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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
Tejun Heoc378ddd2011-07-14 11:46:03 +0200137config ARCH_DISCARD_MEMBLOCK
138 boolean
139
Sam Ravnborg66616722011-10-31 17:08:20 -0700140config NO_BOOTMEM
141 boolean
142
Minchan Kimee6f5092012-07-31 16:43:50 -0700143config MEMORY_ISOLATION
144 boolean
145
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800146config MOVABLE_NODE
147 boolean "Enable to assign a node which has only movable memory"
148 depends on HAVE_MEMBLOCK
149 depends on NO_BOOTMEM
150 depends on X86_64
151 depends on NUMA
Tang Chenc2974052012-12-18 14:21:33 -0800152 default n
153 help
154 Allow a node to have only movable memory. Pages used by the kernel,
155 such as direct mapping pages cannot be migrated. So the corresponding
Tang Chenc5320922013-11-12 15:08:10 -0800156 memory device cannot be hotplugged. This option allows the following
157 two things:
158 - When the system is booting, node full of hotpluggable memory can
159 be arranged to have only movable memory so that the whole node can
160 be hot-removed. (need movable_node boot option specified).
161 - After the system is up, the option allows users to online all the
162 memory of a node as movable memory so that the whole node can be
163 hot-removed.
164
165 Users who don't use the memory hotplug feature are fine with this
166 option on since they don't specify movable_node boot option or they
167 don't online memory as movable.
Tang Chenc2974052012-12-18 14:21:33 -0800168
169 Say Y here if you want to hotplug a whole node.
170 Say N here if you want kernel to use memory on all nodes evenly.
Lai Jiangshan20b2f522012-12-12 13:52:00 -0800171
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800172#
173# Only be set on architectures that have completely implemented memory hotplug
174# feature. If you are not sure, don't touch it.
175#
176config HAVE_BOOTMEM_INFO_NODE
177 def_bool n
178
Dave Hansen3947be12005-10-29 18:16:54 -0700179# eventually, we can have this option just 'select SPARSEMEM'
180config MEMORY_HOTPLUG
181 bool "Allow for memory hot-add"
Keith Manntheyec69acb2006-09-30 23:27:05 -0700182 depends on SPARSEMEM || X86_64_ACPI_NUMA
Stephen Rothwell40b31362013-05-21 13:49:35 +1000183 depends on ARCH_ENABLE_MEMORY_HOTPLUG
Kumar Galaed84a072009-10-16 07:21:36 +0000184 depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
Dave Hansen3947be12005-10-29 18:16:54 -0700185
Keith Manntheyec69acb2006-09-30 23:27:05 -0700186config MEMORY_HOTPLUG_SPARSE
187 def_bool y
188 depends on SPARSEMEM && MEMORY_HOTPLUG
189
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700190config MEMORY_HOTREMOVE
191 bool "Allow for memory hot remove"
Yasuaki Ishimatsu46723bf2013-02-22 16:33:00 -0800192 select MEMORY_ISOLATION
Nathan Fontenotf7e33342013-09-27 10:18:09 -0500193 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700194 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
195 depends on MIGRATION
196
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700197#
198# If we have space for more page flags then we can enable additional
199# optimizations and functionality.
200#
201# Regular Sparsemem takes page flag bits for the sectionid if it does not
202# use a virtual memmap. Disable extended page flags for 32 bit platforms
203# that require the use of a sectionid in the page flags.
204#
205config PAGEFLAGS_EXTENDED
206 def_bool y
H. Peter Anvina269cca2009-08-31 11:17:44 -0700207 depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700208
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700209# Heavily threaded applications may benefit from splitting the mm-wide
210# page_table_lock, so that faults on different parts of the user address
211# space can be handled with less contention: split it at this NR_CPUS.
212# Default to 4 for wider testing, though 8 might be more appropriate.
213# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800214# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800215# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700216#
217config SPLIT_PTLOCK_CPUS
218 int
Kirill A. Shutemov91645502014-04-07 15:37:14 -0700219 default "999999" if !MMU
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800220 default "999999" if ARM && !CPU_CACHE_VIPT
221 default "999999" if PARISC && !PA20
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700222 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800223
Kirill A. Shutemove009bb32013-11-14 14:31:07 -0800224config ARCH_ENABLE_SPLIT_PMD_PTLOCK
225 boolean
226
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800227#
Rafael Aquini18468d92012-12-11 16:02:38 -0800228# support for memory balloon compaction
229config BALLOON_COMPACTION
230 bool "Allow for balloon memory compaction/migration"
231 def_bool y
232 depends on COMPACTION && VIRTIO_BALLOON
233 help
234 Memory fragmentation introduced by ballooning might reduce
235 significantly the number of 2MB contiguous memory blocks that can be
236 used within a guest, thus imposing performance penalties associated
237 with the reduced number of transparent huge pages that could be used
238 by the guest workload. Allowing the compaction & migration for memory
239 pages enlisted as being part of memory balloon devices avoids the
240 scenario aforementioned and helps improving memory defragmentation.
