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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
132 boolean
133
Tejun Heo7c0caeb2011-07-14 11:43:42 +0200134config HAVE_MEMBLOCK_NODE_MAP
135 boolean
136
Philipp Hachtmann70210ed2014-01-29 18:16:01 +0100137config HAVE_MEMBLOCK_PHYS_MAP
138 boolean
139
Tejun Heoc378ddd2011-07-14 11:46:03 +0200140config ARCH_DISCARD_MEMBLOCK
141 boolean
142
Sam Ravnborg66616722011-10-31 17:08:20 -0700143config NO_BOOTMEM
144 boolean
145
Minchan Kimee6f5092012-07-31 16:43:50 -0700146config MEMORY_ISOLATION
147 boolean
148
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800149config MOVABLE_NODE
150 boolean "Enable to assign a node which has only movable memory"
151 depends on HAVE_MEMBLOCK
152 depends on NO_BOOTMEM
153 depends on X86_64
154 depends on NUMA
Tang Chenc2974052012-12-18 14:21:33 -0800155 default n
156 help
157 Allow a node to have only movable memory. Pages used by the kernel,
158 such as direct mapping pages cannot be migrated. So the corresponding
Tang Chenc5320922013-11-12 15:08:10 -0800159 memory device cannot be hotplugged. This option allows the following
160 two things:
161 - When the system is booting, node full of hotpluggable memory can
162 be arranged to have only movable memory so that the whole node can
163 be hot-removed. (need movable_node boot option specified).
164 - After the system is up, the option allows users to online all the
165 memory of a node as movable memory so that the whole node can be
166 hot-removed.
167
168 Users who don't use the memory hotplug feature are fine with this
169 option on since they don't specify movable_node boot option or they
170 don't online memory as movable.
Tang Chenc2974052012-12-18 14:21:33 -0800171
172 Say Y here if you want to hotplug a whole node.
173 Say N here if you want kernel to use memory on all nodes evenly.
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800174
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800175#
176# Only be set on architectures that have completely implemented memory hotplug
177# feature. If you are not sure, don't touch it.
178#
179config HAVE_BOOTMEM_INFO_NODE
180 def_bool n
181
Dave Hansen3947be12005-10-29 18:16:54 -0700182# eventually, we can have this option just 'select SPARSEMEM'
183config MEMORY_HOTPLUG
184 bool "Allow for memory hot-add"
Keith Manntheyec69acb2006-09-30 23:27:05 -0700185 depends on SPARSEMEM || X86_64_ACPI_NUMA
Stephen Rothwell40b31362013-05-21 13:49:35 +1000186 depends on ARCH_ENABLE_MEMORY_HOTPLUG
Kumar Galaed84a072009-10-16 07:21:36 +0000187 depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
Dave Hansen3947be12005-10-29 18:16:54 -0700188
Keith Manntheyec69acb2006-09-30 23:27:05 -0700189config MEMORY_HOTPLUG_SPARSE
190 def_bool y
191 depends on SPARSEMEM && MEMORY_HOTPLUG
192
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700193config MEMORY_HOTREMOVE
194 bool "Allow for memory hot remove"
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800195 select MEMORY_ISOLATION
Nathan Fontenotf7e33342013-09-27 10:18:09 -0500196 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700197 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
198 depends on MIGRATION
199
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700200#
201# If we have space for more page flags then we can enable additional
202# optimizations and functionality.
203#
204# Regular Sparsemem takes page flag bits for the sectionid if it does not
205# use a virtual memmap. Disable extended page flags for 32 bit platforms
206# that require the use of a sectionid in the page flags.
207#
208config PAGEFLAGS_EXTENDED
209 def_bool y
H. Peter Anvina269cca2009-08-31 11:17:44 -0700210 depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700211
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700212# Heavily threaded applications may benefit from splitting the mm-wide
213# page_table_lock, so that faults on different parts of the user address
214# space can be handled with less contention: split it at this NR_CPUS.
215# Default to 4 for wider testing, though 8 might be more appropriate.
216# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800217# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800218# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700219#
220config SPLIT_PTLOCK_CPUS
221 int
Kirill A. Shutemov91645502014-04-07 15:37:14 -0700222 default "999999" if !MMU
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800223 default "999999" if ARM && !CPU_CACHE_VIPT
224 default "999999" if PARISC && !PA20
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700225 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800226
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800227config ARCH_ENABLE_SPLIT_PMD_PTLOCK
228 boolean
229
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800230#
Rafael Aquini18468d92012-12-11 16:02:38 -0800231# support for memory balloon compaction
232config BALLOON_COMPACTION
233 bool "Allow for balloon memory compaction/migration"
234 def_bool y
235 depends on COMPACTION && VIRTIO_BALLOON
236 help
237 Memory fragmentation introduced by ballooning might reduce
238 significantly the number of 2MB contiguous memory blocks that can be
239 used within a guest, thus imposing performance penalties associated
240 with the reduced number of transparent huge pages that could be used
241 by the guest workload. Allowing the compaction & migration for memory
242 pages enlisted as being part of memory balloon devices avoids the
243 scenario aforementioned and helps improving memory defragmentation.
244
245#
Mel Gormane9e96b32010-05-24 14:32:21 -0700246# support for memory compaction
247config COMPACTION
248 bool "Allow for memory compaction"
Rik van Riel05106e62012-10-08 16:33:03 -0700249 def_bool y
Mel Gormane9e96b32010-05-24 14:32:21 -0700250 select MIGRATION
Andrea Arcangeli33a93872011-01-25 15:07:25 -0800251 depends on MMU
Mel Gormane9e96b32010-05-24 14:32:21 -0700252 help
253 Allows the compaction of memory for the allocation of huge pages.
254
255#
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800256# support for page migration
257#
258config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800259 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700260 def_bool y
Chen Gangde32a812013-09-12 15:14:08 -0700261 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
Christoph Lameterb20a3502006-03-22 00:09:12 -0800262 help
263 Allows the migration of the physical location of pages of processes
Mel Gormane9e96b32010-05-24 14:32:21 -0700264 while the virtual addresses are not changed. This is useful in
265 two situations. The first is on NUMA systems to put pages nearer
266 to the processors accessing. The second is when allocating huge
267 pages as migration can relocate pages to satisfy a huge page
268 allocation instead of reclaiming.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700269
Naoya Horiguchic177c812014-06-04 16:05:35 -0700270config ARCH_ENABLE_HUGEPAGE_MIGRATION
271 boolean
272
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700273config PHYS_ADDR_T_64BIT
274 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
275
Christoph Lameter4b51d662007-02-10 01:43:10 -0800276config ZONE_DMA_FLAG
277 int
278 default "0" if !ZONE_DMA
279 default "1"
280
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700281config BOUNCE
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700282 bool "Enable bounce buffers"
283 default y
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700284 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700285 help
286 Enable bounce buffers for devices that cannot access
287 the full range of memory available to the CPU. Enabled
288 by default when ZONE_DMA or HIGHMEM is selected, but you
289 may say n to override this.
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700290
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800291# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
292# have more than 4GB of memory, but we don't currently use the IOTLB to present
293# a 32-bit address to OHCI. So we need to use a bounce pool instead.
294#
295# We also use the bounce pool to provide stable page writes for jbd. jbd
296# initiates buffer writeback without locking the page or setting PG_writeback,
297# and fixing that behavior (a second time; jbd2 doesn't have this problem) is
298# a major rework effort. Instead, use the bounce buffer to snapshot pages
299# (until jbd goes away). The only jbd user is ext3.
300config NEED_BOUNCE_POOL
301 bool
302 default y if (TILE && USB_OHCI_HCD) || (BLK_DEV_INTEGRITY && JBD)
303
Christoph Lameter6225e932007-05-06 14:49:50 -0700304config NR_QUICK
305 int
306 depends on QUICKLIST
Paul Mundt0176bd32010-01-05 12:35:00 +0900307 default "2" if AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700308 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700309
310config VIRT_TO_BUS
Stephen Rothwell4febd952013-03-07 15:48:16 +1100311 bool
312 help
313 An architecture should select this if it implements the
314 deprecated interface virt_to_bus(). All new architectures
315 should probably not select this.
316
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700317
318config MMU_NOTIFIER
319 bool
David Howellsfc4d5c22009-05-06 16:03:05 -0700320
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700321config KSM
322 bool "Enable KSM for page merging"
323 depends on MMU
324 help
325 Enable Kernel Samepage Merging: KSM periodically scans those areas
326 of an application's address space that an app has advised may be
327 mergeable. When it finds pages of identical content, it replaces
Hugh Dickinsd0f209f2009-12-14 17:59:34 -0800328 the many instances by a single page with that content, so
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700329 saving memory until one or another app needs to modify the content.
