HeapSource.cpp revision fe9052edaf6bebbccaac5a9fb607012778d0dd74
1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#include <cutils/mspace.h> 18#include <stdint.h> 19#include <sys/mman.h> 20#include <errno.h> 21 22#define SIZE_MAX UINT_MAX // TODO: get SIZE_MAX from stdint.h 23 24#include "Dalvik.h" 25#include "alloc/Heap.h" 26#include "alloc/HeapInternal.h" 27#include "alloc/HeapSource.h" 28#include "alloc/HeapBitmap.h" 29#include "alloc/HeapBitmapInlines.h" 30 31// TODO: find a real header file for these. 32extern "C" int dlmalloc_trim(size_t); 33extern "C" void dlmalloc_walk_free_pages(void(*)(void*, void*, void*), void*); 34 35static void snapIdealFootprint(); 36static void setIdealFootprint(size_t max); 37static size_t getMaximumSize(const HeapSource *hs); 38static void trimHeaps(); 39 40#define HEAP_UTILIZATION_MAX 1024 41#define DEFAULT_HEAP_UTILIZATION 512 // Range 1..HEAP_UTILIZATION_MAX 42#define HEAP_IDEAL_FREE (2 * 1024 * 1024) 43#define HEAP_MIN_FREE (HEAP_IDEAL_FREE / 4) 44 45/* Number of seconds to wait after a GC before performing a heap trim 46 * operation to reclaim unused pages. 47 */ 48#define HEAP_TRIM_IDLE_TIME_SECONDS 5 49 50/* Start a concurrent collection when free memory falls under this 51 * many bytes. 52 */ 53#define CONCURRENT_START (128 << 10) 54 55/* The next GC will not be concurrent when free memory after a GC is 56 * under this many bytes. 57 */ 58#define CONCURRENT_MIN_FREE (CONCURRENT_START + (128 << 10)) 59 60#define HS_BOILERPLATE() \ 61 do { \ 62 assert(gDvm.gcHeap != NULL); \ 63 assert(gDvm.gcHeap->heapSource != NULL); \ 64 assert(gHs == gDvm.gcHeap->heapSource); \ 65 } while (0) 66 67struct Heap { 68 /* The mspace to allocate from. 69 */ 70 mspace msp; 71 72 /* The largest size that this heap is allowed to grow to. 73 */ 74 size_t maximumSize; 75 76 /* Number of bytes allocated from this mspace for objects, 77 * including any overhead. This value is NOT exact, and 78 * should only be used as an input for certain heuristics. 79 */ 80 size_t bytesAllocated; 81 82 /* Number of bytes allocated from this mspace at which a 83 * concurrent garbage collection will be started. 84 */ 85 size_t concurrentStartBytes; 86 87 /* Number of objects currently allocated from this mspace. 88 */ 89 size_t objectsAllocated; 90 91 /* 92 * The lowest address of this heap, inclusive. 93 */ 94 char *base; 95 96 /* 97 * The highest address of this heap, exclusive. 98 */ 99 char *limit; 100}; 101 102struct HeapSource { 103 /* Target ideal heap utilization ratio; range 1..HEAP_UTILIZATION_MAX 104 */ 105 size_t targetUtilization; 106 107 /* The starting heap size. 108 */ 109 size_t startSize; 110 111 /* The largest that the heap source as a whole is allowed to grow. 112 */ 113 size_t maximumSize; 114 115 /* 116 * The largest size we permit the heap to grow. This value allows 117 * the user to limit the heap growth below the maximum size. This 118 * is a work around until we can dynamically set the maximum size. 119 * This value can range between the starting size and the maximum 120 * size but should never be set below the current footprint of the 121 * heap. 122 */ 123 size_t growthLimit; 124 125 /* The desired max size of the heap source as a whole. 126 */ 127 size_t idealSize; 128 129 /* The maximum number of bytes allowed to be allocated from the 130 * active heap before a GC is forced. This is used to "shrink" the 131 * heap in lieu of actual compaction. 132 */ 133 size_t softLimit; 134 135 /* The heaps; heaps[0] is always the active heap, 136 * which new objects should be allocated from. 137 */ 138 Heap heaps[HEAP_SOURCE_MAX_HEAP_COUNT]; 139 140 /* The current number of heaps. 141 */ 142 size_t numHeaps; 143 144 /* True if zygote mode was active when the HeapSource was created. 145 */ 146 bool sawZygote; 147 148 /* 149 * The base address of the virtual memory reservation. 150 */ 151 char *heapBase; 152 153 /* 154 * The length in bytes of the virtual memory reservation. 155 */ 156 size_t heapLength; 157 158 /* 159 * The live object bitmap. 160 */ 161 HeapBitmap liveBits; 162 163 /* 164 * The mark bitmap. 165 */ 166 HeapBitmap markBits; 167 168 /* 169 * State for the GC daemon. 170 */ 171 bool hasGcThread; 172 pthread_t gcThread; 173 bool gcThreadShutdown; 174 pthread_mutex_t gcThreadMutex; 175 pthread_cond_t gcThreadCond; 176 bool gcThreadTrimNeeded; 177}; 178 179#define hs2heap(hs_) (&((hs_)->heaps[0])) 180 181/* 182 * Returns true iff a soft limit is in effect for the active heap. 183 */ 184static bool isSoftLimited(const HeapSource *hs) 185{ 186 /* softLimit will be either SIZE_MAX or the limit for the 187 * active mspace. idealSize can be greater than softLimit 188 * if there is more than one heap. If there is only one 189 * heap, a non-SIZE_MAX softLimit should always be the same 190 * as idealSize. 