1config SELECT_MEMORY_MODEL 2 def_bool y 3 depends on ARCH_SELECT_MEMORY_MODEL 4 5choice 6 prompt "Memory model" 7 depends on SELECT_MEMORY_MODEL 8 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT 9 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 10 default FLATMEM_MANUAL 11 12config FLATMEM_MANUAL 13 bool "Flat Memory" 14 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE 15 help 16 This option allows you to change some of the ways that 17 Linux manages its memory internally. Most users will 18 only have one option here: FLATMEM. This is normal 19 and a correct option. 20 21 Some users of more advanced features like NUMA and 22 memory hotplug may have different options here. 23 DISCONTIGMEM is a more mature, better tested system, 24 but is incompatible with memory hotplug and may suffer 25 decreased performance over SPARSEMEM. If unsure between 26 "Sparse Memory" and "Discontiguous Memory", choose 27 "Discontiguous Memory". 28 29 If unsure, choose this option (Flat Memory) over any other. 30 31config DISCONTIGMEM_MANUAL 32 bool "Discontiguous Memory" 33 depends on ARCH_DISCONTIGMEM_ENABLE 34 help 35 This option provides enhanced support for discontiguous 36 memory systems, over FLATMEM. These systems have holes 37 in their physical address spaces, and this option provides 38 more efficient handling of these holes. However, the vast 39 majority of hardware has quite flat address spaces, and 40 can have degraded performance from the extra overhead that 41 this option imposes. 42 43 Many NUMA configurations will have this as the only option. 44 45 If unsure, choose "Flat Memory" over this option. 46 47config SPARSEMEM_MANUAL 48 bool "Sparse Memory" 49 depends on ARCH_SPARSEMEM_ENABLE 50 help 51 This will be the only option for some systems, including 52 memory hotplug systems. This is normal. 53 54 For many other systems, this will be an alternative to 55 "Discontiguous Memory". This option provides some potential 56 performance benefits, along with decreased code complexity, 57 but it is newer, and more experimental. 58 59 If unsure, choose "Discontiguous Memory" or "Flat Memory" 60 over this option. 61 62endchoice 63 64config DISCONTIGMEM 65 def_bool y 66 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL 67 68config SPARSEMEM 69 def_bool y 70 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL 71 72config FLATMEM 73 def_bool y 74 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL 75 76config FLAT_NODE_MEM_MAP 77 def_bool y 78 depends on !SPARSEMEM 79 80# 81# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's 82# to represent different areas of memory. This variable allows 83# those dependencies to exist individually. 84# 85config NEED_MULTIPLE_NODES 86 def_bool y 87 depends on DISCONTIGMEM || NUMA 88 89config HAVE_MEMORY_PRESENT 90 def_bool y 91 depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM 92 93# 94# SPARSEMEM_EXTREME (which is the default) does some bootmem 95# allocations when memory_present() is called. If this cannot 96# be done on your architecture, select this option. However, 97# statically allocating the mem_section[] array can potentially 98# consume vast quantities of .bss, so be careful. 99# 100# This option will also potentially produce smaller runtime code 101# with gcc 3.4 and later. 102# 103config SPARSEMEM_STATIC 104 bool 105 106# 107# Architecture platforms which require a two level mem_section in SPARSEMEM 108# must select this option. This is usually for architecture platforms with 109# an extremely sparse physical address space. 110# 111config SPARSEMEM_EXTREME 112 def_bool y 113 depends on SPARSEMEM && !SPARSEMEM_STATIC 114 115config SPARSEMEM_VMEMMAP_ENABLE 116 bool 117 118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER 119 def_bool y 120 depends on SPARSEMEM && X86_64 121 122config SPARSEMEM_VMEMMAP 123 bool "Sparse Memory virtual memmap" 124 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 125 default y 126 help 127 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 128 pfn_to_page and page_to_pfn operations. This is the most 129 efficient option when sufficient kernel resources are available. 130 131config HAVE_MEMBLOCK 132 bool 133 134config HAVE_MEMBLOCK_NODE_MAP 135 bool 136 137config HAVE_MEMBLOCK_PHYS_MAP 138 bool 139 140config HAVE_GENERIC_RCU_GUP 141 bool 142 143config ARCH_DISCARD_MEMBLOCK 144 bool 145 146config NO_BOOTMEM 147 bool 148 149config MEMORY_ISOLATION 150 bool 151 152config MOVABLE_NODE 153 bool "Enable to assign a node which has only movable memory" 154 depends on HAVE_MEMBLOCK 155 depends on NO_BOOTMEM 156 depends on X86_64 157 depends on NUMA 158 default n 159 help 160 Allow a node to have only movable memory. Pages used by the kernel, 161 such as direct mapping pages cannot be migrated. So the corresponding 162 memory device cannot be hotplugged. This option allows the following 163 two things: 164 - When the system is booting, node full of hotpluggable memory can 165 be arranged to have only movable memory so that the whole node can 166 be hot-removed. (need movable_node boot option specified). 