1 /* 2 * Copyright (c) 2015, 2020, 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 #include "precompiled.hpp" 25 #include "gc/z/zArray.inline.hpp" 26 #include "gc/z/zErrno.hpp" 27 #include "gc/z/zGlobals.hpp" 28 #include "gc/z/zLargePages.inline.hpp" 29 #include "gc/z/zMountPoint_linux.hpp" 30 #include "gc/z/zNUMA.inline.hpp" 31 #include "gc/z/zPhysicalMemoryBacking_linux.hpp" 32 #include "gc/z/zSyscall_linux.hpp" 33 #include "logging/log.hpp" 34 #include "runtime/init.hpp" 35 #include "runtime/os.hpp" 36 #include "utilities/align.hpp" 37 #include "utilities/debug.hpp" 38 #include "utilities/growableArray.hpp" 39 40 #include <fcntl.h> 41 #include <stdio.h> 42 #include <sys/mman.h> 43 #include <sys/stat.h> 44 #include <sys/statfs.h> 45 #include <sys/types.h> 46 #include <unistd.h> 47 48 // 49 // Support for building on older Linux systems 50 // 51 52 // memfd_create(2) flags 53 #ifndef MFD_CLOEXEC 54 #define MFD_CLOEXEC 0x0001U 55 #endif 56 #ifndef MFD_HUGETLB 57 #define MFD_HUGETLB 0x0004U 58 #endif 59 60 // open(2) flags 61 #ifndef O_CLOEXEC 62 #define O_CLOEXEC 02000000 63 #endif 64 #ifndef O_TMPFILE 65 #define O_TMPFILE (020000000 | O_DIRECTORY) 66 #endif 67 68 // fallocate(2) flags 69 #ifndef FALLOC_FL_KEEP_SIZE 70 #define FALLOC_FL_KEEP_SIZE 0x01 71 #endif 72 #ifndef FALLOC_FL_PUNCH_HOLE 73 #define FALLOC_FL_PUNCH_HOLE 0x02 74 #endif 75 76 // Filesystem types, see statfs(2) 77 #ifndef TMPFS_MAGIC 78 #define TMPFS_MAGIC 0x01021994 79 #endif 80 #ifndef HUGETLBFS_MAGIC 81 #define HUGETLBFS_MAGIC 0x958458f6 82 #endif 83 84 // Filesystem names 85 #define ZFILESYSTEM_TMPFS "tmpfs" 86 #define ZFILESYSTEM_HUGETLBFS "hugetlbfs" 87 88 // Proc file entry for max map mount 89 #define ZFILENAME_PROC_MAX_MAP_COUNT "/proc/sys/vm/max_map_count" 90 91 // Sysfs file for transparent huge page on tmpfs 92 #define ZFILENAME_SHMEM_ENABLED "/sys/kernel/mm/transparent_hugepage/shmem_enabled" 93 94 // Java heap filename 95 #define ZFILENAME_HEAP "java_heap" 96 97 // Preferred tmpfs mount points, ordered by priority 98 static const char* z_preferred_tmpfs_mountpoints[] = { 99 "/dev/shm", 100 "/run/shm", 101 NULL 102 }; 103 104 // Preferred hugetlbfs mount points, ordered by priority 105 static const char* z_preferred_hugetlbfs_mountpoints[] = { 106 "/dev/hugepages", 107 "/hugepages", 108 NULL 109 }; 110 111 static int z_fallocate_hugetlbfs_attempts = 3; 112 static bool z_fallocate_supported = true; 113 114 ZPhysicalMemoryBacking::ZPhysicalMemoryBacking() : 115 _fd(-1), 116 _size(0), 117 _filesystem(0), 118 _block_size(0), 119 _available(0), 120 _initialized(false) { 121 122 // Create backing file 123 _fd = create_fd(ZFILENAME_HEAP); 124 if (_fd == -1) { 125 return; 126 } 127 128 // Get filesystem statistics 129 struct statfs buf; 130 if (fstatfs(_fd, &buf) == -1) { 131 ZErrno err; 132 log_error(gc)("Failed to determine filesystem type for backing file (%s)", err.to_string()); 133 return; 134 } 135 136 _filesystem = buf.f_type; 137 _block_size = buf.f_bsize; 138 _available = buf.f_bavail * _block_size; 139 140 // Make sure we're on a supported filesystem 141 if (!is_tmpfs() && !is_hugetlbfs()) { 142 log_error(gc)("Backing file must be located on a %s or a %s filesystem", 143 ZFILESYSTEM_TMPFS, ZFILESYSTEM_HUGETLBFS); 144 return; 145 } 146 147 // Make sure the filesystem type matches requested large page type 148 if (ZLargePages::is_transparent() && !is_tmpfs()) { 149 log_error(gc)("-XX:+UseTransparentHugePages can only be enable when using a %s filesystem", 150 ZFILESYSTEM_TMPFS); 151 return; 152 } 153 154 if (ZLargePages::is_transparent() && !tmpfs_supports_transparent_huge_pages()) { 155 log_error(gc)("-XX:+UseTransparentHugePages on a %s filesystem not supported by kernel", 156 ZFILESYSTEM_TMPFS); 