330 Recommended for use with KVM, or with other duplicative applications.
Hugh Dickinsc73602a2009-10-07 16:32:22 -0700331 See Documentation/vm/ksm.txt for more information: KSM is inactive
332 until a program has madvised that an area is MADV_MERGEABLE, and
333 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700334
Christoph Lametere0a94c22009-06-03 16:04:31 -0400335config DEFAULT_MMAP_MIN_ADDR
336 int "Low address space to protect from user allocation"
David Howells6e141542009-12-15 19:27:45 +0000337 depends on MMU
Christoph Lametere0a94c22009-06-03 16:04:31 -0400338 default 4096
339 help
340 This is the portion of low virtual memory which should be protected
341 from userspace allocation. Keeping a user from writing to low pages
342 can help reduce the impact of kernel NULL pointer bugs.
343
344 For most ia64, ppc64 and x86 users with lots of address space
345 a value of 65536 is reasonable and should cause no problems.
346 On arm and other archs it should not be higher than 32768.
Eric Paris788084a2009-07-31 12:54:11 -0400347 Programs which use vm86 functionality or have some need to map
348 this low address space will need CAP_SYS_RAWIO or disable this
349 protection by setting the value to 0.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400350
351 This value can be changed after boot using the
352 /proc/sys/vm/mmap_min_addr tunable.
353
Linus Torvaldsd949f362009-09-26 09:35:07 -0700354config ARCH_SUPPORTS_MEMORY_FAILURE
355 bool
Christoph Lametere0a94c22009-06-03 16:04:31 -0400356
Andi Kleen6a460792009-09-16 11:50:15 +0200357config MEMORY_FAILURE
358 depends on MMU
Linus Torvaldsd949f362009-09-26 09:35:07 -0700359 depends on ARCH_SUPPORTS_MEMORY_FAILURE
Andi Kleen6a460792009-09-16 11:50:15 +0200360 bool "Enable recovery from hardware memory errors"
Minchan Kimee6f5092012-07-31 16:43:50 -0700361 select MEMORY_ISOLATION
Andi Kleen6a460792009-09-16 11:50:15 +0200362 help
363 Enables code to recover from some memory failures on systems
364 with MCA recovery. This allows a system to continue running
365 even when some of its memory has uncorrected errors. This requires
366 special hardware support and typically ECC memory.
367
Andi Kleencae681f2009-09-16 11:50:17 +0200368config HWPOISON_INJECT
Andi Kleen413f9ef2009-12-16 12:20:00 +0100369 tristate "HWPoison pages injector"
Andi Kleen27df5062009-12-21 19:56:42 +0100370 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100371 select PROC_PAGE_MONITOR
Andi Kleencae681f2009-09-16 11:50:17 +0200372
David Howellsfc4d5c22009-05-06 16:03:05 -0700373config NOMMU_INITIAL_TRIM_EXCESS
374 int "Turn on mmap() excess space trimming before booting"
375 depends on !MMU
376 default 1
377 help
378 The NOMMU mmap() frequently needs to allocate large contiguous chunks
379 of memory on which to store mappings, but it can only ask the system
380 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
381 more than it requires. To deal with this, mmap() is able to trim off
382 the excess and return it to the allocator.
383
384 If trimming is enabled, the excess is trimmed off and returned to the
385 system allocator, which can cause extra fragmentation, particularly
386 if there are a lot of transient processes.
387
388 If trimming is disabled, the excess is kept, but not used, which for
389 long-term mappings means that the space is wasted.
390
391 Trimming can be dynamically controlled through a sysctl option
392 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
393 excess pages there must be before trimming should occur, or zero if
394 no trimming is to occur.
395
396 This option specifies the initial value of this option. The default
397 of 1 says that all excess pages should be trimmed.
398
399 See Documentation/nommu-mmap.txt for more information.
Tejun Heobbddff02010-09-03 18:22:48 +0200400
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800401config TRANSPARENT_HUGEPAGE
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800402 bool "Transparent Hugepage Support"
Gerald Schaefer15626062012-10-08 16:30:04 -0700403 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
Andrea Arcangeli5d689242011-01-13 15:47:07 -0800404 select COMPACTION
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800405 help
406 Transparent Hugepages allows the kernel to use huge pages and
407 huge tlb transparently to the applications whenever possible.
408 This feature can improve computing performance to certain
409 applications by speeding up page faults during memory
410 allocation, by reducing the number of tlb misses and by speeding
411 up the pagetable walking.