167 - After the system is up, the option allows users to online all the 168 memory of a node as movable memory so that the whole node can be 169 hot-removed. 170 171 Users who don't use the memory hotplug feature are fine with this 172 option on since they don't specify movable_node boot option or they 173 don't online memory as movable. 174 175 Say Y here if you want to hotplug a whole node. 176 Say N here if you want kernel to use memory on all nodes evenly. 177 178# 179# Only be set on architectures that have completely implemented memory hotplug 180# feature. If you are not sure, don't touch it. 181# 182config HAVE_BOOTMEM_INFO_NODE 183 def_bool n 184 185# eventually, we can have this option just 'select SPARSEMEM' 186config MEMORY_HOTPLUG 187 bool "Allow for memory hot-add" 188 depends on SPARSEMEM || X86_64_ACPI_NUMA 189 depends on ARCH_ENABLE_MEMORY_HOTPLUG 190 depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390) 191 192config MEMORY_HOTPLUG_SPARSE 193 def_bool y 194 depends on SPARSEMEM && MEMORY_HOTPLUG 195 196config MEMORY_HOTREMOVE 197 bool "Allow for memory hot remove" 198 select MEMORY_ISOLATION 199 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 200 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 201 depends on MIGRATION 202 203# Heavily threaded applications may benefit from splitting the mm-wide 204# page_table_lock, so that faults on different parts of the user address 205# space can be handled with less contention: split it at this NR_CPUS. 206# Default to 4 for wider testing, though 8 might be more appropriate. 207# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 208# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 209# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 210# 211config SPLIT_PTLOCK_CPUS 212 int 213 default "999999" if !MMU 214 default "999999" if ARM && !CPU_CACHE_VIPT 215 default "999999" if PARISC && !PA20 216 default "4" 217 218config ARCH_ENABLE_SPLIT_PMD_PTLOCK 219 bool 220 221# 222# support for memory balloon 223config MEMORY_BALLOON 224 bool 225 226# 227# support for memory balloon compaction 228config BALLOON_COMPACTION 229 bool "Allow for balloon memory compaction/migration" 230 def_bool y 231 depends on COMPACTION && MEMORY_BALLOON 232 help 233 Memory fragmentation introduced by ballooning might reduce 234 significantly the number of 2MB contiguous memory blocks that can be 235 used within a guest, thus imposing performance penalties associated 236 with the reduced number of transparent huge pages that could be used 237 by the guest workload. Allowing the compaction & migration for memory 238 pages enlisted as being part of memory balloon devices avoids the 239 scenario aforementioned and helps improving memory defragmentation. 240 241# 242# support for memory compaction 243config COMPACTION 244 bool "Allow for memory compaction" 245 def_bool y 246 select MIGRATION 247 depends on MMU 248 help 249 Allows the compaction of memory for the allocation of huge pages. 250 251# 252# support for page migration 253# 254config MIGRATION 255 bool "Page migration" 256 def_bool y 257 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 258 help 259 Allows the migration of the physical location of pages of processes 260 while the virtual addresses are not changed. This is useful in 261 two situations. The first is on NUMA systems to put pages nearer 262 to the processors accessing. The second is when allocating huge 263 pages as migration can relocate pages to satisfy a huge page 264 allocation instead of reclaiming. 265 266config ARCH_ENABLE_HUGEPAGE_MIGRATION 267 bool 268 269config PHYS_ADDR_T_64BIT 270 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT 271 272config ZONE_DMA_FLAG 273 int 274 default "0" if !ZONE_DMA 275 default "1" 276 277config BOUNCE 278 bool "Enable bounce buffers" 279 default y 280 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) 281 help 282 Enable bounce buffers for devices that cannot access 283 the full range of memory available to the CPU. Enabled 284 by default when ZONE_DMA or HIGHMEM is selected, but you 285 may say n to override this. 286 287# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often 288# have more than 4GB of memory, but we don't currently use the IOTLB to present 289# a 32-bit address to OHCI. So we need to use a bounce pool instead. 