Mercurial > jdk8-mips64-public > hotspot / file revision
src/share/vm/gc_implementation/parallelScavenge/asPSYoungGen.cpp@1fdb98a17101
src/share/vm/gc_implementation/parallelScavenge/asPSYoungGen.cpp
Sat, 19 Jul 2008 17:38:22 -0400
- author
- coleenp
- date
- Sat, 19 Jul 2008 17:38:22 -0400
- changeset 672
- 1fdb98a17101
- parent 631
- d1605aabd0a1
- child 704
- 850fdf70db2b
- permissions
- -rw-r--r--
6716785: implicit null checks not triggering with CompressedOops
Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes
1 /*
2 * Copyright 2003-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_asPSYoungGen.cpp.incl"
28 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
29 size_t minimum_byte_size,
30 size_t byte_size_limit) :
31 PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
32 _gen_size_limit(byte_size_limit) {
33 }
36 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
37 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 PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
42 _gen_size_limit(byte_size_limit) {
44 assert(vs->committed_size() == init_byte_size, "Cannot replace with");
46 _virtual_space = vs;
47 }
49 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
50 size_t alignment) {
51 assert(_init_gen_size != 0, "Should have a finite size");
52 _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
53 if (!_virtual_space->expand_by(_init_gen_size)) {
54 vm_exit_during_initialization("Could not reserve enough space for "
55 "object heap");
56 }
57 }
59 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
60 initialize_virtual_space(rs, alignment);
61 initialize_work();
62 }
64 size_t ASPSYoungGen::available_for_expansion() {
66 size_t current_committed_size = virtual_space()->committed_size();
67 assert((gen_size_limit() >= current_committed_size),
68 "generation size limit is wrong");
69 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
70 size_t result = gen_size_limit() - current_committed_size;
71 size_t result_aligned = align_size_down(result, heap->young_gen_alignment());
72 return result_aligned;
73 }
75 // Return the number of bytes the young gen is willing give up.
76 //
77 // Future implementations could check the survivors and if to_space is in the
78 // right place (below from_space), take a chunk from to_space.
79 size_t ASPSYoungGen::available_for_contraction() {
81 size_t uncommitted_bytes = virtual_space()->uncommitted_size();
82 if (uncommitted_bytes != 0) {
83 return uncommitted_bytes;
84 }
86 if (eden_space()->is_empty()) {
87 // Respect the minimum size for eden and for the young gen as a whole.
88 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
89 const size_t eden_alignment = heap->intra_heap_alignment();
90 const size_t gen_alignment = heap->young_gen_alignment();
92 assert(eden_space()->capacity_in_bytes() >= eden_alignment,
93 "Alignment is wrong");
94 size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
95 eden_avail = align_size_down(eden_avail, gen_alignment);
97 assert(virtual_space()->committed_size() >= min_gen_size(),
98 "minimum gen size is wrong");
99 size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
100 assert(virtual_space()->is_aligned(gen_avail), "not aligned");
102 const size_t max_contraction = MIN2(eden_avail, gen_avail);
103 // See comment for ASPSOldGen::available_for_contraction()
104 // for reasons the "increment" fraction is used.
105 PSAdaptiveSizePolicy* policy = heap->size_policy();
106 size_t result = policy->eden_increment_aligned_down(max_contraction);
107 size_t result_aligned = align_size_down(result, gen_alignment);
108 if (PrintAdaptiveSizePolicy && Verbose) {
109 gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",
110 result_aligned/K);
111 gclog_or_tty->print_cr(" max_contraction %d K", max_contraction/K);
112 gclog_or_tty->print_cr(" eden_avail %d K", eden_avail/K);
113 gclog_or_tty->print_cr(" gen_avail %d K", gen_avail/K);
114 }
115 return result_aligned;
117 }
119 return 0;
120 }
122 // The current implementation only considers to the end of eden.
123 // If to_space is below from_space, to_space is not considered.
124 // to_space can be.
125 size_t ASPSYoungGen::available_to_live() {
126 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
127 const size_t alignment = heap->intra_heap_alignment();
129 // Include any space that is committed but is not in eden.
130 size_t available = pointer_delta(eden_space()->bottom(),
131 virtual_space()->low(),
132 sizeof(char));
134 const size_t eden_capacity = eden_space()->capacity_in_bytes();
135 if (eden_space()->is_empty() && eden_capacity > alignment) {
136 available += eden_capacity - alignment;
137 }
138 return available;
139 }
141 // Similar to PSYoungGen::resize_generation() but
142 // allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
143 // expands at the low end of the virtual space
144 // moves the boundary between the generations in order to expand
145 // some additional diagnostics
146 // If no additional changes are required, this can be deleted
147 // and the changes factored back into PSYoungGen::resize_generation().
148 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
149 const size_t alignment = virtual_space()->alignment();
150 size_t orig_size = virtual_space()->committed_size();
151 bool size_changed = false;
153 // There used to be a guarantee here that
154 // (eden_size + 2*survivor_size) <= _max_gen_size
155 // This requirement is enforced by the calculation of desired_size
156 // below. It may not be true on entry since the size of the
157 // eden_size is no bounded by the generation size.
