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Dave Hansene1785e82005-06-23 00:07:49 -07001config SELECT_MEMORY_MODEL
2 def_bool y
Kees Cooka8826ee2013-01-16 18:54:17 -08003 depends on ARCH_SELECT_MEMORY_MODEL
Dave Hansene1785e82005-06-23 00:07:49 -07004
Dave Hansen3a9da762005-06-23 00:07:42 -07005choice
6 prompt "Memory model"
Dave Hansene1785e82005-06-23 00:07:49 -07007 depends on SELECT_MEMORY_MODEL
8 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
Andy Whitcroftd41dee32005-06-23 00:07:54 -07009 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
Dave Hansene1785e82005-06-23 00:07:49 -070010 default FLATMEM_MANUAL
Dave Hansen3a9da762005-06-23 00:07:42 -070011
Dave Hansene1785e82005-06-23 00:07:49 -070012config FLATMEM_MANUAL
Dave Hansen3a9da762005-06-23 00:07:42 -070013 bool "Flat Memory"
Anton Blanchardc898ec12006-01-06 00:12:07 -080014 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
Dave Hansen3a9da762005-06-23 00:07:42 -070015 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
Andy Whitcroftd41dee32005-06-23 00:07:54 -070021 Some users of more advanced features like NUMA and
22 memory hotplug may have different options here.
Geert Uytterhoeven18f65332013-09-15 12:01:33 +020023 DISCONTIGMEM is a more mature, better tested system,
Andy Whitcroftd41dee32005-06-23 00:07:54 -070024 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.
Dave Hansen3a9da762005-06-23 00:07:42 -070030
Dave Hansene1785e82005-06-23 00:07:49 -070031config DISCONTIGMEM_MANUAL
Dave Hansenf3519f92005-09-16 19:27:54 -070032 bool "Discontiguous Memory"
Dave Hansen3a9da762005-06-23 00:07:42 -070033 depends on ARCH_DISCONTIGMEM_ENABLE
34 help
Dave Hansen785dcd42005-06-23 00:07:50 -070035 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
Philipp Marekad3d0a32007-10-20 02:46:58 +020040 can have degraded performance from the extra overhead that
Dave Hansen785dcd42005-06-23 00:07:50 -070041 this option imposes.
42
43 Many NUMA configurations will have this as the only option.
44
Dave Hansen3a9da762005-06-23 00:07:42 -070045 If unsure, choose "Flat Memory" over this option.
46
Andy Whitcroftd41dee32005-06-23 00:07:54 -070047config 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
Dave Hansenf3519f92005-09-16 19:27:54 -070055 "Discontiguous Memory". This option provides some potential
Andy Whitcroftd41dee32005-06-23 00:07:54 -070056 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
Dave Hansen3a9da762005-06-23 00:07:42 -070062endchoice
63
Dave Hansene1785e82005-06-23 00:07:49 -070064config DISCONTIGMEM
65 def_bool y
66 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
67
Andy Whitcroftd41dee32005-06-23 00:07:54 -070068config SPARSEMEM
69 def_bool y
Russell King1a83e172009-10-26 16:50:12 -070070 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
Andy Whitcroftd41dee32005-06-23 00:07:54 -070071
Dave Hansene1785e82005-06-23 00:07:49 -070072config FLATMEM
73 def_bool y
Andy Whitcroftd41dee32005-06-23 00:07:54 -070074 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
75
76config FLAT_NODE_MEM_MAP
77 def_bool y
78 depends on !SPARSEMEM
Dave Hansene1785e82005-06-23 00:07:49 -070079
Dave Hansen93b75042005-06-23 00:07:47 -070080#
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
Andy Whitcroftaf705362005-06-23 00:07:53 -070088
89config HAVE_MEMORY_PRESENT
90 def_bool y
Andy Whitcroftd41dee32005-06-23 00:07:54 -070091 depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
Bob Picco802f1922005-09-03 15:54:26 -070092
93#
Bob Picco3e347262005-09-03 15:54:28 -070094# SPARSEMEM_EXTREME (which is the default) does some bootmem
Matt LaPlante84eb8d02006-10-03 22:53:09 +020095# allocations when memory_present() is called. If this cannot
Bob Picco3e347262005-09-03 15:54:28 -070096# 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
Jan Beulich9ba16082008-10-15 22:01:38 -0700104 bool
Bob Picco3e347262005-09-03 15:54:28 -0700105
106#
Matt LaPlante44c09202006-10-03 22:34:14 +0200107# Architecture platforms which require a two level mem_section in SPARSEMEM
Bob Picco802f1922005-09-03 15:54:26 -0700108# must select this option. This is usually for architecture platforms with
109# an extremely sparse physical address space.
