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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
Kumar Galaed84a072009-10-16 07:21:36 +0000190 depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
Dave Hansen3947be12005-10-29 18:16:54 -0700191
Keith Manntheyec69acb2006-09-30 23:27:05 -0700192config MEMORY_HOTPLUG_SPARSE
193 def_bool y
194 depends on SPARSEMEM && MEMORY_HOTPLUG
195
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700196config MEMORY_HOTREMOVE
197 bool "Allow for memory hot remove"
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800198 select MEMORY_ISOLATION
Nathan Fontenotf7e33342013-09-27 10:18:09 -0500199 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700200 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
201 depends on MIGRATION
202
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700203# 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.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800208# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800209# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700210#
211config SPLIT_PTLOCK_CPUS
212 int
Kirill A. Shutemov91645502014-04-07 15:37:14 -0700213 default "999999" if !MMU
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800214 default "999999" if ARM && !CPU_CACHE_VIPT
215 default "999999" if PARISC && !PA20
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700216 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800217
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800218config ARCH_ENABLE_SPLIT_PMD_PTLOCK
Christoph Jaeger6341e622014-12-20 15:41:11 -0500219 bool
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800220
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800221#
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700222# support for memory balloon
223config MEMORY_BALLOON
Christoph Jaeger6341e622014-12-20 15:41:11 -0500224 bool
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700225
226#
Rafael Aquini18468d92012-12-11 16:02:38 -0800227# support for memory balloon compaction
228config BALLOON_COMPACTION
229 bool "Allow for balloon memory compaction/migration"
230 def_bool y
Konstantin Khlebnikov09316c02014-10-09 15:29:32 -0700231 depends on COMPACTION && MEMORY_BALLOON
Rafael Aquini18468d92012-12-11 16:02:38 -0800232 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#
Mel Gormane9e96b32010-05-24 14:32:21 -0700242# support for memory compaction
243config COMPACTION
244 bool "Allow for memory compaction"
Rik van Riel05106e62012-10-08 16:33:03 -0700245 def_bool y
Mel Gormane9e96b32010-05-24 14:32:21 -0700246 select MIGRATION
Andrea Arcangeli33a93872011-01-25 15:07:25 -0800247 depends on MMU
Mel Gormane9e96b32010-05-24 14:32:21 -0700248 help
249 Allows the compaction of memory for the allocation of huge pages.
250
251#
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800252# support for page migration
253#
254config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800255 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700256 def_bool y
Chen Gangde32a812013-09-12 15:14:08 -0700257 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
Christoph Lameterb20a3502006-03-22 00:09:12 -0800258 help
259 Allows the migration of the physical location of pages of processes
Mel Gormane9e96b32010-05-24 14:32:21 -0700260 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.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700265
Naoya Horiguchic177c812014-06-04 16:05:35 -0700266config ARCH_ENABLE_HUGEPAGE_MIGRATION
Christoph Jaeger6341e622014-12-20 15:41:11 -0500267 bool
Naoya Horiguchic177c812014-06-04 16:05:35 -0700268
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700269config PHYS_ADDR_T_64BIT
270 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
271
Christoph Lameter4b51d662007-02-10 01:43:10 -0800272config ZONE_DMA_FLAG
273 int
274 default "0" if !ZONE_DMA
275 default "1"
276
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700277config BOUNCE
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700278 bool "Enable bounce buffers"
279 default y
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700280 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700281 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.
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700286
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800287# 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.
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800290config NEED_BOUNCE_POOL
291 bool
Valentin Rothbergdebeb292015-07-23 13:18:06 +0200292 default y if TILE && USB_OHCI_HCD
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800293
Christoph Lameter6225e932007-05-06 14:49:50 -0700294config NR_QUICK
295 int
296 depends on QUICKLIST
Paul Mundt0176bd32010-01-05 12:35:00 +0900297 default "2" if AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700298 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700299
300config VIRT_TO_BUS
Stephen Rothwell4febd952013-03-07 15:48:16 +1100301 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
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700307
308config MMU_NOTIFIER
309 bool
Pranith Kumar83fe27e2014-12-05 11:24:45 -0500310 select SRCU
David Howellsfc4d5c22009-05-06 16:03:05 -0700311
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700312config 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
Hugh Dickinsd0f209f2009-12-14 17:59:34 -0800319 the many instances by a single page with that content, so
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700320 saving memory until one or another app needs to modify the content.
321 Recommended for use with KVM, or with other duplicative applications.
Hugh Dickinsc73602a2009-10-07 16:32:22 -0700322 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).
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700325
Christoph Lametere0a94c22009-06-03 16:04:31 -0400326config DEFAULT_MMAP_MIN_ADDR
327 int "Low address space to protect from user allocation"
David Howells6e141542009-12-15 19:27:45 +0000328 depends on MMU
Christoph Lametere0a94c22009-06-03 16:04:31 -0400329 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.
