Kconfig 25 KB

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  1. config SELECT_MEMORY_MODEL
  2. def_bool y
  3. depends on ARCH_SELECT_MEMORY_MODEL
  4. choice
  5. prompt "Memory model"
  6. depends on SELECT_MEMORY_MODEL
  7. default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
  8. default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
  9. default FLATMEM_MANUAL
  10. config FLATMEM_MANUAL
  11. bool "Flat Memory"
  12. depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
  13. help
  14. This option allows you to change some of the ways that
  15. Linux manages its memory internally. Most users will
  16. only have one option here: FLATMEM. This is normal
  17. and a correct option.
  18. Some users of more advanced features like NUMA and
  19. memory hotplug may have different options here.
  20. DISCONTIGMEM is a more mature, better tested system,
  21. but is incompatible with memory hotplug and may suffer
  22. decreased performance over SPARSEMEM. If unsure between
  23. "Sparse Memory" and "Discontiguous Memory", choose
  24. "Discontiguous Memory".
  25. If unsure, choose this option (Flat Memory) over any other.
  26. config DISCONTIGMEM_MANUAL
  27. bool "Discontiguous Memory"
  28. depends on ARCH_DISCONTIGMEM_ENABLE
  29. help
  30. This option provides enhanced support for discontiguous
  31. memory systems, over FLATMEM. These systems have holes
  32. in their physical address spaces, and this option provides
  33. more efficient handling of these holes. However, the vast
  34. majority of hardware has quite flat address spaces, and
  35. can have degraded performance from the extra overhead that
  36. this option imposes.
  37. Many NUMA configurations will have this as the only option.
  38. If unsure, choose "Flat Memory" over this option.
  39. config SPARSEMEM_MANUAL
  40. bool "Sparse Memory"
  41. depends on ARCH_SPARSEMEM_ENABLE
  42. help
  43. This will be the only option for some systems, including
  44. memory hotplug systems. This is normal.
  45. For many other systems, this will be an alternative to
  46. "Discontiguous Memory". This option provides some potential
  47. performance benefits, along with decreased code complexity,
  48. but it is newer, and more experimental.
  49. If unsure, choose "Discontiguous Memory" or "Flat Memory"
  50. over this option.
  51. endchoice
  52. config DISCONTIGMEM
  53. def_bool y
  54. depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
  55. config SPARSEMEM
  56. def_bool y
  57. depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
  58. config FLATMEM
  59. def_bool y
  60. depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
  61. config FLAT_NODE_MEM_MAP
  62. def_bool y
  63. depends on !SPARSEMEM
  64. #
  65. # Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
  66. # to represent different areas of memory. This variable allows
  67. # those dependencies to exist individually.
  68. #
  69. config NEED_MULTIPLE_NODES
  70. def_bool y
  71. depends on DISCONTIGMEM || NUMA
  72. config HAVE_MEMORY_PRESENT
  73. def_bool y
  74. depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
  75. #
  76. # SPARSEMEM_EXTREME (which is the default) does some bootmem
  77. # allocations when memory_present() is called. If this cannot
  78. # be done on your architecture, select this option. However,
  79. # statically allocating the mem_section[] array can potentially
  80. # consume vast quantities of .bss, so be careful.
  81. #
  82. # This option will also potentially produce smaller runtime code
  83. # with gcc 3.4 and later.
  84. #
  85. config SPARSEMEM_STATIC
  86. bool
  87. #
  88. # Architecture platforms which require a two level mem_section in SPARSEMEM
  89. # must select this option. This is usually for architecture platforms with
  90. # an extremely sparse physical address space.
  91. #
  92. config SPARSEMEM_EXTREME
  93. def_bool y
  94. depends on SPARSEMEM && !SPARSEMEM_STATIC
  95. config SPARSEMEM_VMEMMAP_ENABLE
  96. bool
  97. config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
  98. def_bool y
  99. depends on SPARSEMEM && X86_64
  100. config SPARSEMEM_VMEMMAP
  101. bool "Sparse Memory virtual memmap"
  102. depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
  103. default y
  104. help
  105. SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
  106. pfn_to_page and page_to_pfn operations. This is the most
  107. efficient option when sufficient kernel resources are available.