412
413 If memory constrained on embedded, you may want to say N.
414
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800415choice
416 prompt "Transparent Hugepage Support sysfs defaults"
417 depends on TRANSPARENT_HUGEPAGE
418 default TRANSPARENT_HUGEPAGE_ALWAYS
419 help
420 Selects the sysfs defaults for Transparent Hugepage Support.
421
422 config TRANSPARENT_HUGEPAGE_ALWAYS
423 bool "always"
424 help
425 Enabling Transparent Hugepage always, can increase the
426 memory footprint of applications without a guaranteed
427 benefit but it will work automatically for all applications.
428
429 config TRANSPARENT_HUGEPAGE_MADVISE
430 bool "madvise"
431 help
432 Enabling Transparent Hugepage madvise, will only provide a
433 performance improvement benefit to the applications using
434 madvise(MADV_HUGEPAGE) but it won't risk to increase the
435 memory footprint of applications without a guaranteed
436 benefit.
437endchoice
438
Tejun Heobbddff02010-09-03 18:22:48 +0200439#
440# UP and nommu archs use km based percpu allocator
441#
442config NEED_PER_CPU_KM
443 depends on !SMP
444 bool
445 default y
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600446
447config CLEANCACHE
448 bool "Enable cleancache driver to cache clean pages if tmem is present"
449 default n
450 help
451 Cleancache can be thought of as a page-granularity victim cache
452 for clean pages that the kernel's pageframe replacement algorithm
453 (PFRA) would like to keep around, but can't since there isn't enough
454 memory. So when the PFRA "evicts" a page, it first attempts to use
Michael Witten140a1ef2011-06-10 03:57:26 +0000455 cleancache code to put the data contained in that page into
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600456 "transcendent memory", memory that is not directly accessible or
457 addressable by the kernel and is of unknown and possibly
458 time-varying size. And when a cleancache-enabled
459 filesystem wishes to access a page in a file on disk, it first
460 checks cleancache to see if it already contains it; if it does,
461 the page is copied into the kernel and a disk access is avoided.
462 When a transcendent memory driver is available (such as zcache or
463 Xen transcendent memory), a significant I/O reduction
464 may be achieved. When none is available, all cleancache calls
465 are reduced to a single pointer-compare-against-NULL resulting
466 in a negligible performance hit.
467
468 If unsure, say Y to enable cleancache
Dan Magenheimer27c6aec2012-04-09 17:10:34 -0600469
470config FRONTSWAP
471 bool "Enable frontswap to cache swap pages if tmem is present"
472 depends on SWAP
473 default n
474 help
475 Frontswap is so named because it can be thought of as the opposite
476 of a "backing" store for a swap device. The data is stored into
477 "transcendent memory", memory that is not directly accessible or
478 addressable by the kernel and is of unknown and possibly
479 time-varying size. When space in transcendent memory is available,
480 a significant swap I/O reduction may be achieved. When none is
481 available, all frontswap calls are reduced to a single pointer-
482 compare-against-NULL resulting in a negligible performance hit
483 and swap data is stored as normal on the matching swap device.
484
485 If unsure, say Y to enable frontswap.
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530486
487config CMA
488 bool "Contiguous Memory Allocator"
Chen Gangde32a812013-09-12 15:14:08 -0700489 depends on HAVE_MEMBLOCK && MMU
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530490 select MIGRATION
491 select MEMORY_ISOLATION
492 help
493 This enables the Contiguous Memory Allocator which allows other
494 subsystems to allocate big physically-contiguous blocks of memory.
495 CMA reserves a region of memory and allows only movable pages to
496 be allocated from it. This way, the kernel can use the memory for
497 pagecache and when a subsystem requests for contiguous area, the
498 allocated pages are migrated away to serve the contiguous request.
499
500 If unsure, say "n".
501
502config CMA_DEBUG
503 bool "CMA debug messages (DEVELOPMENT)"
504 depends on DEBUG_KERNEL && CMA
505 help
506 Turns on debug messages in CMA. This produces KERN_DEBUG
507 messages for every CMA call as well as various messages while
508 processing calls such as dma_alloc_from_contiguous().
509 This option does not affect warning and error messages.
Alexander Grafbf550fc2013-08-29 00:41:59 +0200510
Joonsoo Kima2541292014-08-06 16:05:25 -0700511config CMA_AREAS
512 int "Maximum count of the CMA areas"
513 depends on CMA
514 default 7
515 help
516 CMA allows to create CMA areas for particular purpose, mainly,
517 used as device private area. This parameter sets the maximum
518 number of CMA area in the system.