241
242#
Mel Gormane9e96b32010-05-24 14:32:21 -0700243# support for memory compaction
244config COMPACTION
245 bool "Allow for memory compaction"
Rik van Riel05106e62012-10-08 16:33:03 -0700246 def_bool y
Mel Gormane9e96b32010-05-24 14:32:21 -0700247 select MIGRATION
Andrea Arcangeli33a93872011-01-25 15:07:25 -0800248 depends on MMU
Mel Gormane9e96b32010-05-24 14:32:21 -0700249 help
250 Allows the compaction of memory for the allocation of huge pages.
251
252#
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800253# support for page migration
254#
255config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800256 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700257 def_bool y
Chen Gangde32a812013-09-12 15:14:08 -0700258 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
Christoph Lameterb20a3502006-03-22 00:09:12 -0800259 help
260 Allows the migration of the physical location of pages of processes
Mel Gormane9e96b32010-05-24 14:32:21 -0700261 while the virtual addresses are not changed. This is useful in
262 two situations. The first is on NUMA systems to put pages nearer
263 to the processors accessing. The second is when allocating huge
264 pages as migration can relocate pages to satisfy a huge page
265 allocation instead of reclaiming.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700266
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700267config PHYS_ADDR_T_64BIT
268 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
269
Christoph Lameter4b51d662007-02-10 01:43:10 -0800270config ZONE_DMA_FLAG
271 int
272 default "0" if !ZONE_DMA
273 default "1"
274
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700275config BOUNCE
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700276 bool "Enable bounce buffers"
277 default y
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700278 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
Vinayak Menon9ca24e22013-04-29 15:08:55 -0700279 help
280 Enable bounce buffers for devices that cannot access
281 the full range of memory available to the CPU. Enabled
282 by default when ZONE_DMA or HIGHMEM is selected, but you
283 may say n to override this.
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700284
Darrick J. Wongffecfd12013-02-21 16:42:55 -0800285# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
286# have more than 4GB of memory, but we don't currently use the IOTLB to present
287# a 32-bit address to OHCI. So we need to use a bounce pool instead.
288#
289# We also use the bounce pool to provide stable page writes for jbd. jbd
290# initiates buffer writeback without locking the page or setting PG_writeback,
291# and fixing that behavior (a second time; jbd2 doesn't have this problem) is
292# a major rework effort. Instead, use the bounce buffer to snapshot pages
293# (until jbd goes away). The only jbd user is ext3.
294config NEED_BOUNCE_POOL
295 bool
296 default y if (TILE && USB_OHCI_HCD) || (BLK_DEV_INTEGRITY && JBD)
297
Christoph Lameter6225e932007-05-06 14:49:50 -0700298config NR_QUICK
299 int
300 depends on QUICKLIST
Paul Mundt0176bd32010-01-05 12:35:00 +0900301 default "2" if AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700302 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700303
304config VIRT_TO_BUS
Stephen Rothwell4febd952013-03-07 15:48:16 +1100305 bool
306 help
307 An architecture should select this if it implements the
308 deprecated interface virt_to_bus(). All new architectures
309 should probably not select this.
310
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700311
312config MMU_NOTIFIER
313 bool
David Howellsfc4d5c22009-05-06 16:03:05 -0700314
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700315config KSM
316 bool "Enable KSM for page merging"
317 depends on MMU
318 help
319 Enable Kernel Samepage Merging: KSM periodically scans those areas
320 of an application's address space that an app has advised may be
321 mergeable. When it finds pages of identical content, it replaces
Hugh Dickinsd0f209f2009-12-14 17:59:34 -0800322 the many instances by a single page with that content, so
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700323 saving memory until one or another app needs to modify the content.