  108. config HAVE_MEMBLOCK
  109. bool
  110. config HAVE_MEMBLOCK_NODE_MAP
  111. bool
  112. config HAVE_MEMBLOCK_PHYS_MAP
  113. bool
  114. config HAVE_GENERIC_GUP
  115. bool
  116. config ARCH_DISCARD_MEMBLOCK
  117. bool
  118. config NO_BOOTMEM
  119. bool
  120. config MEMORY_ISOLATION
  121. bool
  122. #
  123. # Only be set on architectures that have completely implemented memory hotplug
  124. # feature. If you are not sure, don't touch it.
  125. #
  126. config HAVE_BOOTMEM_INFO_NODE
  127. def_bool n
  128. # eventually, we can have this option just 'select SPARSEMEM'
  129. config MEMORY_HOTPLUG
  130. bool "Allow for memory hot-add"
  131. depends on SPARSEMEM || X86_64_ACPI_NUMA
  132. depends on ARCH_ENABLE_MEMORY_HOTPLUG
  133. config MEMORY_HOTPLUG_SPARSE
  134. def_bool y
  135. depends on SPARSEMEM && MEMORY_HOTPLUG
  136. config MEMORY_HOTPLUG_DEFAULT_ONLINE
  137. bool "Online the newly added memory blocks by default"
  138. default n
  139. depends on MEMORY_HOTPLUG
  140. help
  141. This option sets the default policy setting for memory hotplug
  142. onlining policy (/sys/devices/system/memory/auto_online_blocks) which
  143. determines what happens to newly added memory regions. Policy setting
  144. can always be changed at runtime.
  145. See Documentation/memory-hotplug.txt for more information.
  146. Say Y here if you want all hot-plugged memory blocks to appear in
  147. 'online' state by default.
  148. Say N here if you want the default policy to keep all hot-plugged
  149. memory blocks in 'offline' state.
  150. config MEMORY_HOTREMOVE
  151. bool "Allow for memory hot remove"
  152. select MEMORY_ISOLATION
  153. select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
  154. depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
  155. depends on MIGRATION
  156. # Heavily threaded applications may benefit from splitting the mm-wide
  157. # page_table_lock, so that faults on different parts of the user address
  158. # space can be handled with less contention: split it at this NR_CPUS.
  159. # Default to 4 for wider testing, though 8 might be more appropriate.
  160. # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
  161. # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
  162. # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
  163. #
  164. config SPLIT_PTLOCK_CPUS
  165. int
  166. default "999999" if !MMU
  167. default "999999" if ARM && !CPU_CACHE_VIPT
  168. default "999999" if PARISC && !PA20
  169. default "4"
  170. config ARCH_ENABLE_SPLIT_PMD_PTLOCK
  171. bool
  172. #
  173. # support for memory balloon
  174. config MEMORY_BALLOON
  175. bool
  176. #
  177. # support for memory balloon compaction
  178. config BALLOON_COMPACTION
  179. bool "Allow for balloon memory compaction/migration"
  180. def_bool y
  181. depends on COMPACTION && MEMORY_BALLOON
  182. help
  183. Memory fragmentation introduced by ballooning might reduce
  184. significantly the number of 2MB contiguous memory blocks that can be
  185. used within a guest, thus imposing performance penalties associated
  186. with the reduced number of transparent huge pages that could be used
  187. by the guest workload. Allowing the compaction & migration for memory
  188. pages enlisted as being part of memory balloon devices avoids the
  189. scenario aforementioned and helps improving memory defragmentation.