290config NEED_BOUNCE_POOL 291 bool 292 default y if TILE && USB_OHCI_HCD 293 294config NR_QUICK 295 int 296 depends on QUICKLIST 297 default "2" if AVR32 298 default "1" 299 300config VIRT_TO_BUS 301 bool 302 help 303 An architecture should select this if it implements the 304 deprecated interface virt_to_bus(). All new architectures 305 should probably not select this. 306 307 308config MMU_NOTIFIER 309 bool 310 select SRCU 311 312config KSM 313 bool "Enable KSM for page merging" 314 depends on MMU 315 help 316 Enable Kernel Samepage Merging: KSM periodically scans those areas 317 of an application's address space that an app has advised may be 318 mergeable. When it finds pages of identical content, it replaces 319 the many instances by a single page with that content, so 320 saving memory until one or another app needs to modify the content. 321 Recommended for use with KVM, or with other duplicative applications. 322 See Documentation/vm/ksm.txt for more information: KSM is inactive 323 until a program has madvised that an area is MADV_MERGEABLE, and 324 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 325 326config DEFAULT_MMAP_MIN_ADDR 327 int "Low address space to protect from user allocation" 328 depends on MMU 329 default 4096 330 help 331 This is the portion of low virtual memory which should be protected 332 from userspace allocation. Keeping a user from writing to low pages 333 can help reduce the impact of kernel NULL pointer bugs. 334 335 For most ia64, ppc64 and x86 users with lots of address space 336 a value of 65536 is reasonable and should cause no problems. 337 On arm and other archs it should not be higher than 32768. 338 Programs which use vm86 functionality or have some need to map 339 this low address space will need CAP_SYS_RAWIO or disable this 340 protection by setting the value to 0. 341 342 This value can be changed after boot using the 343 /proc/sys/vm/mmap_min_addr tunable. 344 345config ARCH_SUPPORTS_MEMORY_FAILURE 346 bool 347 348config MEMORY_FAILURE 349 depends on MMU 350 depends on ARCH_SUPPORTS_MEMORY_FAILURE 351 bool "Enable recovery from hardware memory errors" 352 select MEMORY_ISOLATION 353 select RAS 354 help 355 Enables code to recover from some memory failures on systems 356 with MCA recovery. This allows a system to continue running 357 even when some of its memory has uncorrected errors. This requires 358 special hardware support and typically ECC memory. 359 360config HWPOISON_INJECT 361 tristate "HWPoison pages injector" 362 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 363 select PROC_PAGE_MONITOR 364 365config NOMMU_INITIAL_TRIM_EXCESS 366 int "Turn on mmap() excess space trimming before booting" 367 depends on !MMU 368 default 1 369 help 370 The NOMMU mmap() frequently needs to allocate large contiguous chunks 371 of memory on which to store mappings, but it can only ask the system 372 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 373 more than it requires. To deal with this, mmap() is able to trim off 374 the excess and return it to the allocator. 375 376 If trimming is enabled, the excess is trimmed off and returned to the 377 system allocator, which can cause extra fragmentation, particularly 378 if there are a lot of transient processes. 379 380 If trimming is disabled, the excess is kept, but not used, which for 381 long-term mappings means that the space is wasted. 382 383 Trimming can be dynamically controlled through a sysctl option 384 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 385 excess pages there must be before trimming should occur, or zero if 386 no trimming is to occur. 387 388 This option specifies the initial value of this option. The default 389 of 1 says that all excess pages should be trimmed. 390 391 See Documentation/nommu-mmap.txt for more information. 392 393config TRANSPARENT_HUGEPAGE 394 bool "Transparent Hugepage Support" 395 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE 396 select COMPACTION 397 help 398 Transparent Hugepages allows the kernel to use huge pages and 399 huge tlb transparently to the applications whenever possible. 400 This feature can improve computing performance to certain 401 applications by speeding up page faults during memory 402 allocation, by reducing the number of tlb misses and by speeding 403 up the pagetable walking. 404 405 If memory constrained on embedded, you may want to say N. 406 407choice 408 prompt "Transparent Hugepage Support sysfs defaults" 409 depends on TRANSPARENT_HUGEPAGE 410 default TRANSPARENT_HUGEPAGE_ALWAYS 411 help 412 Selects the sysfs defaults for Transparent Hugepage Support. 413 414 config TRANSPARENT_HUGEPAGE_ALWAYS 415 bool "always" 416 help 417 Enabling Transparent Hugepage always, can increase the 418 memory footprint of applications without a guaranteed 419 benefit but it will work automatically for all applications. 