "
515 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
516 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
517 heap->total_collections(),
518 old_from, old_to,
519 from_space()->capacity_in_bytes(),
520 to_space()->capacity_in_bytes());
521 gclog_or_tty->cr();
522 }
523 space_invariants();
524 }
525 void ASPSYoungGen::reset_after_change() {
526 assert_locked_or_safepoint(Heap_lock);
527
528 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
529 (HeapWord*)virtual_space()->high_boundary());
530 PSScavenge::reference_processor()->set_span(_reserved);
531
532 HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
533 HeapWord* eden_bottom = eden_space()->bottom();
534 if (new_eden_bottom != eden_bottom) {
535 MemRegion eden_mr(new_eden_bottom, eden_space()->end());
536 eden_space()->initialize(eden_mr,
537 SpaceDecorator::Clear,
538 SpaceDecorator::Mangle);
539 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
540 }
541 MemRegion cmr((HeapWord*)virtual_space()->low(),
542 (HeapWord*)virtual_space()->high());
543 Universe::heap()->barrier_set()->resize_covered_region(cmr);
544
545 space_invariants();
546 }