  190. #
  191. # support for memory compaction
  192. config COMPACTION
  193. bool "Allow for memory compaction"
  194. def_bool y
  195. select MIGRATION
  196. depends on MMU
  197. help
  198. Compaction is the only memory management component to form
  199. high order (larger physically contiguous) memory blocks
  200. reliably. The page allocator relies on compaction heavily and
  201. the lack of the feature can lead to unexpected OOM killer
  202. invocations for high order memory requests. You shouldn't
  203. disable this option unless there really is a strong reason for
  204. it and then we would be really interested to hear about that at
  205. linux-mm@kvack.org.
  206. #
  207. # support for page migration
  208. #
  209. config MIGRATION
  210. bool "Page migration"
  211. def_bool y
  212. depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
  213. help
  214. Allows the migration of the physical location of pages of processes
  215. while the virtual addresses are not changed. This is useful in
  216. two situations. The first is on NUMA systems to put pages nearer
  217. to the processors accessing. The second is when allocating huge
  218. pages as migration can relocate pages to satisfy a huge page
  219. allocation instead of reclaiming.
  220. config ARCH_ENABLE_HUGEPAGE_MIGRATION
  221. bool
  222. config ARCH_ENABLE_THP_MIGRATION
  223. bool
  224. config PHYS_ADDR_T_64BIT
  225. def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
  226. config BOUNCE
  227. bool "Enable bounce buffers"
  228. default y
  229. depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
  230. help
  231. Enable bounce buffers for devices that cannot access
  232. the full range of memory available to the CPU. Enabled
  233. by default when ZONE_DMA or HIGHMEM is selected, but you
  234. may say n to override this.
  235. config NR_QUICK
  236. int
  237. depends on QUICKLIST
  238. default "1"
  239. config VIRT_TO_BUS
  240. bool
  241. help
  242. An architecture should select this if it implements the
  243. deprecated interface virt_to_bus(). All new architectures
  244. should probably not select this.
  245. config MMU_NOTIFIER
  246. bool
  247. select SRCU
  248. config KSM
  249. bool "Enable KSM for page merging"
  250. depends on MMU
  251. help
  252. Enable Kernel Samepage Merging: KSM periodically scans those areas
  253. of an application's address space that an app has advised may be
  254. mergeable. When it finds pages of identical content, it replaces
  255. the many instances by a single page with that content, so
  256. saving memory until one or another app needs to modify the content.
  257. Recommended for use with KVM, or with other duplicative applications.
  258. See Documentation/vm/ksm.txt for more information: KSM is inactive
  259. until a program has madvised that an area is MADV_MERGEABLE, and
  260. root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
  261. config DEFAULT_MMAP_MIN_ADDR
  262. int "Low address space to protect from user allocation"
  263. depends on MMU
  264. default 4096
  265. help
  266. This is the portion of low virtual memory which should be protected
  267. from userspace allocation. Keeping a user from writing to low pages
  268. can help reduce the impact of kernel NULL pointer bugs.
  269. For most ia64, ppc64 and x86 users with lots of address space
  270. a value of 65536 is reasonable and should cause no problems.
  271. On arm and other archs it should not be higher than 32768.
  272. Programs which use vm86 functionality or have some need to map
  273. this low address space will need CAP_SYS_RAWIO or disable this
  274. protection by setting the value to 0.
  275. This value can be changed after boot using the
  276. /proc/sys/vm/mmap_min_addr tunable.
  277. config ARCH_SUPPORTS_MEMORY_FAILURE
  278. bool
  279. config MEMORY_FAILURE
  280. depends on MMU
  281. depends on ARCH_SUPPORTS_MEMORY_FAILURE
  282. bool "Enable recovery from hardware memory errors"
  283. select MEMORY_ISOLATION
  284. select RAS
  285. help
  286. Enables code to recover from some memory failures on systems
  287. with MCA recovery. This allows a system to continue running
  288. even when some of its memory has uncorrected errors. This requires
  289. special hardware support and typically ECC memory.