191 */ 192 return hs->softLimit <= hs->idealSize; 193} 194 195/* 196 * Returns approximately the maximum number of bytes allowed to be 197 * allocated from the active heap before a GC is forced. 198 */ 199static size_t getAllocLimit(const HeapSource *hs) 200{ 201 if (isSoftLimited(hs)) { 202 return hs->softLimit; 203 } else { 204 return mspace_max_allowed_footprint(hs2heap(hs)->msp); 205 } 206} 207 208/* 209 * Returns the current footprint of all heaps. If includeActive 210 * is false, don't count the heap at index 0. 211 */ 212static size_t oldHeapOverhead(const HeapSource *hs, bool includeActive) 213{ 214 size_t footprint = 0; 215 size_t i; 216 217 if (includeActive) { 218 i = 0; 219 } else { 220 i = 1; 221 } 222 for (/* i = i */; i < hs->numHeaps; i++) { 223//TODO: include size of bitmaps? If so, don't use bitsLen, listen to .max 224 footprint += mspace_footprint(hs->heaps[i].msp); 225 } 226 return footprint; 227} 228 229/* 230 * Returns the heap that <ptr> could have come from, or NULL 231 * if it could not have come from any heap. 232 */ 233static Heap *ptr2heap(const HeapSource *hs, const void *ptr) 234{ 235 const size_t numHeaps = hs->numHeaps; 236 237 if (ptr != NULL) { 238 for (size_t i = 0; i < numHeaps; i++) { 239 const Heap *const heap = &hs->heaps[i]; 240 241 if ((const char *)ptr >= heap->base && (const char *)ptr < heap->limit) { 242 return (Heap *)heap; 243 } 244 } 245 } 246 return NULL; 247} 248 249/* 250 * Functions to update heapSource->bytesAllocated when an object 251 * is allocated or freed. mspace_usable_size() will give 252 * us a much more accurate picture of heap utilization than 253 * the requested byte sizes would. 254 * 255 * These aren't exact, and should not be treated as such. 256 */ 257static void countAllocation(Heap *heap, const void *ptr) 258{ 259 assert(heap->bytesAllocated < mspace_footprint(heap->msp)); 260 261 heap->bytesAllocated += mspace_usable_size(heap->msp, ptr) + 262 HEAP_SOURCE_CHUNK_OVERHEAD; 263 heap->objectsAllocated++; 264 HeapSource* hs = gDvm.gcHeap->heapSource; 265 dvmHeapBitmapSetObjectBit(&hs->liveBits, ptr); 266 267 assert(heap->bytesAllocated < mspace_footprint(heap->msp)); 268} 269 270static void countFree(Heap *heap, const void *ptr, size_t *numBytes) 271{ 272 size_t delta = mspace_usable_size(heap->msp, ptr) + HEAP_SOURCE_CHUNK_OVERHEAD; 273 assert(delta > 0); 274 if (delta < heap->bytesAllocated) { 275 heap->bytesAllocated -= delta; 276 } else { 277 heap->bytesAllocated = 0; 278 } 279 HeapSource* hs = gDvm.gcHeap->heapSource; 280 dvmHeapBitmapClearObjectBit(&hs->liveBits, ptr); 281 if (heap->objectsAllocated > 0) { 282 heap->objectsAllocated--; 283 } 284 *numBytes += delta; 285} 286 287static HeapSource *gHs = NULL; 288 289static mspace createMspace(void *base, size_t startSize, size_t maximumSize) 290{ 291 /* Create an unlocked dlmalloc mspace to use as 292 * a heap source. 293 * 294 * We start off reserving startSize / 2 bytes but 295 * letting the heap grow to startSize. This saves 296 * memory in the case where a process uses even less 297 * than the starting size. 298 */ 299 LOGV_HEAP("Creating VM heap of size %zu", startSize); 300 errno = 0; 301 302 mspace msp = create_contiguous_mspace_with_base(startSize/2, 303 maximumSize, /*locked=*/false, base); 304 if (msp != NULL) { 305 /* Don't let the heap grow past the starting size without 306 * our intervention. 307 */ 308 mspace_set_max_allowed_footprint(msp, startSize); 309 } else { 310 /* There's no guarantee that errno has meaning when the call 311 * fails, but it often does. 312 */ 313 LOGE_HEAP("Can't create VM heap of size (%zu,%zu): %s", 314 startSize/2, maximumSize, strerror(errno)); 315 } 316 317 return msp; 318} 319 320/* 321 * Add the initial heap. Returns false if the initial heap was 322 * already added to the heap source. 323 */ 324static bool addInitialHeap(HeapSource *hs, mspace msp, size_t maximumSize) 325{ 326 assert(hs != NULL); 327 assert(msp != NULL); 328 if (hs->numHeaps != 0) { 329 return false; 330 } 331 hs->heaps[0].msp = msp; 332 hs->heaps[0].maximumSize = maximumSize; 333 hs->heaps[0].concurrentStartBytes = SIZE_MAX; 334 hs->heaps[0].base = hs->heapBase; 335 hs->heaps[0].limit = hs->heapBase + hs->heaps[0].maximumSize; 336 hs->numHeaps = 1; 337 return true; 338} 339 340/* 341 * Adds an additional heap to the heap source. Returns false if there 342 * are too many heaps or insufficient free space to add another heap. 343 */ 344static bool addNewHeap(HeapSource *hs) 345{ 346 Heap heap; 347 348 assert(hs != NULL); 349 if (hs->numHeaps >= HEAP_SOURCE_MAX_HEAP_COUNT) { 350 LOGE("Attempt to create too many heaps (%zd >= %zd)", 351 hs->numHeaps, HEAP_SOURCE_MAX_HEAP_COUNT); 352 dvmAbort(); 353 return false; 354 } 355 356 memset(&heap, 0, sizeof(heap)); 357 358 /* 359 * Heap storage comes from a common virtual memory reservation. 