1/* 2 * Copyright (c) 2003, 2016, 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 37ASPSYoungGen::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 45ASPSYoungGen::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 58void 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 68void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) { 69 initialize_virtual_space(rs, alignment); 70 initialize_work(); 71} 72 73size_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. 87size_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. 130size_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(). 153bool 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 227void 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} 494void 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()->resize_covered_region(cmr); 513 514 space_invariants(); 515} 516