110#
Bob Picco3e347262005-09-03 15:54:28 -0700111config SPARSEMEM_EXTREME
112 def_bool y
113 depends on SPARSEMEM && !SPARSEMEM_STATIC
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700114
Andy Whitcroft29c71112007-10-16 01:24:14 -0700115config SPARSEMEM_VMEMMAP_ENABLE
Jan Beulich9ba16082008-10-15 22:01:38 -0700116 bool
Andy Whitcroft29c71112007-10-16 01:24:14 -0700117
Yinghai Lu9bdac912010-02-10 01:20:22 -0800118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119 def_bool y
120 depends on SPARSEMEM && X86_64
121
Andy Whitcroft29c71112007-10-16 01:24:14 -0700122config SPARSEMEM_VMEMMAP
Geoff Levanda5ee6da2007-12-17 16:19:53 -0800123 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.
Andy Whitcroft29c71112007-10-16 01:24:14 -0700130
Yinghai Lu95f72d12010-07-12 14:36:09 +1000131config HAVE_MEMBLOCK
Christoph Jaeger6341e622014-12-20 15:41:11 -0500132 bool
Yinghai Lu95f72d12010-07-12 14:36:09 +1000133
Tejun Heo7c0caeb2011-07-14 11:43:42 +0200134config HAVE_MEMBLOCK_NODE_MAP
Christoph Jaeger6341e622014-12-20 15:41:11 -0500135 bool
Tejun Heo7c0caeb2011-07-14 11:43:42 +0200136
Philipp Hachtmann70210ed2014-01-29 18:16:01 +0100137config HAVE_MEMBLOCK_PHYS_MAP
Christoph Jaeger6341e622014-12-20 15:41:11 -0500138 bool
Philipp Hachtmann70210ed2014-01-29 18:16:01 +0100139
Steve Capper2667f502014-10-09 15:29:14 -0700140config HAVE_GENERIC_RCU_GUP
Christoph Jaeger6341e622014-12-20 15:41:11 -0500141 bool
Steve Capper2667f502014-10-09 15:29:14 -0700142
Tejun Heoc378ddd2011-07-14 11:46:03 +0200143config ARCH_DISCARD_MEMBLOCK
Christoph Jaeger6341e622014-12-20 15:41:11 -0500144 bool
Tejun Heoc378ddd2011-07-14 11:46:03 +0200145
Sam Ravnborg66616722011-10-31 17:08:20 -0700146config NO_BOOTMEM
Christoph Jaeger6341e622014-12-20 15:41:11 -0500147 bool
Sam Ravnborg66616722011-10-31 17:08:20 -0700148
Minchan Kimee6f5092012-07-31 16:43:50 -0700149config MEMORY_ISOLATION
Christoph Jaeger6341e622014-12-20 15:41:11 -0500150 bool
Minchan Kimee6f5092012-07-31 16:43:50 -0700151
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800152config MOVABLE_NODE
Christoph Jaeger6341e622014-12-20 15:41:11 -0500153 bool "Enable to assign a node which has only movable memory"
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800154 depends on HAVE_MEMBLOCK
155 depends on NO_BOOTMEM
156 depends on X86_64
157 depends on NUMA
Tang Chenc2974052012-12-18 14:21:33 -0800158 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
Tang Chenc5320922013-11-12 15:08:10 -0800162 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.