157 return; 158 } 159 160 if (ZLargePages::is_explicit() && !is_hugetlbfs()) { 161 log_error(gc)("-XX:+UseLargePages (without -XX:+UseTransparentHugePages) can only be enabled " 162 "when using a %s filesystem", ZFILESYSTEM_HUGETLBFS); 163 return; 164 } 165 166 if (!ZLargePages::is_explicit() && is_hugetlbfs()) { 167 log_error(gc)("-XX:+UseLargePages must be enabled when using a %s filesystem", 168 ZFILESYSTEM_HUGETLBFS); 169 return; 170 } 171 172 const size_t expected_block_size = is_tmpfs() ? os::vm_page_size() : os::large_page_size(); 173 if (expected_block_size != _block_size) { 174 log_error(gc)("%s filesystem has unexpected block size " SIZE_FORMAT " (expected " SIZE_FORMAT ")", 175 is_tmpfs() ? ZFILESYSTEM_TMPFS : ZFILESYSTEM_HUGETLBFS, _block_size, expected_block_size); 176 return; 177 } 178 179 // Successfully initialized 180 _initialized = true; 181 } 182 183 int ZPhysicalMemoryBacking::create_mem_fd(const char* name) const { 184 // Create file name 185 char filename[PATH_MAX]; 186 snprintf(filename, sizeof(filename), "%s%s", name, ZLargePages::is_explicit() ? ".hugetlb" : ""); 187 188 // Create file 189 const int extra_flags = ZLargePages::is_explicit() ? MFD_HUGETLB : 0; 190 const int fd = ZSyscall::memfd_create(filename, MFD_CLOEXEC | extra_flags); 191 if (fd == -1) { 192 ZErrno err; 193 log_debug(gc, init)("Failed to create memfd file (%s)", 194 ((ZLargePages::is_explicit() && err == EINVAL) ? "Hugepages not supported" : err.to_string())); 195 return -1; 196 } 197 198 log_info(gc, init)("Heap backed by file: /memfd:%s", filename); 199 200 return fd; 201 } 202 203 int ZPhysicalMemoryBacking::create_file_fd(const char* name) const { 204 const char* const filesystem = ZLargePages::is_explicit() 205 ? ZFILESYSTEM_HUGETLBFS 206 : ZFILESYSTEM_TMPFS; 207 const char** const preferred_mountpoints = ZLargePages::is_explicit() 208 ? z_preferred_hugetlbfs_mountpoints 209 : z_preferred_tmpfs_mountpoints; 210 211 // Find mountpoint 212 ZMountPoint mountpoint(filesystem, preferred_mountpoints); 213 if (mountpoint.get() == NULL) { 214 log_error(gc)("Use -XX:AllocateHeapAt to specify the path to a %s filesystem", filesystem); 215 return -1; 216 } 217 218 // Try to create an anonymous file using the O_TMPFILE flag. Note that this 219 // flag requires kernel >= 3.11. If this fails we fall back to open/unlink. 220 const int fd_anon = os::open(mountpoint.get(), O_TMPFILE|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR); 221 if (fd_anon == -1) { 222 ZErrno err; 223 log_debug(gc, init)("Failed to create anonymous file in %s (%s)", mountpoint.get(), 224 (err == EINVAL ? "Not supported" : err.to_string())); 225 } else { 226 // Get inode number for anonymous file 227 struct stat stat_buf; 228 if (fstat(fd_anon, &stat_buf) == -1) { 229 ZErrno err; 230 log_error(gc)("Failed to determine inode number for anonymous file (%s)", err.to_string()); 231 return -1; 232 } 233 234 log_info(gc, init)("Heap backed by file: %s/#" UINT64_FORMAT, mountpoint.get(), (uint64_t)stat_buf.st_ino); 235 236 return fd_anon; 237 } 238 239 log_debug(gc, init)("Falling back to open/unlink"); 240 241 // Create file name 242 char filename[PATH_MAX]; 243 snprintf(filename, sizeof(filename), "%s/%s.