519
520 If unsure, leave the default value "7".
521
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700522config MEM_SOFT_DIRTY
523 bool "Track memory changes"
524 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
525 select PROC_PAGE_MONITOR
Seth Jennings4e2e2772013-07-10 16:04:55 -0700526 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700527 This option enables memory changes tracking by introducing a
528 soft-dirty bit on pte-s. This bit it set when someone writes
529 into a page just as regular dirty bit, but unlike the latter
530 it can be cleared by hands.
531
532 See Documentation/vm/soft-dirty.txt for more details.
Seth Jennings4e2e2772013-07-10 16:04:55 -0700533
Seth Jennings2b281112013-07-10 16:05:03 -0700534config ZSWAP
535 bool "Compressed cache for swap pages (EXPERIMENTAL)"
536 depends on FRONTSWAP && CRYPTO=y
537 select CRYPTO_LZO
Dan Streetman12d79d62014-08-06 16:08:40 -0700538 select ZPOOL
Seth Jennings2b281112013-07-10 16:05:03 -0700539 default n
540 help
541 A lightweight compressed cache for swap pages. It takes
542 pages that are in the process of being swapped out and attempts to
543 compress them into a dynamically allocated RAM-based memory pool.
544 This can result in a significant I/O reduction on swap device and,
545 in the case where decompressing from RAM is faster that swap device
546 reads, can also improve workload performance.
547
548 This is marked experimental because it is a new feature (as of
549 v3.11) that interacts heavily with memory reclaim. While these
550 interactions don't cause any known issues on simple memory setups,
551 they have not be fully explored on the large set of potential
552 configurations and workloads that exist.
553
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700554config ZPOOL
555 tristate "Common API for compressed memory storage"
556 default n
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700557 help
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700558 Compressed memory storage API. This allows using either zbud or
559 zsmalloc.
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700560
Dan Streetmanaf8d4172014-08-06 16:08:36 -0700561config ZBUD
562 tristate "Low density storage for compressed pages"
563 default n
564 help
565 A special purpose allocator for storing compressed pages.
566 It is designed to store up to two compressed pages per physical
567 page. While this design limits storage density, it has simple and
568 deterministic reclaim properties that make it preferable to a higher
569 density approach when reclaim will be used.
Minchan Kimbcf16472014-01-30 15:45:50 -0800570
571config ZSMALLOC
Minchan Kimd867f202014-06-04 16:11:10 -0700572 tristate "Memory allocator for compressed pages"
Minchan Kimbcf16472014-01-30 15:45:50 -0800573 depends on MMU
574 default n
575 help
576 zsmalloc is a slab-based memory allocator designed to store
577 compressed RAM pages. zsmalloc uses virtual memory mapping
578 in order to reduce fragmentation. However, this results in a
579 non-standard allocator interface where a handle, not a pointer, is
580 returned by an alloc(). This handle must be mapped in order to
581 access the allocated space.
582
583config PGTABLE_MAPPING
584 bool "Use page table mapping to access object in zsmalloc"
585 depends on ZSMALLOC
586 help
587 By default, zsmalloc uses a copy-based object mapping method to
588 access allocations that span two pages. However, if a particular
589 architecture (ex, ARM) performs VM mapping faster than copying,
590 then you should select this. This causes zsmalloc to use page table
591 mapping rather than copying for object mapping.
592
Ben Hutchings2216ee82014-03-10 15:49:46 -0700593 You can check speed with zsmalloc benchmark:
594 https://github.com/spartacus06/zsmapbench
Mark Salter9e5c33d2014-04-07 15:39:48 -0700595
596config GENERIC_EARLY_IOREMAP
597 bool
Helge Deller042d27a2014-04-30 23:26:02 +0200598
599config MAX_STACK_SIZE_MB
600 int "Maximum user stack size for 32-bit processes (MB)"
601 default 80
602 range 8 256 if METAG
603 range 8 2048
604 depends on STACK_GROWSUP && (!64BIT || COMPAT)
605 help
606 This is the maximum stack size in Megabytes in the VM layout of 32-bit
607 user processes when the stack grows upwards (currently only on parisc
608 and metag arch). The stack will be located at the highest memory
609 address minus the given value, unless the RLIMIT_STACK hard limit is
610 changed to a smaller value in which case that is used.
611
612 A sane initial value is 80 MB.