360 * The new heap will start on the page after the old heap. 361 */ 362 void *sbrk0 = contiguous_mspace_sbrk0(hs->heaps[0].msp); 363 char *base = (char *)ALIGN_UP_TO_PAGE_SIZE(sbrk0); 364 size_t overhead = base - hs->heaps[0].base; 365 assert(((size_t)hs->heaps[0].base & (SYSTEM_PAGE_SIZE - 1)) == 0); 366 367 if (overhead + HEAP_MIN_FREE >= hs->maximumSize) { 368 LOGE_HEAP("No room to create any more heaps " 369 "(%zd overhead, %zd max)", 370 overhead, hs->maximumSize); 371 return false; 372 } 373 374 heap.maximumSize = hs->growthLimit - overhead; 375 heap.concurrentStartBytes = HEAP_MIN_FREE - CONCURRENT_START; 376 heap.base = base; 377 heap.limit = heap.base + heap.maximumSize; 378 heap.msp = createMspace(base, HEAP_MIN_FREE, hs->maximumSize - overhead); 379 if (heap.msp == NULL) { 380 return false; 381 } 382 383 /* Don't let the soon-to-be-old heap grow any further. 384 */ 385 hs->heaps[0].maximumSize = overhead; 386 hs->heaps[0].limit = base; 387 mspace msp = hs->heaps[0].msp; 388 mspace_set_max_allowed_footprint(msp, mspace_footprint(msp)); 389 390 /* Put the new heap in the list, at heaps[0]. 391 * Shift existing heaps down. 392 */ 393 memmove(&hs->heaps[1], &hs->heaps[0], hs->numHeaps * sizeof(hs->heaps[0])); 394 hs->heaps[0] = heap; 395 hs->numHeaps++; 396 397 return true; 398} 399 400/* 401 * The garbage collection daemon. Initiates a concurrent collection 402 * when signaled. Also periodically trims the heaps when a few seconds 403 * have elapsed since the last concurrent GC. 404 */ 405static void *gcDaemonThread(void* arg) 406{ 407 dvmChangeStatus(NULL, THREAD_VMWAIT); 408 dvmLockMutex(&gHs->gcThreadMutex); 409 while (gHs->gcThreadShutdown != true) { 410 bool trim = false; 411 if (gHs->gcThreadTrimNeeded) { 412 int result = dvmRelativeCondWait(&gHs->gcThreadCond, &gHs->gcThreadMutex, 413 HEAP_TRIM_IDLE_TIME_SECONDS, 0); 414 if (result == ETIMEDOUT) { 415 /* Timed out waiting for a GC request, schedule a heap trim. */ 416 trim = true; 417 } 418 } else { 419 dvmWaitCond(&gHs->gcThreadCond, &gHs->gcThreadMutex); 420 } 421 422 dvmLockHeap(); 423 /* 424 * Another thread may have started a concurrent garbage 425 * collection before we were scheduled. Check for this 426 * condition before proceeding. 427 */ 428 if (!gDvm.gcHeap->gcRunning) { 429 dvmChangeStatus(NULL, THREAD_RUNNING); 430 if (trim) { 431 trimHeaps(); 432 gHs->gcThreadTrimNeeded = false; 433 } else { 434 dvmCollectGarbageInternal(GC_CONCURRENT); 435 gHs->gcThreadTrimNeeded = true; 436 } 437 dvmChangeStatus(NULL, THREAD_VMWAIT); 438 } 439 dvmUnlockHeap(); 440 } 441 dvmChangeStatus(NULL, THREAD_RUNNING); 442 return NULL; 443} 444 445static bool gcDaemonStartup() 446{ 447 dvmInitMutex(&gHs->gcThreadMutex); 448 pthread_cond_init(&gHs->gcThreadCond, NULL); 449 gHs->gcThreadShutdown = false; 450 gHs->hasGcThread = dvmCreateInternalThread(&gHs->gcThread, "GC", 451 gcDaemonThread, NULL); 452 return gHs->hasGcThread; 453} 454 455static void gcDaemonShutdown() 456{ 457 if (gHs->hasGcThread) { 458 dvmLockMutex(&gHs->gcThreadMutex); 459 gHs->gcThreadShutdown = true; 460 dvmSignalCond(&gHs->gcThreadCond); 461 dvmUnlockMutex(&gHs->gcThreadMutex); 462 pthread_join(gHs->gcThread, NULL); 463 } 464} 465 466/* 467 * Create a stack big enough for the worst possible case, where the 468 * heap is perfectly full of the smallest object. 469 * TODO: be better about memory usage; use a smaller stack with 470 * overflow detection and recovery. 471 */ 472static bool allocMarkStack(GcMarkStack *stack, size_t maximumSize) 473{ 474 const char *name = "dalvik-mark-stack"; 475 void *addr; 476 477 assert(stack != NULL); 478 stack->length = maximumSize * sizeof(Object*) / 479 (sizeof(Object) + HEAP_SOURCE_CHUNK_OVERHEAD); 480 addr = dvmAllocRegion(stack->length, PROT_READ | PROT_WRITE, name); 481 if (addr == NULL) { 482 return false; 483 } 484 stack->base = (const Object **)addr; 485 stack->limit = (const Object **)((char *)addr + stack->length); 486 stack->top = NULL; 487 madvise(stack->base, stack->length, MADV_DONTNEED); 488 return true; 489} 490 491static void freeMarkStack(GcMarkStack *stack) 492{ 493 assert(stack != NULL); 494 munmap(stack->base, stack->length); 495 memset(stack, 0, sizeof(*stack)); 496} 497 498/* 499 * Initializes the heap source; must be called before any other 500 * dvmHeapSource*() functions. Returns a GcHeap structure 501 * allocated from the heap source. 502 */ 503GcHeap* dvmHeapSourceStartup(size_t startSize, size_t maximumSize, 504 size_t growthLimit) 505{ 506 GcHeap *gcHeap; 507 HeapSource *hs; 508 mspace msp; 509 size_t length; 510 void *base; 511 512 assert(gHs == NULL); 513 514 if (!(startSize <= growthLimit && growthLimit <= maximumSize)) { 515 LOGE("Bad heap size parameters (start=%zd, max=%zd, limit=%zd)", 516 startSize, maximumSize, growthLimit); 517 return NULL; 518 } 519 520 /* 521 * Allocate a contiguous region of virtual memory to subdivided 522 * among the heaps managed by the garbage collector. 