%d", mountpoint.get(), name, os::current_process_id()); 244 245 // Create file 246 const int fd = os::open(filename, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR); 247 if (fd == -1) { 248 ZErrno err; 249 log_error(gc)("Failed to create file %s (%s)", filename, err.to_string()); 250 return -1; 251 } 252 253 // Unlink file 254 if (unlink(filename) == -1) { 255 ZErrno err; 256 log_error(gc)("Failed to unlink file %s (%s)", filename, err.to_string()); 257 return -1; 258 } 259 260 log_info(gc, init)("Heap backed by file: %s", filename); 261 262 return fd; 263 } 264 265 int ZPhysicalMemoryBacking::create_fd(const char* name) const { 266 if (AllocateHeapAt == NULL) { 267 // If the path is not explicitly specified, then we first try to create a memfd file 268 // instead of looking for a tmpfd/hugetlbfs mount point. Note that memfd_create() might 269 // not be supported at all (requires kernel >= 3.17), or it might not support large 270 // pages (requires kernel >= 4.14). If memfd_create() fails, then we try to create a 271 // file on an accessible tmpfs or hugetlbfs mount point. 272 const int fd = create_mem_fd(name); 273 if (fd != -1) { 274 return fd; 275 } 276 277 log_debug(gc, init)("Falling back to searching for an accessible mount point"); 278 } 279 280 return create_file_fd(name); 281 } 282 283 bool ZPhysicalMemoryBacking::is_initialized() const { 284 return _initialized; 285 } 286 287 void ZPhysicalMemoryBacking::warn_available_space(size_t max) const { 288 // Note that the available space on a tmpfs or a hugetlbfs filesystem 289 // will be zero if no size limit was specified when it was mounted. 290 if (_available == 0) { 291 // No size limit set, skip check 292 log_info(gc, init)("Available space on backing filesystem: N/A"); 293 return; 294 } 295 296 log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", _available / M); 297 298 // Warn if the filesystem doesn't currently have enough space available to hold 299 // the max heap size. The max heap size will be capped if we later hit this limit 300 // when trying to expand the heap. 301 if (_available < max) { 302 log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****"); 303 log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap"); 304 log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly " 305 "(available", max / M); 306 log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem " 307 "size could", _available / M); 308 log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory."); 309 } 310 } 311 312 void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const { 313 const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT; 314 FILE* const file = fopen(filename, "r"); 315 if (file == NULL) { 316 // Failed to open file, skip check 317 log_debug(gc, init)("Failed to open %s", filename); 318 return; 319 } 320 321 size_t actual_max_map_count = 0; 322 const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count); 323 fclose(file); 324 if (result != 1) { 325 // Failed to read file, skip check 326 log_debug(gc, init)("Failed to read %s", filename); 327 return; 328 } 329 330 // The required max map count is impossible to calculate exactly since subsystems 331 // other than ZGC are also creating memory mappings, and we have no control over that. 332 // However, ZGC tends to create the most mappings and dominate the total count. 333 // In the worst cases, ZGC will map each granule three times, i.e. once per heap view. 334 // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory. 335 const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2; 336 if (actual_max_map_count < required_max_map_count) { 337 log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****"); 338 log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given"); 339 log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at", 340 max / M, filename); 341 log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution " 342 "with the current", required_max_map_count, actual_max_map_count); 343 log_warning(gc)("limit could lead to a fatal error, due to failure to map memory."); 344 } 345 } 346 347 void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const { 348 // Warn if available space is too low 349 warn_available_space(max); 350 351 // Warn