  290. config HWPOISON_INJECT
  291. tristate "HWPoison pages injector"
  292. depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
  293. select PROC_PAGE_MONITOR
  294. config NOMMU_INITIAL_TRIM_EXCESS
  295. int "Turn on mmap() excess space trimming before booting"
  296. depends on !MMU
  297. default 1
  298. help
  299. The NOMMU mmap() frequently needs to allocate large contiguous chunks
  300. of memory on which to store mappings, but it can only ask the system
  301. allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
  302. more than it requires. To deal with this, mmap() is able to trim off
  303. the excess and return it to the allocator.
  304. If trimming is enabled, the excess is trimmed off and returned to the
  305. system allocator, which can cause extra fragmentation, particularly
  306. if there are a lot of transient processes.
  307. If trimming is disabled, the excess is kept, but not used, which for
  308. long-term mappings means that the space is wasted.
  309. Trimming can be dynamically controlled through a sysctl option
  310. (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
  311. excess pages there must be before trimming should occur, or zero if
  312. no trimming is to occur.
  313. This option specifies the initial value of this option. The default
  314. of 1 says that all excess pages should be trimmed.
  315. See Documentation/nommu-mmap.txt for more information.
  316. config TRANSPARENT_HUGEPAGE
  317. bool "Transparent Hugepage Support"
  318. depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
  319. select COMPACTION
  320. select RADIX_TREE_MULTIORDER
  321. help
  322. Transparent Hugepages allows the kernel to use huge pages and
  323. huge tlb transparently to the applications whenever possible.
  324. This feature can improve computing performance to certain
  325. applications by speeding up page faults during memory
  326. allocation, by reducing the number of tlb misses and by speeding
  327. up the pagetable walking.
  328. If memory constrained on embedded, you may want to say N.
  329. choice
  330. prompt "Transparent Hugepage Support sysfs defaults"
  331. depends on TRANSPARENT_HUGEPAGE
  332. default TRANSPARENT_HUGEPAGE_ALWAYS
  333. help
  334. Selects the sysfs defaults for Transparent Hugepage Support.
  335. config TRANSPARENT_HUGEPAGE_ALWAYS
  336. bool "always"
  337. help
  338. Enabling Transparent Hugepage always, can increase the
  339. memory footprint of applications without a guaranteed
  340. benefit but it will work automatically for all applications.
  341. config TRANSPARENT_HUGEPAGE_MADVISE
  342. bool "madvise"
  343. help
  344. Enabling Transparent Hugepage madvise, will only provide a
  345. performance improvement benefit to the applications using
  346. madvise(MADV_HUGEPAGE) but it won't risk to increase the
  347. memory footprint of applications without a guaranteed
  348. benefit.
  349. endchoice
  350. config ARCH_WANTS_THP_SWAP
  351. def_bool n
  352. config THP_SWAP
  353. def_bool y
  354. depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP
  355. help
  356. Swap transparent huge pages in one piece, without splitting.
  357. XXX: For now this only does clustered swap space allocation.
  358. For selection by architectures with reasonable THP sizes.
  359. config TRANSPARENT_HUGE_PAGECACHE
  360. def_bool y
  361. depends on TRANSPARENT_HUGEPAGE
  362. #
  363. # UP and nommu archs use km based percpu allocator
  364. #
  365. config NEED_PER_CPU_KM
  366. depends on !SMP
  367. bool
  368. default y
  369. config CLEANCACHE
  370. bool "Enable cleancache driver to cache clean pages if tmem is present"
  371. default n
  372. help
  373. Cleancache can be thought of as a page-granularity victim cache
  374. for clean pages that the kernel's pageframe replacement algorithm
  375. (PFRA) would like to keep around, but can't since there isn't enough
  376. memory. So when the PFRA "evicts" a page, it first attempts to use
  377. cleancache code to put the data contained in that page into
  378. "transcendent memory", memory that is not directly accessible or
  379. addressable by the kernel and is of unknown and possibly
  380. time-varying size. And when a cleancache-enabled
  381. filesystem wishes to access a page in a file on disk, it first
  382. checks cleancache to see if it already contains it; if it does,
  383. the page is copied into the kernel and a disk access is avoided.