523 */ 524 length = ALIGN_UP_TO_PAGE_SIZE(maximumSize); 525 base = dvmAllocRegion(length, PROT_NONE, "dalvik-heap"); 526 if (base == NULL) { 527 return NULL; 528 } 529 530 /* Create an unlocked dlmalloc mspace to use as 531 * a heap source. 532 */ 533 msp = createMspace(base, startSize, maximumSize); 534 if (msp == NULL) { 535 goto fail; 536 } 537 538 gcHeap = (GcHeap *)malloc(sizeof(*gcHeap)); 539 if (gcHeap == NULL) { 540 LOGE_HEAP("Can't allocate heap descriptor"); 541 goto fail; 542 } 543 memset(gcHeap, 0, sizeof(*gcHeap)); 544 545 hs = (HeapSource *)malloc(sizeof(*hs)); 546 if (hs == NULL) { 547 LOGE_HEAP("Can't allocate heap source"); 548 free(gcHeap); 549 goto fail; 550 } 551 memset(hs, 0, sizeof(*hs)); 552 553 hs->targetUtilization = DEFAULT_HEAP_UTILIZATION; 554 hs->startSize = startSize; 555 hs->maximumSize = maximumSize; 556 hs->growthLimit = growthLimit; 557 hs->idealSize = startSize; 558 hs->softLimit = SIZE_MAX; // no soft limit at first 559 hs->numHeaps = 0; 560 hs->sawZygote = gDvm.zygote; 561 hs->hasGcThread = false; 562 hs->heapBase = (char *)base; 563 hs->heapLength = length; 564 if (!addInitialHeap(hs, msp, growthLimit)) { 565 LOGE_HEAP("Can't add initial heap"); 566 goto fail; 567 } 568 if (!dvmHeapBitmapInit(&hs->liveBits, base, length, "dalvik-bitmap-1")) { 569 LOGE_HEAP("Can't create liveBits"); 570 goto fail; 571 } 572 if (!dvmHeapBitmapInit(&hs->markBits, base, length, "dalvik-bitmap-2")) { 573 LOGE_HEAP("Can't create markBits"); 574 dvmHeapBitmapDelete(&hs->liveBits); 575 goto fail; 576 } 577 if (!allocMarkStack(&gcHeap->markContext.stack, hs->maximumSize)) { 578 LOGE("Can't create markStack"); 579 dvmHeapBitmapDelete(&hs->markBits); 580 dvmHeapBitmapDelete(&hs->liveBits); 581 goto fail; 582 } 583 gcHeap->markContext.bitmap = &hs->markBits; 584 gcHeap->heapSource = hs; 585 586 gHs = hs; 587 return gcHeap; 588 589fail: 590 munmap(base, length); 591 return NULL; 592} 593 594bool dvmHeapSourceStartupAfterZygote() 595{ 596 return gDvm.concurrentMarkSweep ? gcDaemonStartup() : true; 597} 598 599/* 600 * This is called while in zygote mode, right before we fork() for the 601 * first time. We create a heap for all future zygote process allocations, 602 * in an attempt to avoid touching pages in the zygote heap. (This would 603 * probably be unnecessary if we had a compacting GC -- the source of our 604 * troubles is small allocations filling in the gaps from larger ones.) 605 */ 606bool dvmHeapSourceStartupBeforeFork() 607{ 608 HS_BOILERPLATE(); 609 610 assert(gDvm.zygote); 611 612 if (!gDvm.newZygoteHeapAllocated) { 613 /* Create a new heap for post-fork zygote allocations. We only 614 * try once, even if it fails. 615 */ 616 LOGV("Splitting out new zygote heap"); 617 gDvm.newZygoteHeapAllocated = true; 618 dvmClearCardTable(); 619 return addNewHeap(gHs); 620 } 621 return true; 622} 623 624void dvmHeapSourceThreadShutdown() 625{ 626 if (gDvm.gcHeap != NULL && gDvm.concurrentMarkSweep) { 627 gcDaemonShutdown(); 628 } 629} 630 631/* 632 * Tears down the entire GcHeap structure and all of the substructures 633 * attached to it. This call has the side effect of setting the given 634 * gcHeap pointer and gHs to NULL. 635 */ 636void dvmHeapSourceShutdown(GcHeap **gcHeap) 637{ 638 assert(gcHeap != NULL); 639 if (*gcHeap != NULL && (*gcHeap)->heapSource != NULL) { 640 HeapSource *hs = (*gcHeap)->heapSource; 641 dvmHeapBitmapDelete(&hs->liveBits); 642 dvmHeapBitmapDelete(&hs->markBits); 643 freeMarkStack(&(*gcHeap)->markContext.stack); 644 munmap(hs->heapBase, hs->heapLength); 645 free(hs); 646 gHs = NULL; 647 free(*gcHeap); 648 *gcHeap = NULL; 649 } 650} 651 652/* 653 * Gets the begining of the allocation for the HeapSource. 654 */ 655void *dvmHeapSourceGetBase() 656{ 657 return gHs->heapBase; 658} 659 660/* 661 * Returns the requested value. If the per-heap stats are requested, fill 662 * them as well. 663 * 664 * Caller must hold the heap lock. 665 */ 666size_t dvmHeapSourceGetValue(HeapSourceValueSpec spec, size_t perHeapStats[], 667 size_t arrayLen) 668{ 669 HeapSource *hs = gHs; 670 size_t value = 0; 671 size_t total = 0; 672 673 HS_BOILERPLATE(); 674 675 assert(arrayLen >= hs->numHeaps || perHeapStats == NULL); 676 for (size_t i = 0; i < hs->numHeaps; i++) { 677 Heap *const heap = &hs->heaps[i]; 678 679 switch (spec) { 680 case HS_FOOTPRINT: 681 value = mspace_footprint(heap->msp); 682 break; 683 case HS_ALLOWED_FOOTPRINT: 684 value = mspace_max_allowed_footprint(heap->msp); 685 break; 686 case HS_BYTES_ALLOCATED: 687 value = heap->bytesAllocated; 688 break; 689 case HS_OBJECTS_ALLOCATED: 690 value = heap->objectsAllocated; 691 break; 692 default: 693 // quiet gcc 694 break; 695 } 696 if (perHeapStats) { 697 perHeapStats[i] = value; 698 } 699 total += value; 700 } 701 return total; 702} 703 704void dvmHeapSourceGetRegions(uintptr_t *base, uintptr_t *max, uintptr_t *limit, 705 size_t numHeaps) 706{ 707 HeapSource *hs = gHs; 708 709 HS_BOILERPLATE(); 710 711 assert(numHeaps <= hs->numHeaps); 712 for (size_t i = 0; i < numHeaps; ++i) { 713 base[i] = (uintptr_t)hs->heaps[i].base; 714 if (max != NULL) { 715 max[i] = MIN((uintptr_t)hs->heaps[i].limit - 1, hs->markBits.max); 716 } 717 if (limit != NULL) { 718 limit[i] = (uintptr_t)hs->heaps[i].limit; 719 } 720 } 721} 722 723/* 724 * Get the bitmap representing all live objects. 