if max map count is too low 352 warn_max_map_count(max); 353 } 354 355 size_t ZPhysicalMemoryBacking::size() const { 356 return _size; 357 } 358 359 bool ZPhysicalMemoryBacking::is_tmpfs() const { 360 return _filesystem == TMPFS_MAGIC; 361 } 362 363 bool ZPhysicalMemoryBacking::is_hugetlbfs() const { 364 return _filesystem == HUGETLBFS_MAGIC; 365 } 366 367 bool ZPhysicalMemoryBacking::tmpfs_supports_transparent_huge_pages() const { 368 // If the shmem_enabled file exists and is readable then we 369 // know the kernel supports transparent huge pages for tmpfs. 370 return access(ZFILENAME_SHMEM_ENABLED, R_OK) == 0; 371 } 372 373 ZErrno ZPhysicalMemoryBacking::fallocate_compat_ftruncate(size_t size) const { 374 while (ftruncate(_fd, size) == -1) { 375 if (errno != EINTR) { 376 // Failed 377 return errno; 378 } 379 } 380 381 // Success 382 return 0; 383 } 384 385 ZErrno ZPhysicalMemoryBacking::fallocate_compat_mmap(size_t offset, size_t length, bool touch) const { 386 // On hugetlbfs, mapping a file segment will fail immediately, without 387 // the need to touch the mapped pages first, if there aren't enough huge 388 // pages available to back the mapping. 389 void* const addr = mmap(0, length, PROT_READ|PROT_WRITE, MAP_SHARED, _fd, offset); 390 if (addr == MAP_FAILED) { 391 // Failed 392 return errno; 393 } 394 395 // Once mapped, the huge pages are only reserved. We need to touch them 396 // to associate them with the file segment. Note that we can not punch 397 // hole in file segments which only have reserved pages. 398 if (touch) { 399 char* const start = (char*)addr; 400 char* const end = start + length; 401 os::pretouch_memory(start, end, _block_size); 402 } 403 404 // Unmap again. From now on, the huge pages that were mapped are allocated 405 // to this file. There's no risk in getting SIGBUS when touching them. 406 if (munmap(addr, length) == -1) { 407 // Failed 408 return errno; 409 } 410 411 // Success 412 return 0; 413 } 414 415 ZErrno ZPhysicalMemoryBacking::fallocate_compat_pwrite(size_t offset, size_t length) const { 416 uint8_t data = 0; 417 418 // Allocate backing memory by writing to each block 419 for (size_t pos = offset; pos < offset + length; pos += _block_size) { 420 if (pwrite(_fd, &data, sizeof(data), pos) == -1) { 421 // Failed 422 return errno; 423 } 424 } 425 426 // Success 427 return 0; 428 } 429 430 ZErrno ZPhysicalMemoryBacking::fallocate_fill_hole_compat(size_t offset, size_t length) { 431 // fallocate(2) is only supported by tmpfs since Linux 3.5, and by hugetlbfs 432 // since Linux 4.3. When fallocate(2) is not supported we emulate it using 433 // ftruncate/pwrite (for tmpfs) or ftruncate/mmap/munmap (for hugetlbfs). 434 435 const size_t end = offset + length; 436 if (end > _size) { 437 // Increase file size 438 const ZErrno err = fallocate_compat_ftruncate(end); 439 if (err) { 440 // Failed 441 return err; 442 } 443 } 444 445 // Allocate backing memory 446 const ZErrno err = is_hugetlbfs() ? fallocate_compat_mmap(offset, length, false /* touch */) 447 : fallocate_compat_pwrite(offset, length); 448 if (err) { 449 if (end > _size) { 450 // Restore file size 451 fallocate_compat_ftruncate(_size); 452 } 453 454 // Failed 455 return err; 456 } 457 458 if (end > _size) { 459 // Record new file size 460 _size = end; 461 } 462 463 // Success 464 return 0; 465 } 466 467 ZErrno ZPhysicalMemoryBacking::fallocate_fill_hole_syscall(size_t offset, size_t length) { 468 const int mode = 0; // Allocate 469 const int res = ZSyscall::fallocate(_fd, mode, offset, length); 470 if (res == -1) { 471 // Failed 472 return errno; 473 } 474 475 const size_t end = offset + length; 476 if (end > _size) { 477 // Record new file size 478 _size = end; 479 } 480 481 // Success 482 return 0; 483 } 484 485 ZErrno ZPhysicalMemoryBacking::fallocate_fill_hole(size_t offset, size_t length) { 486 // Using compat mode is more efficient when allocating space on hugetlbfs. 