324 Recommended for use with KVM, or with other duplicative applications.
Hugh Dickinsc73602a2009-10-07 16:32:22 -0700325 See Documentation/vm/ksm.txt for more information: KSM is inactive
326 until a program has madvised that an area is MADV_MERGEABLE, and
327 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700328
Christoph Lametere0a94c22009-06-03 16:04:31 -0400329config DEFAULT_MMAP_MIN_ADDR
330 int "Low address space to protect from user allocation"
David Howells6e141542009-12-15 19:27:45 +0000331 depends on MMU
Christoph Lametere0a94c22009-06-03 16:04:31 -0400332 default 4096
333 help
334 This is the portion of low virtual memory which should be protected
335 from userspace allocation. Keeping a user from writing to low pages
336 can help reduce the impact of kernel NULL pointer bugs.
337
338 For most ia64, ppc64 and x86 users with lots of address space
339 a value of 65536 is reasonable and should cause no problems.
340 On arm and other archs it should not be higher than 32768.
Eric Paris788084a2009-07-31 12:54:11 -0400341 Programs which use vm86 functionality or have some need to map
342 this low address space will need CAP_SYS_RAWIO or disable this
343 protection by setting the value to 0.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400344
345 This value can be changed after boot using the
346 /proc/sys/vm/mmap_min_addr tunable.
347
Linus Torvaldsd949f362009-09-26 09:35:07 -0700348config ARCH_SUPPORTS_MEMORY_FAILURE
349 bool
Christoph Lametere0a94c22009-06-03 16:04:31 -0400350
Andi Kleen6a460792009-09-16 11:50:15 +0200351config MEMORY_FAILURE
352 depends on MMU
Linus Torvaldsd949f362009-09-26 09:35:07 -0700353 depends on ARCH_SUPPORTS_MEMORY_FAILURE
Andi Kleen6a460792009-09-16 11:50:15 +0200354 bool "Enable recovery from hardware memory errors"
Minchan Kimee6f5092012-07-31 16:43:50 -0700355 select MEMORY_ISOLATION
Andi Kleen6a460792009-09-16 11:50:15 +0200356 help
357 Enables code to recover from some memory failures on systems
358 with MCA recovery. This allows a system to continue running
359 even when some of its memory has uncorrected errors. This requires
360 special hardware support and typically ECC memory.
361
Andi Kleencae681f2009-09-16 11:50:17 +0200362config HWPOISON_INJECT
Andi Kleen413f9ef2009-12-16 12:20:00 +0100363 tristate "HWPoison pages injector"
Andi Kleen27df5062009-12-21 19:56:42 +0100364 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100365 select PROC_PAGE_MONITOR
Andi Kleencae681f2009-09-16 11:50:17 +0200366
David Howellsfc4d5c22009-05-06 16:03:05 -0700367config NOMMU_INITIAL_TRIM_EXCESS
368 int "Turn on mmap() excess space trimming before booting"
369 depends on !MMU
370 default 1
371 help
372 The NOMMU mmap() frequently needs to allocate large contiguous chunks
373 of memory on which to store mappings, but it can only ask the system
374 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
375 more than it requires. To deal with this, mmap() is able to trim off
376 the excess and return it to the allocator.
377
378 If trimming is enabled, the excess is trimmed off and returned to the
379 system allocator, which can cause extra fragmentation, particularly
380 if there are a lot of transient processes.
381
382 If trimming is disabled, the excess is kept, but not used, which for
383 long-term mappings means that the space is wasted.
384
385 Trimming can be dynamically controlled through a sysctl option
386 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
387 excess pages there must be before trimming should occur, or zero if
388 no trimming is to occur.
389
390 This option specifies the initial value of this option. The default
391 of 1 says that all excess pages should be trimmed.
392
393 See Documentation/nommu-mmap.txt for more information.
Tejun Heobbddff02010-09-03 18:22:48 +0200394
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800395config TRANSPARENT_HUGEPAGE
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800396 bool "Transparent Hugepage Support"
Gerald Schaefer15626062012-10-08 16:30:04 -0700397 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
Andrea Arcangeli5d689242011-01-13 15:47:07 -0800398 select COMPACTION
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800399 help
400 Transparent Hugepages allows the kernel to use huge pages and
401 huge tlb transparently to the applications whenever possible.
402 This feature can improve computing performance to certain
403 applications by speeding up page faults during memory
404 allocation, by reducing the number of tlb misses and by speeding
405 up the pagetable walking.
406
407 If memory constrained on embedded, you may want to say N.
408
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800409choice
410 prompt "Transparent Hugepage Support sysfs defaults"
411 depends on TRANSPARENT_HUGEPAGE
412 default TRANSPARENT_HUGEPAGE_ALWAYS
413 help
414 Selects the sysfs defaults for Transparent Hugepage Support.
415
416 config TRANSPARENT_HUGEPAGE_ALWAYS
417 bool "always"
418 help
419 Enabling Transparent Hugepage always, can increase the
420 memory footprint of applications without a guaranteed
421 benefit but it will work automatically for all applications.