725 */ 726HeapBitmap *dvmHeapSourceGetLiveBits() 727{ 728 HS_BOILERPLATE(); 729 730 return &gHs->liveBits; 731} 732 733/* 734 * Get the bitmap representing all marked objects. 735 */ 736HeapBitmap *dvmHeapSourceGetMarkBits() 737{ 738 HS_BOILERPLATE(); 739 740 return &gHs->markBits; 741} 742 743void dvmHeapSourceSwapBitmaps() 744{ 745 HeapBitmap tmp = gHs->liveBits; 746 gHs->liveBits = gHs->markBits; 747 gHs->markBits = tmp; 748} 749 750void dvmHeapSourceZeroMarkBitmap() 751{ 752 HS_BOILERPLATE(); 753 754 dvmHeapBitmapZero(&gHs->markBits); 755} 756 757void dvmMarkImmuneObjects(const char *immuneLimit) 758{ 759 /* 760 * Copy the contents of the live bit vector for immune object 761 * range into the mark bit vector. 762 */ 763 /* The only values generated by dvmHeapSourceGetImmuneLimit() */ 764 assert(immuneLimit == gHs->heaps[0].base || 765 immuneLimit == NULL); 766 assert(gHs->liveBits.base == gHs->markBits.base); 767 assert(gHs->liveBits.bitsLen == gHs->markBits.bitsLen); 768 /* heap[0] is never immune */ 769 assert(gHs->heaps[0].base >= immuneLimit); 770 assert(gHs->heaps[0].limit > immuneLimit); 771 772 for (size_t i = 1; i < gHs->numHeaps; ++i) { 773 if (gHs->heaps[i].base < immuneLimit) { 774 assert(gHs->heaps[i].limit <= immuneLimit); 775 /* Compute the number of words to copy in the bitmap. */ 776 size_t index = HB_OFFSET_TO_INDEX( 777 (uintptr_t)gHs->heaps[i].base - gHs->liveBits.base); 778 /* Compute the starting offset in the live and mark bits. */ 779 char *src = (char *)(gHs->liveBits.bits + index); 780 char *dst = (char *)(gHs->markBits.bits + index); 781 /* Compute the number of bytes of the live bitmap to copy. */ 782 size_t length = HB_OFFSET_TO_BYTE_INDEX( 783 gHs->heaps[i].limit - gHs->heaps[i].base); 784 /* Do the copy. */ 785 memcpy(dst, src, length); 786 /* Make sure max points to the address of the highest set bit. */ 787 if (gHs->markBits.max < (uintptr_t)gHs->heaps[i].limit) { 788 gHs->markBits.max = (uintptr_t)gHs->heaps[i].limit; 789 } 790 } 791 } 792} 793 794/* 795 * Allocates <n> bytes of zeroed data. 796 */ 797void* dvmHeapSourceAlloc(size_t n) 798{ 799 HS_BOILERPLATE(); 800 801 HeapSource *hs = gHs; 802 Heap* heap = hs2heap(hs); 803 if (heap->bytesAllocated + n > hs->softLimit) { 804 /* 805 * This allocation would push us over the soft limit; act as 806 * if the heap is full. 807 */ 808 LOGV_HEAP("softLimit of %zd.%03zdMB hit for %zd-byte allocation", 809 FRACTIONAL_MB(hs->softLimit), n); 810 return NULL; 811 } 812 void* ptr = mspace_calloc(heap->msp, 1, n); 813 if (ptr == NULL) { 814 return NULL; 815 } 816 countAllocation(heap, ptr); 817 /* 818 * Check to see if a concurrent GC should be initiated. 819 */ 820 if (gDvm.gcHeap->gcRunning || !hs->hasGcThread) { 821 /* 822 * The garbage collector thread is already running or has yet 823 * to be started. Do nothing. 824 */ 825 return ptr; 826 } 827 if (heap->bytesAllocated > heap->concurrentStartBytes) { 828 /* 829 * We have exceeded the allocation threshold. Wake up the 830 * garbage collector. 831 */ 832 dvmSignalCond(&gHs->gcThreadCond); 833 } 834 return ptr; 835} 836 837/* Remove any hard limits, try to allocate, and shrink back down. 838 * Last resort when trying to allocate an object. 839 */ 840static void* heapAllocAndGrow(HeapSource *hs, Heap *heap, size_t n) 841{ 842 /* Grow as much as possible, but don't let the real footprint 843 * go over the absolute max. 844 */ 845 size_t max = heap->maximumSize; 846 847 mspace_set_max_allowed_footprint(heap->msp, max); 848 void* ptr = dvmHeapSourceAlloc(n); 849 850 /* Shrink back down as small as possible. Our caller may 851 * readjust max_allowed to a more appropriate value. 852 */ 853 mspace_set_max_allowed_footprint(heap->msp, 854 mspace_footprint(heap->msp)); 855 return ptr; 856} 857 858/* 859 * Allocates <n> bytes of zeroed data, growing as much as possible 860 * if necessary. 861 */ 862void* dvmHeapSourceAllocAndGrow(size_t n) 863{ 864 HS_BOILERPLATE(); 865 866 HeapSource *hs = gHs; 867 Heap* heap = hs2heap(hs); 868 void* ptr = dvmHeapSourceAlloc(n); 869 if (ptr != NULL) { 870 return ptr; 871 } 872 873 size_t oldIdealSize = hs->idealSize; 874 if (isSoftLimited(hs)) { 875 /* We're soft-limited. Try removing the soft limit to 876 * see if we can allocate without actually growing. 