420 421 config TRANSPARENT_HUGEPAGE_MADVISE 422 bool "madvise" 423 help 424 Enabling Transparent Hugepage madvise, will only provide a 425 performance improvement benefit to the applications using 426 madvise(MADV_HUGEPAGE) but it won't risk to increase the 427 memory footprint of applications without a guaranteed 428 benefit. 429endchoice 430 431# 432# UP and nommu archs use km based percpu allocator 433# 434config NEED_PER_CPU_KM 435 depends on !SMP 436 bool 437 default y 438 439config CLEANCACHE 440 bool "Enable cleancache driver to cache clean pages if tmem is present" 441 default n 442 help 443 Cleancache can be thought of as a page-granularity victim cache 444 for clean pages that the kernel's pageframe replacement algorithm 445 (PFRA) would like to keep around, but can't since there isn't enough 446 memory. So when the PFRA "evicts" a page, it first attempts to use 447 cleancache code to put the data contained in that page into 448 "transcendent memory", memory that is not directly accessible or 449 addressable by the kernel and is of unknown and possibly 450 time-varying size. And when a cleancache-enabled 451 filesystem wishes to access a page in a file on disk, it first 452 checks cleancache to see if it already contains it; if it does, 453 the page is copied into the kernel and a disk access is avoided. 454 When a transcendent memory driver is available (such as zcache or 455 Xen transcendent memory), a significant I/O reduction 456 may be achieved. When none is available, all cleancache calls 457 are reduced to a single pointer-compare-against-NULL resulting 458 in a negligible performance hit. 459 460 If unsure, say Y to enable cleancache 461 462config FRONTSWAP 463 bool "Enable frontswap to cache swap pages if tmem is present" 464 depends on SWAP 465 default n 466 help 467 Frontswap is so named because it can be thought of as the opposite 468 of a "backing" store for a swap device. The data is stored into 469 "transcendent memory", memory that is not directly accessible or 470 addressable by the kernel and is of unknown and possibly 471 time-varying size. When space in transcendent memory is available, 472 a significant swap I/O reduction may be achieved. When none is 473 available, all frontswap calls are reduced to a single pointer- 474 compare-against-NULL resulting in a negligible performance hit 475 and swap data is stored as normal on the matching swap device. 476 477 If unsure, say Y to enable frontswap. 478 479config CMA 480 bool "Contiguous Memory Allocator" 481 depends on HAVE_MEMBLOCK && MMU 482 select MIGRATION 483 select MEMORY_ISOLATION 484 help 485 This enables the Contiguous Memory Allocator which allows other 486 subsystems to allocate big physically-contiguous blocks of memory. 487 CMA reserves a region of memory and allows only movable pages to 488 be allocated from it. This way, the kernel can use the memory for 489 pagecache and when a subsystem requests for contiguous area, the 490 allocated pages are migrated away to serve the contiguous request. 491 492 If unsure, say "n". 493 494config CMA_DEBUG 495 bool "CMA debug messages (DEVELOPMENT)" 496 depends on DEBUG_KERNEL && CMA 497 help 498 Turns on debug messages in CMA. This produces KERN_DEBUG 499 messages for every CMA call as well as various messages while 500 processing calls such as dma_alloc_from_contiguous(). 501 This option does not affect warning and error messages. 502 503config CMA_DEBUGFS 504 bool "CMA debugfs interface" 505 depends on CMA && DEBUG_FS 506 help 507 Turns on the DebugFS interface for CMA. 508 509config CMA_AREAS 510 int "Maximum count of the CMA areas" 511 depends on CMA 512 default 7 513 help 514 CMA allows to create CMA areas for particular purpose, mainly, 515 used as device private area. This parameter sets the maximum 516 number of CMA area in the system. 517 518 If unsure, leave the default value "7". 519 520config MEM_SOFT_DIRTY 521 bool "Track memory changes" 522 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 523 select PROC_PAGE_MONITOR 524 help 525 This option enables memory changes tracking by introducing a 526 soft-dirty bit on pte-s. This bit it set when someone writes 527 into a page just as regular dirty bit, but unlike the latter 528 it can be cleared by hands. 529 530 See Documentation/vm/soft-dirty.txt for more details. 531 532config ZSWAP 533 bool "Compressed cache for swap pages (EXPERIMENTAL)" 534 depends on FRONTSWAP && CRYPTO=y 535 select CRYPTO_LZO 536 select ZPOOL 537 default n 538 help 539 A lightweight compressed cache for swap pages. It takes 540 pages that are in the process of being swapped out and attempts to 541 compress them into a dynamically allocated RAM-based memory pool. 542 This can result in a significant I/O reduction on swap device and, 543 in the case where decompressing from RAM is faster that swap device 544 reads, can also improve workload performance. 