Tang Chenc2974052012-12-18 14:21:33 -0800174
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.
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800177
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800178#
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
Dave Hansen3947be12005-10-29 18:16:54 -0700185# eventually, we can have this option just 'select SPARSEMEM'
186config MEMORY_HOTPLUG
187 bool "Allow for memory hot-add"
Keith Manntheyec69acb2006-09-30 23:27:05 -0700188 depends on SPARSEMEM || X86_64_ACPI_NUMA
Stephen Rothwell40b31362013-05-21 13:49:35 +1000189 depends on ARCH_ENABLE_MEMORY_HOTPLUG
Dave Hansen3947be12005-10-29 18:16:54 -0700190
Keith Manntheyec69acb2006-09-30 23:27:05 -0700191config MEMORY_HOTPLUG_SPARSE
192 def_bool y
193 depends on SPARSEMEM && MEMORY_HOTPLUG
194
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700195config MEMORY_HOTREMOVE
196 bool "Allow for memory hot remove"
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800197 select MEMORY_ISOLATION
Nathan Fontenotf7e33342013-09-27 10:18:09 -0500198 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700199 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
200 depends on MIGRATION
201
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700202# Heavily threaded applications may benefit from splitting the mm-wide
203# page_table_lock, so that faults on different parts of the user address
204# space can be handled with less contention: split it at this NR_CPUS.
205# Default to 4 for wider testing, though 8 might be more appropriate.
206# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800207# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800208# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700209#
210config SPLIT_PTLOCK_CPUS
211 int
Kirill A. Shutemov91645502014-04-07 15:37:14 -0700212 default "999999" if !MMU
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800213 default "999999" if ARM && !CPU_CACHE_VIPT
214 default "999999" if PARISC && !PA20
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700215 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800216
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800217config ARCH_ENABLE_SPLIT_PMD_PTLOCK
Christoph Jaeger6341e622014-12-20 15:41:11 -0500218 bool
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800219
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800220#
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700221# support for memory balloon
222config MEMORY_BALLOON
Christoph Jaeger6341e622014-12-20 15:41:11 -0500223 bool
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700224
225#
Rafael Aquini18468d92012-12-11 16:02:38 -0800226# support for memory balloon compaction
227config BALLOON_COMPACTION
228 bool "Allow for balloon memory compaction/migration"
229 def_bool y
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700230 depends on COMPACTION && MEMORY_BALLOON
Rafael Aquini18468d92012-12-11 16:02:38 -0800231 help
232 Memory fragmentation introduced by ballooning might reduce
233 significantly the number of 2MB contiguous memory blocks that can be
234 used within a guest, thus imposing performance penalties associated
235 with the reduced number of transparent huge pages that could be used
236 by the guest workload. Allowing the compaction & migration for memory
237 pages enlisted as being part of memory balloon devices avoids the
238 scenario aforementioned and helps improving memory defragmentation.
239
240#
Mel Gormane9e96b32010-05-24 14:32:21 -0700241# support for memory compaction
242config COMPACTION
243 bool "Allow for memory compaction"