877 */ 878 hs->softLimit = SIZE_MAX; 879 ptr = dvmHeapSourceAlloc(n); 880 if (ptr != NULL) { 881 /* Removing the soft limit worked; fix things up to 882 * reflect the new effective ideal size. 883 */ 884 snapIdealFootprint(); 885 return ptr; 886 } 887 // softLimit intentionally left at SIZE_MAX. 888 } 889 890 /* We're not soft-limited. Grow the heap to satisfy the request. 891 * If this call fails, no footprints will have changed. 892 */ 893 ptr = heapAllocAndGrow(hs, heap, n); 894 if (ptr != NULL) { 895 /* The allocation succeeded. Fix up the ideal size to 896 * reflect any footprint modifications that had to happen. 897 */ 898 snapIdealFootprint(); 899 } else { 900 /* We just couldn't do it. Restore the original ideal size, 901 * fixing up softLimit if necessary. 902 */ 903 setIdealFootprint(oldIdealSize); 904 } 905 return ptr; 906} 907 908/* 909 * Frees the first numPtrs objects in the ptrs list and returns the 910 * amount of reclaimed storage. The list must contain addresses all in 911 * the same mspace, and must be in increasing order. This implies that 912 * there are no duplicates, and no entries are NULL. 913 */ 914size_t dvmHeapSourceFreeList(size_t numPtrs, void **ptrs) 915{ 916 HS_BOILERPLATE(); 917 918 if (numPtrs == 0) { 919 return 0; 920 } 921 922 assert(ptrs != NULL); 923 assert(*ptrs != NULL); 924 Heap* heap = ptr2heap(gHs, *ptrs); 925 size_t numBytes = 0; 926 if (heap != NULL) { 927 mspace msp = heap->msp; 928 // Calling mspace_free on shared heaps disrupts sharing too 929 // much. For heap[0] -- the 'active heap' -- we call 930 // mspace_free, but on the other heaps we only do some 931 // accounting. 932 if (heap == gHs->heaps) { 933 // mspace_merge_objects takes two allocated objects, and 934 // if the second immediately follows the first, will merge 935 // them, returning a larger object occupying the same 936 // memory. This is a local operation, and doesn't require 937 // dlmalloc to manipulate any freelists. It's pretty 938 // inexpensive compared to free(). 939 940 // ptrs is an array of objects all in memory order, and if 941 // client code has been allocating lots of short-lived 942 // objects, this is likely to contain runs of objects all 943 // now garbage, and thus highly amenable to this optimization. 944 945 // Unroll the 0th iteration around the loop below, 946 // countFree ptrs[0] and initializing merged. 947 assert(ptrs[0] != NULL); 948 assert(ptr2heap(gHs, ptrs[0]) == heap); 949 countFree(heap, ptrs[0], &numBytes); 950 void *merged = ptrs[0]; 951 for (size_t i = 1; i < numPtrs; i++) { 952 assert(merged != NULL); 953 assert(ptrs[i] != NULL); 954 assert((intptr_t)merged < (intptr_t)ptrs[i]); 955 assert(ptr2heap(gHs, ptrs[i]) == heap); 956 countFree(heap, ptrs[i], &numBytes); 957 // Try to merge. If it works, merged now includes the 958 // memory of ptrs[i]. If it doesn't, free merged, and 959 // see if ptrs[i] starts a new run of adjacent 960 // objects to merge. 961 if (mspace_merge_objects(msp, merged, ptrs[i]) == NULL) { 962 mspace_free(msp, merged); 963 merged = ptrs[i]; 964 } 965 } 966 assert(merged != NULL); 967 mspace_free(msp, merged); 968 } else { 969 // This is not an 'active heap'. Only do the accounting. 970 for (size_t i = 0; i < numPtrs; i++) { 971 assert(ptrs[i] != NULL); 972 assert(ptr2heap(gHs, ptrs[i]) == heap); 973 countFree(heap, ptrs[i], &numBytes); 974 } 975 } 976 } 977 return numBytes; 978} 979 980/* 981 * Returns true iff <ptr> is in the heap source. 982 */ 983bool dvmHeapSourceContainsAddress(const void *ptr) 984{ 985 HS_BOILERPLATE(); 986 987 return (dvmHeapBitmapCoversAddress(&gHs->liveBits, ptr)); 988} 989 990/* 991 * Returns true iff <ptr> was allocated from the heap source. 992 */ 993bool dvmHeapSourceContains(const void *ptr) 994{ 995 HS_BOILERPLATE(); 996 997 if (dvmHeapSourceContainsAddress(ptr)) { 998 return dvmHeapBitmapIsObjectBitSet(&gHs->liveBits, ptr) != 0; 999 } 1000 return false; 1001} 1002 1003bool dvmIsZygoteObject(const Object* obj) 1004{ 1005 HeapSource *hs = gHs; 1006 1007 HS_BOILERPLATE(); 1008 1009 if (dvmHeapSourceContains(obj) && hs->sawZygote) { 1010 Heap *heap = ptr2heap(hs, obj); 1011 if (heap != NULL) { 1012 /* If the object is not in the active heap, we assume that 1013 * it was allocated as part of zygote. 1014 */ 1015 return heap != hs->heaps; 1016 } 1017 } 1018 /* The pointer is outside of any known heap, or we are not 1019 * running in zygote mode. 1020 */ 1021 return false; 1022} 1023 1024/* 1025 * Returns the number of usable bytes in an allocated chunk; the size 1026 * may be larger than the size passed to dvmHeapSourceAlloc(). 1027 */ 1028size_t dvmHeapSourceChunkSize(const void *ptr) 1029{ 1030 HS_BOILERPLATE(); 1031 1032 Heap* heap = ptr2heap(gHs, ptr); 1033 if (heap != NULL) { 1034 return mspace_usable_size(heap->msp, ptr); 1035 } 1036 return 0; 1037} 1038 1039/* 1040 * Returns the number of bytes that the heap source has allocated 1041 * from the system using sbrk/mmap, etc. 1042 * 1043 * Caller must hold the heap lock. 1044 */ 1045size_t dvmHeapSourceFootprint() 1046{ 1047 HS_BOILERPLATE(); 1048 1049//TODO: include size of bitmaps? 