  384. When a transcendent memory driver is available (such as zcache or
  385. Xen transcendent memory), a significant I/O reduction
  386. may be achieved. When none is available, all cleancache calls
  387. are reduced to a single pointer-compare-against-NULL resulting
  388. in a negligible performance hit.
  389. If unsure, say Y to enable cleancache
  390. config FRONTSWAP
  391. bool "Enable frontswap to cache swap pages if tmem is present"
  392. depends on SWAP
  393. default n
  394. help
  395. Frontswap is so named because it can be thought of as the opposite
  396. of a "backing" store for a swap device. The data is stored into
  397. "transcendent memory", memory that is not directly accessible or
  398. addressable by the kernel and is of unknown and possibly
  399. time-varying size. When space in transcendent memory is available,
  400. a significant swap I/O reduction may be achieved. When none is
  401. available, all frontswap calls are reduced to a single pointer-
  402. compare-against-NULL resulting in a negligible performance hit
  403. and swap data is stored as normal on the matching swap device.
  404. If unsure, say Y to enable frontswap.
  405. config CMA
  406. bool "Contiguous Memory Allocator"
  407. depends on HAVE_MEMBLOCK && MMU
  408. select MIGRATION
  409. select MEMORY_ISOLATION
  410. help
  411. This enables the Contiguous Memory Allocator which allows other
  412. subsystems to allocate big physically-contiguous blocks of memory.
  413. CMA reserves a region of memory and allows only movable pages to
  414. be allocated from it. This way, the kernel can use the memory for
  415. pagecache and when a subsystem requests for contiguous area, the
  416. allocated pages are migrated away to serve the contiguous request.
  417. If unsure, say "n".
  418. config CMA_DEBUG
  419. bool "CMA debug messages (DEVELOPMENT)"
  420. depends on DEBUG_KERNEL && CMA
  421. help
  422. Turns on debug messages in CMA. This produces KERN_DEBUG
  423. messages for every CMA call as well as various messages while
  424. processing calls such as dma_alloc_from_contiguous().
  425. This option does not affect warning and error messages.
  426. config CMA_DEBUGFS
  427. bool "CMA debugfs interface"
  428. depends on CMA && DEBUG_FS
  429. help
  430. Turns on the DebugFS interface for CMA.
  431. config CMA_AREAS
  432. int "Maximum count of the CMA areas"
  433. depends on CMA
  434. default 7
  435. help
  436. CMA allows to create CMA areas for particular purpose, mainly,
  437. used as device private area. This parameter sets the maximum
  438. number of CMA area in the system.
  439. If unsure, leave the default value "7".
  440. config MEM_SOFT_DIRTY
  441. bool "Track memory changes"
  442. depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
  443. select PROC_PAGE_MONITOR
  444. help
  445. This option enables memory changes tracking by introducing a
  446. soft-dirty bit on pte-s. This bit it set when someone writes
  447. into a page just as regular dirty bit, but unlike the latter
  448. it can be cleared by hands.
  449. See Documentation/vm/soft-dirty.txt for more details.
  450. config ZSWAP
  451. bool "Compressed cache for swap pages (EXPERIMENTAL)"
  452. depends on FRONTSWAP && CRYPTO=y
  453. select CRYPTO_LZO
  454. select ZPOOL
  455. default n
  456. help
  457. A lightweight compressed cache for swap pages. It takes
  458. pages that are in the process of being swapped out and attempts to
  459. compress them into a dynamically allocated RAM-based memory pool.
  460. This can result in a significant I/O reduction on swap device and,
  461. in the case where decompressing from RAM is faster that swap device
  462. reads, can also improve workload performance.