Rik van Riel05106e62012-10-08 16:33:03 -0700244 def_bool y
Mel Gormane9e96b32010-05-24 14:32:21 -0700245 select MIGRATION
Andrea Arcangeli33a93872011-01-25 15:07:25 -0800246 depends on MMU
Mel Gormane9e96b32010-05-24 14:32:21 -0700247 help
248 Allows the compaction of memory for the allocation of huge pages.
249
250#
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800251# support for page migration
252#
253config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800254 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700255 def_bool y
Chen Gangde32a812013-09-12 15:14:08 -0700256 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
Christoph Lameterb20a3502006-03-22 00:09:12 -0800257 help
258 Allows the migration of the physical location of pages of processes
Mel Gormane9e96b32010-05-24 14:32:21 -0700259 while the virtual addresses are not changed. This is useful in
260 two situations. The first is on NUMA systems to put pages nearer
261 to the processors accessing. The second is when allocating huge
262 pages as migration can relocate pages to satisfy a huge page
263 allocation instead of reclaiming.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700264
Naoya Horiguchic177c812014-06-04 16:05:35 -0700265config ARCH_ENABLE_HUGEPAGE_MIGRATION
Christoph Jaeger6341e622014-12-20 15:41:11 -0500266 bool
Naoya Horiguchic177c812014-06-04 16:05:35 -0700267
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700268config PHYS_ADDR_T_64BIT
269 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
270
Christoph Lameter4b51d662007-02-10 01:43:10 -0800271config ZONE_DMA_FLAG
272 int
273 default "0" if !ZONE_DMA
274 default "1"
275
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700276config BOUNCE
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700277 bool "Enable bounce buffers"
278 default y
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700279 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700280 help
281 Enable bounce buffers for devices that cannot access
282 the full range of memory available to the CPU. Enabled
283 by default when ZONE_DMA or HIGHMEM is selected, but you
284 may say n to override this.
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700285
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800286# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
287# have more than 4GB of memory, but we don't currently use the IOTLB to present
288# a 32-bit address to OHCI. So we need to use a bounce pool instead.
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800289config NEED_BOUNCE_POOL
290 bool
Valentin Rothbergdebeb292015-07-23 13:18:06 +0200291 default y if TILE && USB_OHCI_HCD
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800292
Christoph Lameter6225e932007-05-06 14:49:50 -0700293config NR_QUICK
294 int
295 depends on QUICKLIST
Paul Mundt0176bd32010-01-05 12:35:00 +0900296 default "2" if AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700297 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700298
299config VIRT_TO_BUS
Stephen Rothwell4febd952013-03-07 15:48:16 +1100300 bool
301 help
302 An architecture should select this if it implements the
303 deprecated interface virt_to_bus(). All new architectures
304 should probably not select this.
305
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700306
307config MMU_NOTIFIER
308 bool
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500309 select SRCU
David Howellsfc4d5c22009-05-06 16:03:05 -0700310
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700311config KSM
312 bool "Enable KSM for page merging"
313 depends on MMU
314 help
315 Enable Kernel Samepage Merging: KSM periodically scans those areas
316 of an application's address space that an app has advised may be
317 mergeable. When it finds pages of identical content, it replaces
Hugh Dickinsd0f209f2009-12-14 17:59:34 -0800318 the many instances by a single page with that content, so
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700319 saving memory until one or another app needs to modify the content.
320 Recommended for use with KVM, or with other duplicative applications.
Hugh Dickinsc73602a2009-10-07 16:32:22 -0700321 See Documentation/vm/ksm.txt for more information: KSM is inactive
322 until a program has madvised that an area is MADV_MERGEABLE, and
323 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700324
Christoph Lametere0a94c22009-06-03 16:04:31 -0400325config DEFAULT_MMAP_MIN_ADDR
326 int "Low address space to protect from user allocation"
David Howells6e141542009-12-15 19:27:45 +0000327 depends on MMU
Christoph Lametere0a94c22009-06-03 16:04:31 -0400328 default 4096
329 help
330 This is the portion of low virtual memory which should be protected
331 from userspace allocation. Keeping a user from writing to low pages
332 can help reduce the impact of kernel NULL pointer bugs.
333
334 For most ia64, ppc64 and x86 users with lots of address space
335 a value of 65536 is reasonable and should cause no problems.