1050 return oldHeapOverhead(gHs, true); 1051} 1052 1053static size_t getMaximumSize(const HeapSource *hs) 1054{ 1055 return hs->growthLimit; 1056} 1057 1058/* 1059 * Returns the current maximum size of the heap source respecting any 1060 * growth limits. 1061 */ 1062size_t dvmHeapSourceGetMaximumSize() 1063{ 1064 HS_BOILERPLATE(); 1065 return getMaximumSize(gHs); 1066} 1067 1068/* 1069 * Removes any growth limits. Allows the user to allocate up to the 1070 * maximum heap size. 1071 */ 1072void dvmClearGrowthLimit() 1073{ 1074 HS_BOILERPLATE(); 1075 dvmLockHeap(); 1076 dvmWaitForConcurrentGcToComplete(); 1077 gHs->growthLimit = gHs->maximumSize; 1078 size_t overhead = oldHeapOverhead(gHs, false); 1079 gHs->heaps[0].maximumSize = gHs->maximumSize - overhead; 1080 gHs->heaps[0].limit = gHs->heaps[0].base + gHs->heaps[0].maximumSize; 1081 dvmUnlockHeap(); 1082} 1083 1084/* 1085 * Return the real bytes used by old heaps plus the soft usage of the 1086 * current heap. When a soft limit is in effect, this is effectively 1087 * what it's compared against (though, in practice, it only looks at 1088 * the current heap). 1089 */ 1090static size_t getSoftFootprint(bool includeActive) 1091{ 1092 HS_BOILERPLATE(); 1093 1094 HeapSource *hs = gHs; 1095 size_t ret = oldHeapOverhead(hs, false); 1096 if (includeActive) { 1097 ret += hs->heaps[0].bytesAllocated; 1098 } 1099 1100 return ret; 1101} 1102 1103/* 1104 * Gets the maximum number of bytes that the heap source is allowed 1105 * to allocate from the system. 1106 */ 1107size_t dvmHeapSourceGetIdealFootprint() 1108{ 1109 HeapSource *hs = gHs; 1110 1111 HS_BOILERPLATE(); 1112 1113 return hs->idealSize; 1114} 1115 1116/* 1117 * Sets the soft limit, handling any necessary changes to the allowed 1118 * footprint of the active heap. 1119 */ 1120static void setSoftLimit(HeapSource *hs, size_t softLimit) 1121{ 1122 /* Compare against the actual footprint, rather than the 1123 * max_allowed, because the heap may not have grown all the 1124 * way to the allowed size yet. 1125 */ 1126 mspace msp = hs->heaps[0].msp; 1127 size_t currentHeapSize = mspace_footprint(msp); 1128 if (softLimit < currentHeapSize) { 1129 /* Don't let the heap grow any more, and impose a soft limit. 1130 */ 1131 mspace_set_max_allowed_footprint(msp, currentHeapSize); 1132 hs->softLimit = softLimit; 1133 } else { 1134 /* Let the heap grow to the requested max, and remove any 1135 * soft limit, if set. 1136 */ 1137 mspace_set_max_allowed_footprint(msp, softLimit); 1138 hs->softLimit = SIZE_MAX; 1139 } 1140} 1141 1142/* 1143 * Sets the maximum number of bytes that the heap source is allowed 1144 * to allocate from the system. Clamps to the appropriate maximum 1145 * value. 1146 */ 1147static void setIdealFootprint(size_t max) 1148{ 1149 HS_BOILERPLATE(); 1150 1151 HeapSource *hs = gHs; 1152 size_t maximumSize = getMaximumSize(hs); 1153 if (max > maximumSize) { 1154 LOGI_HEAP("Clamp target GC heap from %zd.%03zdMB to %u.%03uMB", 1155 FRACTIONAL_MB(max), 1156 FRACTIONAL_MB(maximumSize)); 1157 max = maximumSize; 1158 } 1159 1160 /* Convert max into a size that applies to the active heap. 1161 * Old heaps will count against the ideal size. 1162 */ 1163 size_t overhead = getSoftFootprint(false); 1164 size_t activeMax; 1165 if (overhead < max) { 1166 activeMax = max - overhead; 1167 } else { 1168 activeMax = 0; 1169 } 1170 1171 setSoftLimit(hs, activeMax); 1172 hs->idealSize = max; 1173} 1174 1175/* 1176 * Make the ideal footprint equal to the current footprint. 1177 */ 1178static void snapIdealFootprint() 1179{ 1180 HS_BOILERPLATE(); 1181 1182 setIdealFootprint(getSoftFootprint(true)); 1183} 1184 1185/* 1186 * Gets the current ideal heap utilization, represented as a number 1187 * between zero and one. 1188 */ 1189float dvmGetTargetHeapUtilization() 1190{ 1191 HeapSource *hs = gHs; 1192 1193 HS_BOILERPLATE(); 1194 1195 return (float)hs->targetUtilization / (float)HEAP_UTILIZATION_MAX; 1196} 1197 1198/* 1199 * Sets the new ideal heap utilization, represented as a number 1200 * between zero and one. 1201 */ 1202void dvmSetTargetHeapUtilization(float newTarget) 1203{ 1204 HeapSource *hs = gHs; 1205 1206 HS_BOILERPLATE(); 1207 1208 /* Clamp it to a reasonable range. 1209 */ 1210 // TODO: This may need some tuning. 1211 if (newTarget < 0.2) { 1212 newTarget = 0.2; 1213 } else if (newTarget > 0.8) { 1214 newTarget = 0.8; 1215 } 1216 1217 hs->targetUtilization = 1218 (size_t)(newTarget * (float)HEAP_UTILIZATION_MAX); 1219 LOGV("Set heap target utilization to %zd/%d (%f)", 1220 hs->targetUtilization, HEAP_UTILIZATION_MAX, newTarget); 1221} 1222 1223/* 1224 * Given the size of a live set, returns the ideal heap size given 1225 * the current target utilization and MIN/MAX values. 