487 // Note that allocating huge pages this way will only reserve them, and not 488 // associate them with segments of the file. We must guarantee that we at 489 // some point touch these segments, otherwise we can not punch hole in them. 490 if (z_fallocate_supported && !is_hugetlbfs()) { 491 const ZErrno err = fallocate_fill_hole_syscall(offset, length); 492 if (!err) { 493 // Success 494 return 0; 495 } 496 497 if (err != ENOSYS && err != EOPNOTSUPP) { 498 // Failed 499 return err; 500 } 501 502 // Not supported 503 log_debug(gc)("Falling back to fallocate() compatibility mode"); 504 z_fallocate_supported = false; 505 } 506 507 return fallocate_fill_hole_compat(offset, length); 508 } 509 510 ZErrno ZPhysicalMemoryBacking::fallocate_punch_hole(size_t offset, size_t length) { 511 if (is_hugetlbfs()) { 512 // We can only punch hole in pages that have been touched. Non-touched 513 // pages are only reserved, and not associated with any specific file 514 // segment. We don't know which pages have been previously touched, so 515 // we always touch them here to guarantee that we can punch hole. 516 const ZErrno err = fallocate_compat_mmap(offset, length, true /* touch */); 517 if (err) { 518 // Failed 519 return err; 520 } 521 } 522 523 const int mode = FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE; 524 if (ZSyscall::fallocate(_fd, mode, offset, length) == -1) { 525 // Failed 526 return errno; 527 } 528 529 // Success 530 return 0; 531 } 532 533 ZErrno ZPhysicalMemoryBacking::split_and_fallocate(bool punch_hole, size_t offset, size_t length) { 534 // Try first half 535 const size_t offset0 = offset; 536 const size_t length0 = align_up(length / 2, _block_size); 537 const ZErrno err0 = fallocate(punch_hole, offset0, length0); 538 if (err0) { 539 return err0; 540 } 541 542 // Try second half 543 const size_t offset1 = offset0 + length0; 544 const size_t length1 = length - length0; 545 const ZErrno err1 = fallocate(punch_hole, offset1, length1); 546 if (err1) { 547 return err1; 548 } 549 550 // Success 551 return 0; 552 } 553 554 ZErrno ZPhysicalMemoryBacking::fallocate(bool punch_hole, size_t offset, size_t length) { 555 assert(is_aligned(offset, _block_size), "Invalid offset"); 556 assert(is_aligned(length, _block_size), "Invalid length"); 557 558 const ZErrno err = punch_hole ? fallocate_punch_hole(offset, length) : fallocate_fill_hole(offset, length); 559 if (err == EINTR && length > _block_size) { 560 // Calling fallocate(2) with a large length can take a long time to 561 // complete. When running profilers, such as VTune, this syscall will 562 // be constantly interrupted by signals. Expanding the file in smaller 563 // steps avoids this problem. 564 return split_and_fallocate(punch_hole, offset, length); 565 } 566 567 return err; 568 } 569 570 bool ZPhysicalMemoryBacking::commit_inner(size_t offset, size_t length) { 571 log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)", 572 offset / M, (offset + length) / M, length / M); 573 574 retry: 575 const ZErrno err = fallocate(false /* punch_hole */, offset, length); 576 if (err) { 577 if (err == ENOSPC && !is_init_completed() && is_hugetlbfs() && z_fallocate_hugetlbfs_attempts-- > 0) { 578 // If we fail to allocate during initialization, due to lack of space on 579 // the hugetlbfs filesystem, then we wait and retry a few times before 580 // giving up. Otherwise there is a risk that running JVMs back-to-back 581 // will fail, since there is a delay between process termination and the 582 // huge pages owned by that process being returned to the huge page pool 583 // and made available for new allocations. 