545 546 This is marked experimental because it is a new feature (as of 547 v3.11) that interacts heavily with memory reclaim. While these 548 interactions don't cause any known issues on simple memory setups, 549 they have not be fully explored on the large set of potential 550 configurations and workloads that exist. 551 552config ZPOOL 553 tristate "Common API for compressed memory storage" 554 default n 555 help 556 Compressed memory storage API. This allows using either zbud or 557 zsmalloc. 558 559config ZBUD 560 tristate "Low density storage for compressed pages" 561 default n 562 help 563 A special purpose allocator for storing compressed pages. 564 It is designed to store up to two compressed pages per physical 565 page. While this design limits storage density, it has simple and 566 deterministic reclaim properties that make it preferable to a higher 567 density approach when reclaim will be used. 568 569config ZSMALLOC 570 tristate "Memory allocator for compressed pages" 571 depends on MMU 572 default n 573 help 574 zsmalloc is a slab-based memory allocator designed to store 575 compressed RAM pages. zsmalloc uses virtual memory mapping 576 in order to reduce fragmentation. However, this results in a 577 non-standard allocator interface where a handle, not a pointer, is 578 returned by an alloc(). This handle must be mapped in order to 579 access the allocated space. 580 581config PGTABLE_MAPPING 582 bool "Use page table mapping to access object in zsmalloc" 583 depends on ZSMALLOC 584 help 585 By default, zsmalloc uses a copy-based object mapping method to 586 access allocations that span two pages. However, if a particular 587 architecture (ex, ARM) performs VM mapping faster than copying, 588 then you should select this. This causes zsmalloc to use page table 589 mapping rather than copying for object mapping. 590 591 You can check speed with zsmalloc benchmark: 592 https://github.com/spartacus06/zsmapbench 593 594config ZSMALLOC_STAT 595 bool "Export zsmalloc statistics" 596 depends on ZSMALLOC 597 select DEBUG_FS 598 help 599 This option enables code in the zsmalloc to collect various 600 statistics about whats happening in zsmalloc and exports that 601 information to userspace via debugfs. 602 If unsure, say N. 603 604config GENERIC_EARLY_IOREMAP 605 bool 606 607config MAX_STACK_SIZE_MB 608 int "Maximum user stack size for 32-bit processes (MB)" 609 default 80 610 range 8 256 if METAG 611 range 8 2048 612 depends on STACK_GROWSUP && (!64BIT || COMPAT) 613 help 614 This is the maximum stack size in Megabytes in the VM layout of 32-bit 615 user processes when the stack grows upwards (currently only on parisc 616 and metag arch). The stack will be located at the highest memory 617 address minus the given value, unless the RLIMIT_STACK hard limit is 618 changed to a smaller value in which case that is used. 619 620 A sane initial value is 80 MB. 621 622# For architectures that support deferred memory initialisation 623config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 624 bool 625 626config DEFERRED_STRUCT_PAGE_INIT 627 bool "Defer initialisation of struct pages to kswapd" 628 default n 629 depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 630 depends on MEMORY_HOTPLUG 631 help 632 Ordinarily all struct pages are initialised during early boot in a 633 single thread. On very large machines this can take a considerable 634 amount of time. If this option is set, large machines will bring up 635 a subset of memmap at boot and then initialise the rest in parallel 636 when kswapd starts. This has a potential performance impact on 637 processes running early in the lifetime of the systemm until kswapd 638 finishes the initialisation. 639 640config IDLE_PAGE_TRACKING 641 bool "Enable idle page tracking" 642 depends on SYSFS && MMU 643 select PAGE_EXTENSION if !64BIT 644 help 645 This feature allows to estimate the amount of user pages that have 646 not been touched during a given period of time. This information can 647 be useful to tune memory cgroup limits and/or for job placement 648 within a compute cluster. 649 650 See Documentation/vm/idle_page_tracking.txt for more details. 651 652config ZONE_DEVICE 653 bool "Device memory (pmem, etc...) hotplug support" if EXPERT 654 default !ZONE_DMA 655 depends on !ZONE_DMA 656 depends on MEMORY_HOTPLUG 657 depends on MEMORY_HOTREMOVE 658 depends on X86_64 #arch_add_memory() comprehends device memory 659 660 help 661 Device memory hotplug support allows for establishing pmem, 662 or other device driver discovered memory regions, in the 663 memmap. This allows pfn_to_page() lookups of otherwise 664 "device-physical" addresses which is needed for using a DAX 665 mapping in an O_DIRECT operation, among other things. 666 667 If FS_DAX is enabled, then say Y. 668 669config FRAME_VECTOR 670 bool 671