1226 * 1227 * targetUtilization is in the range 1..HEAP_UTILIZATION_MAX. 1228 */ 1229static size_t getUtilizationTarget(size_t liveSize, size_t targetUtilization) 1230{ 1231 /* Use the current target utilization ratio to determine the 1232 * ideal heap size based on the size of the live set. 1233 */ 1234 size_t targetSize = (liveSize / targetUtilization) * HEAP_UTILIZATION_MAX; 1235 1236 /* Cap the amount of free space, though, so we don't end up 1237 * with, e.g., 8MB of free space when the live set size hits 8MB. 1238 */ 1239 if (targetSize > liveSize + HEAP_IDEAL_FREE) { 1240 targetSize = liveSize + HEAP_IDEAL_FREE; 1241 } else if (targetSize < liveSize + HEAP_MIN_FREE) { 1242 targetSize = liveSize + HEAP_MIN_FREE; 1243 } 1244 return targetSize; 1245} 1246 1247/* 1248 * Given the current contents of the active heap, increase the allowed 1249 * heap footprint to match the target utilization ratio. This 1250 * should only be called immediately after a full mark/sweep. 1251 */ 1252void dvmHeapSourceGrowForUtilization() 1253{ 1254 HS_BOILERPLATE(); 1255 1256 HeapSource *hs = gHs; 1257 Heap* heap = hs2heap(hs); 1258 1259 /* Use the current target utilization ratio to determine the 1260 * ideal heap size based on the size of the live set. 1261 * Note that only the active heap plays any part in this. 1262 * 1263 * Avoid letting the old heaps influence the target free size, 1264 * because they may be full of objects that aren't actually 1265 * in the working set. Just look at the allocated size of 1266 * the current heap. 1267 */ 1268 size_t currentHeapUsed = heap->bytesAllocated; 1269 size_t targetHeapSize = 1270 getUtilizationTarget(currentHeapUsed, hs->targetUtilization); 1271 1272 /* The ideal size includes the old heaps; add overhead so that 1273 * it can be immediately subtracted again in setIdealFootprint(). 1274 * If the target heap size would exceed the max, setIdealFootprint() 1275 * will clamp it to a legal value. 1276 */ 1277 size_t overhead = getSoftFootprint(false); 1278 setIdealFootprint(targetHeapSize + overhead); 1279 1280 size_t freeBytes = getAllocLimit(hs); 1281 if (freeBytes < CONCURRENT_MIN_FREE) { 1282 /* Not enough free memory to allow a concurrent GC. */ 1283 heap->concurrentStartBytes = SIZE_MAX; 1284 } else { 1285 heap->concurrentStartBytes = freeBytes - CONCURRENT_START; 1286 } 1287} 1288 1289/* 1290 * Return free pages to the system. 1291 * TODO: move this somewhere else, especially the native heap part. 1292 */ 1293static void releasePagesInRange(void *start, void *end, void *nbytes) 1294{ 1295 /* Linux requires that the madvise() start address is page-aligned. 1296 * We also align the end address. 1297 */ 1298 start = (void *)ALIGN_UP_TO_PAGE_SIZE(start); 1299 end = (void *)((size_t)end & ~(SYSTEM_PAGE_SIZE - 1)); 1300 if (start < end) { 1301 size_t length = (char *)end - (char *)start; 1302 madvise(start, length, MADV_DONTNEED); 1303 *(size_t *)nbytes += length; 1304 } 1305} 1306 1307/* 1308 * Return unused memory to the system if possible. 1309 */ 1310static void trimHeaps() 1311{ 1312 HS_BOILERPLATE(); 1313 1314 HeapSource *hs = gHs; 1315 size_t heapBytes = 0; 1316 for (size_t i = 0; i < hs->numHeaps; i++) { 1317 Heap *heap = &hs->heaps[i]; 1318 1319 /* Return the wilderness chunk to the system. 1320 */ 1321 mspace_trim(heap->msp, 0); 1322 1323 /* Return any whole free pages to the system. 1324 */ 1325 mspace_walk_free_pages(heap->msp, releasePagesInRange, &heapBytes); 1326 } 1327 1328 /* Same for the native heap. 1329 */ 1330 dlmalloc_trim(0); 1331 size_t nativeBytes = 0; 1332 dlmalloc_walk_free_pages(releasePagesInRange, &nativeBytes); 1333 1334 LOGD_HEAP("madvised %zd (GC) + %zd (native) = %zd total bytes", 1335 heapBytes, nativeBytes, heapBytes + nativeBytes); 1336} 1337 1338/* 1339 * Walks over the heap source and passes every allocated and 1340 * free chunk to the callback. 1341 */ 1342void dvmHeapSourceWalk(void(*callback)(const void *chunkptr, size_t chunklen, 1343 const void *userptr, size_t userlen, 1344 void *arg), 1345 void *arg) 1346{ 1347 HS_BOILERPLATE(); 1348 1349 /* Walk the heaps from oldest to newest. 1350 */ 1351//TODO: do this in address order 1352 HeapSource *hs = gHs; 1353 for (size_t i = hs->numHeaps; i > 0; --i) { 1354 mspace_walk_heap(hs->heaps[i-1].msp, callback, arg); 1355 } 1356} 1357 1358/* 1359 * Gets the number of heaps available in the heap source. 1360 * 1361 * Caller must hold the heap lock, because gHs caches a field 1362 * in gDvm.gcHeap. 1363 */ 1364size_t dvmHeapSourceGetNumHeaps() 1365{ 1366 HS_BOILERPLATE(); 1367 1368 return gHs->numHeaps; 1369} 1370 1371void *dvmHeapSourceGetImmuneLimit(bool isPartial) 1372{ 1373 if (isPartial) { 1374 return hs2heap(gHs)->base; 1375 } else { 1376 return NULL; 1377 } 1378} 1379