  463. This is marked experimental because it is a new feature (as of
  464. v3.11) that interacts heavily with memory reclaim. While these
  465. interactions don't cause any known issues on simple memory setups,
  466. they have not be fully explored on the large set of potential
  467. configurations and workloads that exist.
  468. config ZPOOL
  469. tristate "Common API for compressed memory storage"
  470. default n
  471. help
  472. Compressed memory storage API. This allows using either zbud or
  473. zsmalloc.
  474. config ZBUD
  475. tristate "Low (Up to 2x) density storage for compressed pages"
  476. default n
  477. help
  478. A special purpose allocator for storing compressed pages.
  479. It is designed to store up to two compressed pages per physical
  480. page. While this design limits storage density, it has simple and
  481. deterministic reclaim properties that make it preferable to a higher
  482. density approach when reclaim will be used.
  483. config Z3FOLD
  484. tristate "Up to 3x density storage for compressed pages"
  485. depends on ZPOOL
  486. default n
  487. help
  488. A special purpose allocator for storing compressed pages.
  489. It is designed to store up to three compressed pages per physical
  490. page. It is a ZBUD derivative so the simplicity and determinism are
  491. still there.
  492. config ZSMALLOC
  493. tristate "Memory allocator for compressed pages"
  494. depends on MMU
  495. default n
  496. help
  497. zsmalloc is a slab-based memory allocator designed to store
  498. compressed RAM pages. zsmalloc uses virtual memory mapping
  499. in order to reduce fragmentation. However, this results in a
  500. non-standard allocator interface where a handle, not a pointer, is
  501. returned by an alloc(). This handle must be mapped in order to
  502. access the allocated space.
  503. config PGTABLE_MAPPING
  504. bool "Use page table mapping to access object in zsmalloc"
  505. depends on ZSMALLOC
  506. help
  507. By default, zsmalloc uses a copy-based object mapping method to
  508. access allocations that span two pages. However, if a particular
  509. architecture (ex, ARM) performs VM mapping faster than copying,
  510. then you should select this. This causes zsmalloc to use page table
  511. mapping rather than copying for object mapping.
  512. You can check speed with zsmalloc benchmark:
  513. https://github.com/spartacus06/zsmapbench
  514. config ZSMALLOC_STAT
  515. bool "Export zsmalloc statistics"
  516. depends on ZSMALLOC
  517. select DEBUG_FS
  518. help
  519. This option enables code in the zsmalloc to collect various
  520. statistics about whats happening in zsmalloc and exports that
  521. information to userspace via debugfs.
  522. If unsure, say N.
  523. config GENERIC_EARLY_IOREMAP
  524. bool
  525. config MAX_STACK_SIZE_MB
  526. int "Maximum user stack size for 32-bit processes (MB)"
  527. default 80
  528. range 8 2048
  529. depends on STACK_GROWSUP && (!64BIT || COMPAT)
  530. help
  531. This is the maximum stack size in Megabytes in the VM layout of 32-bit
  532. user processes when the stack grows upwards (currently only on parisc
  533. arch). The stack will be located at the highest memory address minus
  534. the given value, unless the RLIMIT_STACK hard limit is changed to a
  535. smaller value in which case that is used.
  536. A sane initial value is 80 MB.
  537. config DEFERRED_STRUCT_PAGE_INIT
  538. bool "Defer initialisation of struct pages to kthreads"
  539. default n
  540. depends on NO_BOOTMEM
  541. depends on !FLATMEM
  542. depends on !NEED_PER_CPU_KM
  543. help
  544. Ordinarily all struct pages are initialised during early boot in a
  545. single thread. On very large machines this can take a considerable
  546. amount of time. If this option is set, large machines will bring up
  547. a subset of memmap at boot and then initialise the rest in parallel
  548. by starting one-off "pgdatinitX" kernel thread for each node X. This
  549. has a potential performance impact on processes running early in the
  550. lifetime of the system until these kthreads finish the
  551. initialisation.