Eric Paris788084a2009-07-31 12:54:11 -0400338 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.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400341
342 This value can be changed after boot using the
343 /proc/sys/vm/mmap_min_addr tunable.
344
Linus Torvaldsd949f362009-09-26 09:35:07 -0700345config ARCH_SUPPORTS_MEMORY_FAILURE
346 bool
Christoph Lametere0a94c22009-06-03 16:04:31 -0400347
Andi Kleen6a460792009-09-16 11:50:15 +0200348config MEMORY_FAILURE
349 depends on MMU
Linus Torvaldsd949f362009-09-26 09:35:07 -0700350 depends on ARCH_SUPPORTS_MEMORY_FAILURE
Andi Kleen6a460792009-09-16 11:50:15 +0200351 bool "Enable recovery from hardware memory errors"
Minchan Kimee6f5092012-07-31 16:43:50 -0700352 select MEMORY_ISOLATION
Xie XiuQi97f0b132015-06-24 16:57:36 -0700353 select RAS
Andi Kleen6a460792009-09-16 11:50:15 +0200354 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
Andi Kleencae681f2009-09-16 11:50:17 +0200360config HWPOISON_INJECT
Andi Kleen413f9ef2009-12-16 12:20:00 +0100361 tristate "HWPoison pages injector"
Andi Kleen27df5062009-12-21 19:56:42 +0100362 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100363 select PROC_PAGE_MONITOR
Andi Kleencae681f2009-09-16 11:50:17 +0200364
David Howellsfc4d5c22009-05-06 16:03:05 -0700365config 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.
Tejun Heobbddff02010-09-03 18:22:48 +0200392
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800393config TRANSPARENT_HUGEPAGE
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800394 bool "Transparent Hugepage Support"
Gerald Schaefer15626062012-10-08 16:30:04 -0700395 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
Andrea Arcangeli5d689242011-01-13 15:47:07 -0800396 select COMPACTION
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800397 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
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800407choice
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
Tejun Heobbddff02010-09-03 18:22:48 +0200431#
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
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600438
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
Michael Witten140a1ef2011-06-10 03:57:26 +0000447 cleancache code to put the data contained in that page into
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600448 "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
Dan Magenheimer27c6aec2012-04-09 17:10:34 -0600461
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.
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530478
479config CMA
480 bool "Contiguous Memory Allocator"
Chen Gangde32a812013-09-12 15:14:08 -0700481 depends on HAVE_MEMBLOCK && MMU
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530482 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.
Alexander Grafbf550fc2013-08-29 00:41:59 +0200502
Sasha Levin28b24c12015-04-14 15:44:57 -0700503config CMA_DEBUGFS
504 bool "CMA debugfs interface"
505 depends on CMA && DEBUG_FS
506 help
507 Turns on the DebugFS interface for CMA.
508
Joonsoo Kima2541292014-08-06 16:05:25 -0700509config 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
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700520config MEM_SOFT_DIRTY
521 bool "Track memory changes"
522 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
523 select PROC_PAGE_MONITOR
Seth Jennings4e2e2772013-07-10 16:04:55 -0700524 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700525 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.
Seth Jennings4e2e2772013-07-10 16:04:55 -0700531
Seth Jennings2b281112013-07-10 16:05:03 -0700532config ZSWAP
533 bool "Compressed cache for swap pages (EXPERIMENTAL)"
534 depends on FRONTSWAP && CRYPTO=y
535 select CRYPTO_LZO
Dan Streetman12d79d62014-08-06 16:08:40 -0700536 select ZPOOL
Seth Jennings2b281112013-07-10 16:05:03 -0700537 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
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700552config ZPOOL
553 tristate "Common API for compressed memory storage"
554 default n
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700555 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700556 Compressed memory storage API. This allows using either zbud or
557 zsmalloc.
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700558
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700559config 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.
Minchan Kimbcf16472014-01-30 15:45:50 -0800568
569config ZSMALLOC
Minchan Kimd867f202014-06-04 16:11:10 -0700570 tristate "Memory allocator for compressed pages"
Minchan Kimbcf16472014-01-30 15:45:50 -0800571 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
Ben Hutchings2216ee82014-03-10 15:49:46 -0700591 You can check speed with zsmalloc benchmark:
592 https://github.com/spartacus06/zsmapbench
Mark Salter9e5c33d2014-04-07 15:39:48 -0700593
Ganesh Mahendran0f050d92015-02-12 15:00:54 -0800594config 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
Mark Salter9e5c33d2014-04-07 15:39:48 -0700604config GENERIC_EARLY_IOREMAP
605 bool
Helge Deller042d27a2014-04-30 23:26:02 +0200606
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.
Mel Gorman3a80a7f2015-06-30 14:57:02 -0700621
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.
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
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.
Linus Torvalds06a660a2015-09-11 16:42:39 -0700668
Jan Kara8025e5d2015-07-13 11:55:44 -0300669config FRAME_VECTOR
670 bool