336 On arm and other archs it should not be higher than 32768.
Eric Paris788084a2009-07-31 12:54:11 -0400337 Programs which use vm86 functionality or have some need to map
338 this low address space will need CAP_SYS_RAWIO or disable this
339 protection by setting the value to 0.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400340
341 This value can be changed after boot using the
342 /proc/sys/vm/mmap_min_addr tunable.
343
Linus Torvaldsd949f362009-09-26 09:35:07 -0700344config ARCH_SUPPORTS_MEMORY_FAILURE
345 bool
Christoph Lametere0a94c22009-06-03 16:04:31 -0400346
Andi Kleen6a460792009-09-16 11:50:15 +0200347config MEMORY_FAILURE
348 depends on MMU
Linus Torvaldsd949f362009-09-26 09:35:07 -0700349 depends on ARCH_SUPPORTS_MEMORY_FAILURE
Andi Kleen6a460792009-09-16 11:50:15 +0200350 bool "Enable recovery from hardware memory errors"
Minchan Kimee6f5092012-07-31 16:43:50 -0700351 select MEMORY_ISOLATION
Xie XiuQi97f0b132015-06-24 16:57:36 -0700352 select RAS
Andi Kleen6a460792009-09-16 11:50:15 +0200353 help
354 Enables code to recover from some memory failures on systems
355 with MCA recovery. This allows a system to continue running
356 even when some of its memory has uncorrected errors. This requires
357 special hardware support and typically ECC memory.
358
Andi Kleencae681f2009-09-16 11:50:17 +0200359config HWPOISON_INJECT
Andi Kleen413f9ef2009-12-16 12:20:00 +0100360 tristate "HWPoison pages injector"
Andi Kleen27df5062009-12-21 19:56:42 +0100361 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100362 select PROC_PAGE_MONITOR
Andi Kleencae681f2009-09-16 11:50:17 +0200363
David Howellsfc4d5c22009-05-06 16:03:05 -0700364config NOMMU_INITIAL_TRIM_EXCESS
365 int "Turn on mmap() excess space trimming before booting"
366 depends on !MMU
367 default 1
368 help
369 The NOMMU mmap() frequently needs to allocate large contiguous chunks
370 of memory on which to store mappings, but it can only ask the system
371 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
372 more than it requires. To deal with this, mmap() is able to trim off
373 the excess and return it to the allocator.
374
375 If trimming is enabled, the excess is trimmed off and returned to the
376 system allocator, which can cause extra fragmentation, particularly
377 if there are a lot of transient processes.
378
379 If trimming is disabled, the excess is kept, but not used, which for
380 long-term mappings means that the space is wasted.
381
382 Trimming can be dynamically controlled through a sysctl option
383 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
384 excess pages there must be before trimming should occur, or zero if
385 no trimming is to occur.
386
387 This option specifies the initial value of this option. The default
388 of 1 says that all excess pages should be trimmed.
389
390 See Documentation/nommu-mmap.txt for more information.
Tejun Heobbddff02010-09-03 18:22:48 +0200391
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800392config TRANSPARENT_HUGEPAGE
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800393 bool "Transparent Hugepage Support"
Gerald Schaefer15626062012-10-08 16:30:04 -0700394 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
Andrea Arcangeli5d689242011-01-13 15:47:07 -0800395 select COMPACTION
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800396 help
397 Transparent Hugepages allows the kernel to use huge pages and
398 huge tlb transparently to the applications whenever possible.
399 This feature can improve computing performance to certain
400 applications by speeding up page faults during memory
401 allocation, by reducing the number of tlb misses and by speeding
402 up the pagetable walking.
403
404 If memory constrained on embedded, you may want to say N.
405
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800406choice
407 prompt "Transparent Hugepage Support sysfs defaults"
408 depends on TRANSPARENT_HUGEPAGE
409 default TRANSPARENT_HUGEPAGE_ALWAYS
410 help
411 Selects the sysfs defaults for Transparent Hugepage Support.
412
413 config TRANSPARENT_HUGEPAGE_ALWAYS
414 bool "always"
415 help
416 Enabling Transparent Hugepage always, can increase the
417 memory footprint of applications without a guaranteed
418 benefit but it will work automatically for all applications.