159 assert(max_size() == reserved().byte_size(), "max gen size problem?");
160 assert(min_gen_size() <= orig_size && orig_size <= max_size(),
161 "just checking");
163 // Adjust new generation size
164 const size_t eden_plus_survivors =
165 align_size_up(eden_size + 2 * survivor_size, alignment);
166 size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
167 min_gen_size());
168 assert(desired_size <= gen_size_limit(), "just checking");
170 if (desired_size > orig_size) {
171 // Grow the generation
172 size_t change = desired_size - orig_size;
173 if (!virtual_space()->expand_by(change)) {
174 return false;
175 }
176 size_changed = true;
177 } else if (desired_size < orig_size) {
178 size_t desired_change = orig_size - desired_size;
180 // How much is available for shrinking.
181 size_t available_bytes = limit_gen_shrink(desired_change);
182 size_t change = MIN2(desired_change, available_bytes);
183 virtual_space()->shrink_by(change);
184 size_changed = true;
185 } else {
186 if (Verbose && PrintGC) {
187 if (orig_size == gen_size_limit()) {
188 gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
189 SIZE_FORMAT "K", orig_size/K);
190 } else if (orig_size == min_gen_size()) {
191 gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
192 SIZE_FORMAT "K", orig_size/K);
193 }
194 }
195 }
197 if (size_changed) {
198 reset_after_change();
199 if (Verbose && PrintGC) {
200 size_t current_size = virtual_space()->committed_size();
201 gclog_or_tty->print_cr("ASPSYoung generation size changed: "
202 SIZE_FORMAT "K->" SIZE_FORMAT "K",
203 orig_size/K, current_size/K);
204 }
205 }
207 guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
208 virtual_space()->committed_size() == max_size(), "Sanity");
210 return true;
211 }
213 // Similar to PSYoungGen::resize_spaces() but
214 // eden always starts at the low end of the committed virtual space
215 // current implementation does not allow holes between the spaces
216 // _young_generation_boundary has to be reset because it changes.
217 // so additional verification
218 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
219 size_t requested_survivor_size) {
220 assert(requested_eden_size > 0 && requested_survivor_size > 0,
221 "just checking");
223 space_invariants();
225 // We require eden and to space to be empty
226 if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
227 return;
228 }
230 if (PrintAdaptiveSizePolicy && Verbose) {
231 gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
232 SIZE_FORMAT
233 ", requested_survivor_size: " SIZE_FORMAT ")",
234 requested_eden_size, requested_survivor_size);
235 gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
236 SIZE_FORMAT,
237 eden_space()->bottom(),
238 eden_space()->end(),
239 pointer_delta(eden_space()->end(),
240 eden_space()->bottom(),
241 sizeof(char)));
242 gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
243 SIZE_FORMAT,
244 from_space()->bottom(),
245 from_space()->end(),
246 pointer_delta(from_space()->end(),
247 from_space()->bottom(),
248 sizeof(char)));
249 gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
250 SIZE_FORMAT,
251 to_space()->bottom(),
252 to_space()->end(),
253 pointer_delta( to_space()->end(),
254 to_space()->bottom(),
255 sizeof(char)));
256 }
258 // There's nothing to do if the new sizes are the same as the current
259 if (requested_survivor_size == to_space()->capacity_in_bytes() &&
260 requested_survivor_size == from_space()->capacity_in_bytes() &&
261 requested_eden_size == eden_space()->capacity_in_bytes()) {
262 if (PrintAdaptiveSizePolicy && Verbose) {
263 gclog_or_tty->print_cr(" capacities are the right sizes, returning");
264 }
265 return;
266 }
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();
275 assert(eden_start < from_start, "Cannot push into from_space");
277 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
278 const size_t alignment = heap->intra_heap_alignment();
280 // Check whether from space is below to space
281 if (from_start < to_start) {
282 // Eden, from, to
283 if (PrintAdaptiveSizePolicy && Verbose) {
284 gclog_or_tty->print_cr(" Eden, from, to:");
285 }
287 // Set eden
288 // Compute how big eden can be, then adjust end.
289 // See comment in PSYoungGen::resize_spaces() on
290 // calculating eden_end.
291 const size_t eden_size = MIN2(requested_eden_size,
292 pointer_delta(from_start,
293 eden_start,
294 sizeof(char)));
295 eden_end = eden_start + eden_size;
296 assert(eden_end >= eden_start, "addition overflowed")
298 // To may resize into from space as long as it is clear of live data.
299 // From space must remain page aligned, though, so we need to do some
300 // extra calculations.
302 // First calculate an optimal to-space
303 to_end = (char*)virtual_space()->high();
304 to_start = (char*)pointer_delta(to_end,
305 (char*)requested_survivor_size,
306 sizeof(char));
308 // Does the optimal to-space overlap from-space?