  552. config IDLE_PAGE_TRACKING
  553. bool "Enable idle page tracking"
  554. depends on SYSFS && MMU
  555. select PAGE_EXTENSION if !64BIT
  556. help
  557. This feature allows to estimate the amount of user pages that have
  558. not been touched during a given period of time. This information can
  559. be useful to tune memory cgroup limits and/or for job placement
  560. within a compute cluster.
  561. See Documentation/vm/idle_page_tracking.txt for more details.
  562. # arch_add_memory() comprehends device memory
  563. config ARCH_HAS_ZONE_DEVICE
  564. bool
  565. config ZONE_DEVICE
  566. bool "Device memory (pmem, HMM, etc...) hotplug support"
  567. depends on MEMORY_HOTPLUG
  568. depends on MEMORY_HOTREMOVE
  569. depends on SPARSEMEM_VMEMMAP
  570. depends on ARCH_HAS_ZONE_DEVICE
  571. select RADIX_TREE_MULTIORDER
  572. help
  573. Device memory hotplug support allows for establishing pmem,
  574. or other device driver discovered memory regions, in the
  575. memmap. This allows pfn_to_page() lookups of otherwise
  576. "device-physical" addresses which is needed for using a DAX
  577. mapping in an O_DIRECT operation, among other things.
  578. If FS_DAX is enabled, then say Y.
  579. config ARCH_HAS_HMM
  580. bool
  581. default y
  582. depends on (X86_64 || PPC64)
  583. depends on ZONE_DEVICE
  584. depends on MMU && 64BIT
  585. depends on MEMORY_HOTPLUG
  586. depends on MEMORY_HOTREMOVE
  587. depends on SPARSEMEM_VMEMMAP
  588. config MIGRATE_VMA_HELPER
  589. bool
  590. config DEV_PAGEMAP_OPS
  591. bool
  592. config HMM
  593. bool
  594. select MIGRATE_VMA_HELPER
  595. config HMM_MIRROR
  596. bool "HMM mirror CPU page table into a device page table"
  597. depends on ARCH_HAS_HMM
  598. select MMU_NOTIFIER
  599. select HMM
  600. help
  601. Select HMM_MIRROR if you want to mirror range of the CPU page table of a
  602. process into a device page table. Here, mirror means "keep synchronized".
  603. Prerequisites: the device must provide the ability to write-protect its
  604. page tables (at PAGE_SIZE granularity), and must be able to recover from
  605. the resulting potential page faults.
  606. config DEVICE_PRIVATE
  607. bool "Unaddressable device memory (GPU memory, ...)"
  608. depends on ARCH_HAS_HMM
  609. select HMM
  610. select DEV_PAGEMAP_OPS
  611. help
  612. Allows creation of struct pages to represent unaddressable device
  613. memory; i.e., memory that is only accessible from the device (or
  614. group of devices). You likely also want to select HMM_MIRROR.
  615. config DEVICE_PUBLIC
  616. bool "Addressable device memory (like GPU memory)"
  617. depends on ARCH_HAS_HMM
  618. select HMM
  619. select DEV_PAGEMAP_OPS
  620. help
  621. Allows creation of struct pages to represent addressable device
  622. memory; i.e., memory that is accessible from both the device and
  623. the CPU
  624. config FRAME_VECTOR
  625. bool
  626. config ARCH_USES_HIGH_VMA_FLAGS
  627. bool
  628. config ARCH_HAS_PKEYS
  629. bool
  630. config PERCPU_STATS
  631. bool "Collect percpu memory statistics"
  632. default n
  633. help
  634. This feature collects and exposes statistics via debugfs. The
  635. information includes global and per chunk statistics, which can
  636. be used to help understand percpu memory usage.
  637. config GUP_BENCHMARK
  638. bool "Enable infrastructure for get_user_pages_fast() benchmarking"
  639. default n
  640. help
  641. Provides /sys/kernel/debug/gup_benchmark that helps with testing
  642. performance of get_user_pages_fast().
  643. See tools/testing/selftests/vm/gup_benchmark.c