419
420 config TRANSPARENT_HUGEPAGE_MADVISE
421 bool "madvise"
422 help
423 Enabling Transparent Hugepage madvise, will only provide a
424 performance improvement benefit to the applications using
425 madvise(MADV_HUGEPAGE) but it won't risk to increase the
426 memory footprint of applications without a guaranteed
427 benefit.
428endchoice
429
Tejun Heobbddff02010-09-03 18:22:48 +0200430#
431# UP and nommu archs use km based percpu allocator
432#
433config NEED_PER_CPU_KM
434 depends on !SMP
435 bool
436 default y
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600437
438config CLEANCACHE
439 bool "Enable cleancache driver to cache clean pages if tmem is present"
440 default n
441 help
442 Cleancache can be thought of as a page-granularity victim cache
443 for clean pages that the kernel's pageframe replacement algorithm
444 (PFRA) would like to keep around, but can't since there isn't enough
445 memory. So when the PFRA "evicts" a page, it first attempts to use
Michael Witten140a1ef2011-06-10 03:57:26 +0000446 cleancache code to put the data contained in that page into
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600447 "transcendent memory", memory that is not directly accessible or
448 addressable by the kernel and is of unknown and possibly
449 time-varying size. And when a cleancache-enabled
450 filesystem wishes to access a page in a file on disk, it first
451 checks cleancache to see if it already contains it; if it does,
452 the page is copied into the kernel and a disk access is avoided.
453 When a transcendent memory driver is available (such as zcache or
454 Xen transcendent memory), a significant I/O reduction
455 may be achieved. When none is available, all cleancache calls
456 are reduced to a single pointer-compare-against-NULL resulting
457 in a negligible performance hit.
458
459 If unsure, say Y to enable cleancache
Dan Magenheimer27c6aec2012-04-09 17:10:34 -0600460
461config FRONTSWAP
462 bool "Enable frontswap to cache swap pages if tmem is present"
463 depends on SWAP
464 default n
465 help
466 Frontswap is so named because it can be thought of as the opposite
467 of a "backing" store for a swap device. The data is stored into
468 "transcendent memory", memory that is not directly accessible or
469 addressable by the kernel and is of unknown and possibly
470 time-varying size. When space in transcendent memory is available,
471 a significant swap I/O reduction may be achieved. When none is
472 available, all frontswap calls are reduced to a single pointer-
473 compare-against-NULL resulting in a negligible performance hit
474 and swap data is stored as normal on the matching swap device.
475
476 If unsure, say Y to enable frontswap.
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530477
478config CMA
479 bool "Contiguous Memory Allocator"
Chen Gangde32a812013-09-12 15:14:08 -0700480 depends on HAVE_MEMBLOCK && MMU
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530481 select MIGRATION
482 select MEMORY_ISOLATION
483 help
484 This enables the Contiguous Memory Allocator which allows other
485 subsystems to allocate big physically-contiguous blocks of memory.
486 CMA reserves a region of memory and allows only movable pages to
487 be allocated from it. This way, the kernel can use the memory for
488 pagecache and when a subsystem requests for contiguous area, the
489 allocated pages are migrated away to serve the contiguous request.
490
491 If unsure, say "n".
492
493config CMA_DEBUG
494 bool "CMA debug messages (DEVELOPMENT)"
495 depends on DEBUG_KERNEL && CMA
496 help
497 Turns on debug messages in CMA. This produces KERN_DEBUG
498 messages for every CMA call as well as various messages while
499 processing calls such as dma_alloc_from_contiguous().