309 if (to_start < (char*)from_space()->end()) {
310 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
312 // Calculate the minimum offset possible for from_end
313 size_t from_size =
314 pointer_delta(from_space()->top(), from_start, sizeof(char));
316 // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
317 if (from_size == 0) {
318 from_size = alignment;
319 } else {
320 from_size = align_size_up(from_size, alignment);
321 }
323 from_end = from_start + from_size;
324 assert(from_end > from_start, "addition overflow or from_size problem");
326 guarantee(from_end <= (char*)from_space()->end(),
327 "from_end moved to the right");
329 // Now update to_start with the new from_end
330 to_start = MAX2(from_end, to_start);
331 }
333 guarantee(to_start != to_end, "to space is zero sized");
335 if (PrintAdaptiveSizePolicy && Verbose) {
336 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
337 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
338 eden_start,
339 eden_end,
340 pointer_delta(eden_end, eden_start, sizeof(char)));
341 gclog_or_tty->print_cr(" [from_start .. from_end): "
342 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
343 from_start,
344 from_end,
345 pointer_delta(from_end, from_start, sizeof(char)));
346 gclog_or_tty->print_cr(" [ to_start .. to_end): "
347 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
348 to_start,
349 to_end,
350 pointer_delta( to_end, to_start, sizeof(char)));
351 }
352 } else {
353 // Eden, to, from
354 if (PrintAdaptiveSizePolicy && Verbose) {
355 gclog_or_tty->print_cr(" Eden, to, from:");
356 }
358 // To space gets priority over eden resizing. Note that we position
359 // to space as if we were able to resize from space, even though from
360 // space is not modified.
361 // Giving eden priority was tried and gave poorer performance.
362 to_end = (char*)pointer_delta(virtual_space()->high(),
363 (char*)requested_survivor_size,
364 sizeof(char));
365 to_end = MIN2(to_end, from_start);
366 to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
367 sizeof(char));
368 // if the space sizes are to be increased by several times then
369 // 'to_start' will point beyond the young generation. In this case
370 // 'to_start' should be adjusted.
371 to_start = MAX2(to_start, eden_start + alignment);
373 // Compute how big eden can be, then adjust end.
374 // See comment in PSYoungGen::resize_spaces() on
375 // calculating eden_end.
376 const size_t eden_size = MIN2(requested_eden_size,
377 pointer_delta(to_start,
378 eden_start,
379 sizeof(char)));
380 eden_end = eden_start + eden_size;
381 assert(eden_end >= eden_start, "addition overflowed")
383 // Don't let eden shrink down to 0 or less.
384 eden_end = MAX2(eden_end, eden_start + alignment);
385 to_start = MAX2(to_start, eden_end);
387 if (PrintAdaptiveSizePolicy && Verbose) {
388 gclog_or_tty->print_cr(" [eden_start .. eden_end): "
389 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
390 eden_start,
391 eden_end,
392 pointer_delta(eden_end, eden_start, sizeof(char)));
393 gclog_or_tty->print_cr(" [ to_start .. to_end): "
394 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
395 to_start,
396 to_end,
397 pointer_delta( to_end, to_start, sizeof(char)));
398 gclog_or_tty->print_cr(" [from_start .. from_end): "
399 "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
400 from_start,
401 from_end,
402 pointer_delta(from_end, from_start, sizeof(char)));
403 }
404 }
407 guarantee((HeapWord*)from_start <= from_space()->bottom(),
408 "from start moved to the right");
409 guarantee((HeapWord*)from_end >= from_space()->top(),
410 "from end moved into live data");
411 assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
412 assert(is_object_aligned((intptr_t)from_start), "checking alignment");
413 assert(is_object_aligned((intptr_t)to_start), "checking alignment");
415 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
416 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
417 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
419 // Let's make sure the call to initialize doesn't reset "top"!
420 DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
422 // For PrintAdaptiveSizePolicy block below
423 size_t old_from = from_space()->capacity_in_bytes();
424 size_t old_to = to_space()->capacity_in_bytes();
426 eden_space()->initialize(edenMR, true);
427 to_space()->initialize(toMR , true);
428 from_space()->initialize(fromMR, false); // Note, not cleared!
429 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
431 assert(from_space()->top() == old_from_top, "from top changed!");
433 if (PrintAdaptiveSizePolicy) {
434 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
435 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
437 gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
438 "collection: %d "
439 "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
440 "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
441 heap->total_collections(),
442 old_from, old_to,
443 from_space()->capacity_in_bytes(),
444 to_space()->capacity_in_bytes());
445 gclog_or_tty->cr();
446 }
447 space_invariants();
448 }
450 void ASPSYoungGen::reset_after_change() {
451 assert_locked_or_safepoint(Heap_lock);
453 _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
454 (HeapWord*)virtual_space()->high_boundary());
455 PSScavenge::reference_processor()->set_span(_reserved);
457 HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
458 HeapWord* eden_bottom = eden_space()->bottom();
459 if (new_eden_bottom != eden_bottom) {
460 MemRegion eden_mr(new_eden_bottom, eden_space()->end());
461 eden_space()->initialize(eden_mr, true);
462 PSScavenge::set_young_generation_boundary(eden_space()->bottom());
463 }
464 MemRegion cmr((HeapWord*)virtual_space()->low(),
465 (HeapWord*)virtual_space()->high());
466 Universe::heap()->barrier_set()->resize_covered_region(cmr);
468 space_invariants();
469 }