584 log_debug(gc, init)("Failed to commit memory (%s), retrying", err.to_string()); 585 586 // Wait and retry in one second, in the hope that huge pages will be 587 // available by then. 588 sleep(1); 589 goto retry; 590 } 591 592 // Failed 593 log_error(gc)("Failed to commit memory (%s)", err.to_string()); 594 return false; 595 } 596 597 // Success 598 return true; 599 } 600 601 static int offset_to_node(size_t offset) { 602 const GrowableArray<int>* mapping = os::Linux::numa_nindex_to_node(); 603 const size_t nindex = (offset >> ZGranuleSizeShift) % mapping->length(); 604 return mapping->at((int)nindex); 605 } 606 607 size_t ZPhysicalMemoryBacking::commit_numa_interleaved(size_t offset, size_t length) { 608 size_t committed = 0; 609 610 // Commit one granule at a time, so that each granule 611 // can be allocated from a different preferred node. 612 while (committed < length) { 613 const size_t granule_offset = offset + committed; 614 615 // Setup NUMA policy to allocate memory from a preferred node 616 os::Linux::numa_set_preferred(offset_to_node(granule_offset)); 617 618 if (!commit_inner(granule_offset, ZGranuleSize)) { 619 // Failed 620 break; 621 } 622 623 committed += ZGranuleSize; 624 } 625 626 // Restore NUMA policy 627 os::Linux::numa_set_preferred(-1); 628 629 return committed; 630 } 631 632 size_t ZPhysicalMemoryBacking::commit_default(size_t offset, size_t length) { 633 // Try to commit the whole region 634 if (commit_inner(offset, length)) { 635 // Success 636 return length; 637 } 638 639 // Failed, try to commit as much as possible 640 size_t start = offset; 641 size_t end = offset + length; 642 643 for (;;) { 644 length = align_down((end - start) / 2, ZGranuleSize); 645 if (length < ZGranuleSize) { 646 // Done, don't commit more 647 return start - offset; 648 } 649 650 if (commit_inner(start, length)) { 651 // Success, try commit more 652 start += length; 653 } else { 654 // Failed, try commit less 655 end -= length; 656 } 657 } 658 } 659 660 size_t ZPhysicalMemoryBacking::commit(size_t offset, size_t length) { 661 if (ZNUMA::is_enabled() && !ZLargePages::is_explicit()) { 662 // To get granule-level NUMA interleaving when using non-large pages, 663 // we must explicitly interleave the memory at commit/fallocate time. 664 return commit_numa_interleaved(offset, length); 665 } 666 667 return commit_default(offset, length); 668 } 669 670 size_t ZPhysicalMemoryBacking::uncommit(size_t offset, size_t length) { 671 log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)", 672 offset / M, (offset + length) / M, length / M); 673 674 const ZErrno err = fallocate(true /* punch_hole */, offset, length); 675 if (err) { 676 log_error(gc)("Failed to uncommit memory (%s)", err.to_string()); 677 return 0; 678 } 679 680 return length; 681 } 682 683 void ZPhysicalMemoryBacking::map(uintptr_t addr, size_t size, uintptr_t offset) const { 684 const void* const res = mmap((void*)addr, size, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _fd, offset); 685 if (res == MAP_FAILED) { 686 ZErrno err; 687 fatal("Failed to map memory (%s)", err.to_string()); 688 } 689 } 690 691 void ZPhysicalMemoryBacking::unmap(uintptr_t addr, size_t size) const { 692 // Note that we must keep the address space reservation intact and just detach 693 // the backing memory. For this reason we map a new anonymous, non-accessible 694 // and non-reserved page over the mapping instead of actually unmapping. 695 const void* const res = mmap((void*)addr, size, PROT_NONE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, -1, 0); 696 if (res == MAP_FAILED) { 697 ZErrno err; 698 fatal("Failed to map memory (%s)", err.to_string()); 699 } 700 }