500 This option does not affect warning and error messages.
Alexander Grafbf550fc2013-08-29 00:41:59 +0200501
Sasha Levin28b24c12015-04-14 15:44:57 -0700502config CMA_DEBUGFS
503 bool "CMA debugfs interface"
504 depends on CMA && DEBUG_FS
505 help
506 Turns on the DebugFS interface for CMA.
507
Joonsoo Kima2541292014-08-06 16:05:25 -0700508config CMA_AREAS
509 int "Maximum count of the CMA areas"
510 depends on CMA
511 default 7
512 help
513 CMA allows to create CMA areas for particular purpose, mainly,
514 used as device private area. This parameter sets the maximum
515 number of CMA area in the system.
516
517 If unsure, leave the default value "7".
518
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700519config MEM_SOFT_DIRTY
520 bool "Track memory changes"
521 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
522 select PROC_PAGE_MONITOR
Seth Jennings4e2e2772013-07-10 16:04:55 -0700523 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700524 This option enables memory changes tracking by introducing a
525 soft-dirty bit on pte-s. This bit it set when someone writes
526 into a page just as regular dirty bit, but unlike the latter
527 it can be cleared by hands.
528
529 See Documentation/vm/soft-dirty.txt for more details.
Seth Jennings4e2e2772013-07-10 16:04:55 -0700530
Seth Jennings2b281112013-07-10 16:05:03 -0700531config ZSWAP
532 bool "Compressed cache for swap pages (EXPERIMENTAL)"
533 depends on FRONTSWAP && CRYPTO=y
534 select CRYPTO_LZO
Dan Streetman12d79d62014-08-06 16:08:40 -0700535 select ZPOOL
Seth Jennings2b281112013-07-10 16:05:03 -0700536 default n
537 help
538 A lightweight compressed cache for swap pages. It takes
539 pages that are in the process of being swapped out and attempts to
540 compress them into a dynamically allocated RAM-based memory pool.
541 This can result in a significant I/O reduction on swap device and,
542 in the case where decompressing from RAM is faster that swap device
543 reads, can also improve workload performance.
544
545 This is marked experimental because it is a new feature (as of
546 v3.11) that interacts heavily with memory reclaim. While these
547 interactions don't cause any known issues on simple memory setups,
548 they have not be fully explored on the large set of potential
549 configurations and workloads that exist.
550
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700551config ZPOOL
552 tristate "Common API for compressed memory storage"
553 default n
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700554 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700555 Compressed memory storage API. This allows using either zbud or
556 zsmalloc.
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700557
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700558config ZBUD
559 tristate "Low density storage for compressed pages"
560 default n
561 help
562 A special purpose allocator for storing compressed pages.
563 It is designed to store up to two compressed pages per physical
564 page. While this design limits storage density, it has simple and
565 deterministic reclaim properties that make it preferable to a higher
566 density approach when reclaim will be used.
Minchan Kimbcf16472014-01-30 15:45:50 -0800567
568config ZSMALLOC
Minchan Kimd867f202014-06-04 16:11:10 -0700569 tristate "Memory allocator for compressed pages"
Minchan Kimbcf16472014-01-30 15:45:50 -0800570 depends on MMU
571 default n
572 help
573 zsmalloc is a slab-based memory allocator designed to store
574 compressed RAM pages. zsmalloc uses virtual memory mapping
575 in order to reduce fragmentation. However, this results in a
576 non-standard allocator interface where a handle, not a pointer, is
577 returned by an alloc(). This handle must be mapped in order to
578 access the allocated space.
579
580config PGTABLE_MAPPING
581 bool "Use page table mapping to access object in zsmalloc"
582 depends on ZSMALLOC
583 help
584 By default, zsmalloc uses a copy-based object mapping method to
585 access allocations that span two pages. However, if a particular
586 architecture (ex, ARM) performs VM mapping faster than copying,
587 then you should select this. This causes zsmalloc to use page table
588 mapping rather than copying for object mapping.
589
Ben Hutchings2216ee82014-03-10 15:49:46 -0700590 You can check speed with zsmalloc benchmark:
591 https://github.com/spartacus06/zsmapbench
Mark Salter9e5c33d2014-04-07 15:39:48 -0700592
Ganesh Mahendran0f050d92015-02-12 15:00:54 -0800593config ZSMALLOC_STAT
594 bool "Export zsmalloc statistics"
595 depends on ZSMALLOC
596 select DEBUG_FS
597 help
598 This option enables code in the zsmalloc to collect various
599 statistics about whats happening in zsmalloc and exports that
600 information to userspace via debugfs.
601 If unsure, say N.
602
Mark Salter9e5c33d2014-04-07 15:39:48 -0700603config GENERIC_EARLY_IOREMAP
604 bool
Helge Deller042d27a2014-04-30 23:26:02 +0200605
606config MAX_STACK_SIZE_MB
607 int "Maximum user stack size for 32-bit processes (MB)"
608 default 80
609 range 8 256 if METAG
610 range 8 2048
611 depends on STACK_GROWSUP && (!64BIT || COMPAT)
612 help
613 This is the maximum stack size in Megabytes in the VM layout of 32-bit
614 user processes when the stack grows upwards (currently only on parisc
615 and metag arch). The stack will be located at the highest memory
616 address minus the given value, unless the RLIMIT_STACK hard limit is
617 changed to a smaller value in which case that is used.
618
619 A sane initial value is 80 MB.
Mel Gorman3a80a7f2015-06-30 14:57:02 -0700620
621# For architectures that support deferred memory initialisation
622config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
623 bool
624
625config DEFERRED_STRUCT_PAGE_INIT
Vlastimil Babka1ce22102016-02-05 15:36:21 -0800626 bool "Defer initialisation of struct pages to kthreads"
Mel Gorman3a80a7f2015-06-30 14:57:02 -0700627 default n
628 depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
629 depends on MEMORY_HOTPLUG
630 help
631 Ordinarily all struct pages are initialised during early boot in a
632 single thread. On very large machines this can take a considerable
633 amount of time. If this option is set, large machines will bring up
634 a subset of memmap at boot and then initialise the rest in parallel
Vlastimil Babka1ce22102016-02-05 15:36:21 -0800635 by starting one-off "pgdatinitX" kernel thread for each node X. This
636 has a potential performance impact on processes running early in the
637 lifetime of the system until these kthreads finish the
638 initialisation.
Dan Williams033fbae2015-08-09 15:29:06 -0400639
Vladimir Davydov33c3fc72015-09-09 15:35:45 -0700640config 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
Dan Williams033fbae2015-08-09 15:29:06 -0400652config ZONE_DEVICE
653 bool "Device memory (pmem, etc...) hotplug support" if EXPERT
Dan Williams033fbae2015-08-09 15:29:06 -0400654 depends on MEMORY_HOTPLUG
655 depends on MEMORY_HOTREMOVE
Dan Williams99490f12016-03-17 14:19:58 -0700656 depends on SPARSEMEM_VMEMMAP
Dan Williams033fbae2015-08-09 15:29:06 -0400657 depends on X86_64 #arch_add_memory() comprehends device memory
658
659 help
660 Device memory hotplug support allows for establishing pmem,
661 or other device driver discovered memory regions, in the
662 memmap. This allows pfn_to_page() lookups of otherwise
663 "device-physical" addresses which is needed for using a DAX
664 mapping in an O_DIRECT operation, among other things.
665
666 If FS_DAX is enabled, then say Y.
Linus Torvalds06a660a2015-09-11 16:42:39 -0700667
Jan Kara8025e5d2015-07-13 11:55:44 -0300668config FRAME_VECTOR
669 bool
Dave Hansen63c17fb2016-02-12 13:02:08 -0800670
671config ARCH_USES_HIGH_VMA_FLAGS
672 bool
Dave Hansen66d37572016-02-12 13:02:32 -0800673config ARCH_HAS_PKEYS
674 bool