422
423 config TRANSPARENT_HUGEPAGE_MADVISE
424 bool "madvise"
425 help
426 Enabling Transparent Hugepage madvise, will only provide a
427 performance improvement benefit to the applications using
428 madvise(MADV_HUGEPAGE) but it won't risk to increase the
429 memory footprint of applications without a guaranteed
430 benefit.
431endchoice
432
Christopher Yeoh5febcbe2012-05-29 15:06:27 -0700433config CROSS_MEMORY_ATTACH
434 bool "Cross Memory Support"
435 depends on MMU
436 default y
437 help
438 Enabling this option adds the system calls process_vm_readv and
439 process_vm_writev which allow a process with the correct privileges
440 to directly read from or write to to another process's address space.
441 See the man page for more details.
442
Tejun Heobbddff02010-09-03 18:22:48 +0200443#
444# UP and nommu archs use km based percpu allocator
445#
446config NEED_PER_CPU_KM
447 depends on !SMP
448 bool
449 default y
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600450
451config CLEANCACHE
452 bool "Enable cleancache driver to cache clean pages if tmem is present"
453 default n
454 help
455 Cleancache can be thought of as a page-granularity victim cache
456 for clean pages that the kernel's pageframe replacement algorithm
457 (PFRA) would like to keep around, but can't since there isn't enough
458 memory. So when the PFRA "evicts" a page, it first attempts to use
Michael Witten140a1ef2011-06-10 03:57:26 +0000459 cleancache code to put the data contained in that page into
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600460 "transcendent memory", memory that is not directly accessible or
461 addressable by the kernel and is of unknown and possibly
462 time-varying size. And when a cleancache-enabled
463 filesystem wishes to access a page in a file on disk, it first
464 checks cleancache to see if it already contains it; if it does,
465 the page is copied into the kernel and a disk access is avoided.
466 When a transcendent memory driver is available (such as zcache or
467 Xen transcendent memory), a significant I/O reduction
468 may be achieved. When none is available, all cleancache calls
469 are reduced to a single pointer-compare-against-NULL resulting
470 in a negligible performance hit.
471
472 If unsure, say Y to enable cleancache
Dan Magenheimer27c6aec2012-04-09 17:10:34 -0600473
474config FRONTSWAP
475 bool "Enable frontswap to cache swap pages if tmem is present"
476 depends on SWAP
477 default n
478 help
479 Frontswap is so named because it can be thought of as the opposite
480 of a "backing" store for a swap device. The data is stored into
481 "transcendent memory", memory that is not directly accessible or
482 addressable by the kernel and is of unknown and possibly
483 time-varying size. When space in transcendent memory is available,
484 a significant swap I/O reduction may be achieved. When none is
485 available, all frontswap calls are reduced to a single pointer-
486 compare-against-NULL resulting in a negligible performance hit
487 and swap data is stored as normal on the matching swap device.
488
489 If unsure, say Y to enable frontswap.
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530490
491config CMA
492 bool "Contiguous Memory Allocator"
Chen Gangde32a812013-09-12 15:14:08 -0700493 depends on HAVE_MEMBLOCK && MMU
Aneesh Kumar K.Vf825c732013-07-02 11:15:15 +0530494 select MIGRATION
495 select MEMORY_ISOLATION
496 help
497 This enables the Contiguous Memory Allocator which allows other
498 subsystems to allocate big physically-contiguous blocks of memory.
499 CMA reserves a region of memory and allows only movable pages to
500 be allocated from it. This way, the kernel can use the memory for
501 pagecache and when a subsystem requests for contiguous area, the
502 allocated pages are migrated away to serve the contiguous request.
503
504 If unsure, say "n".
505
506config CMA_DEBUG
507 bool "CMA debug messages (DEVELOPMENT)"
508 depends on DEBUG_KERNEL && CMA
509 help
510 Turns on debug messages in CMA. This produces KERN_DEBUG
511 messages for every CMA call as well as various messages while
512 processing calls such as dma_alloc_from_contiguous().
513 This option does not affect warning and error messages.
Alexander Grafbf550fc2013-08-29 00:41:59 +0200514
Seth Jennings4e2e2772013-07-10 16:04:55 -0700515config ZBUD
516 tristate
517 default n
518 help
519 A special purpose allocator for storing compressed pages.
520 It is designed to store up to two compressed pages per physical
521 page. While this design limits storage density, it has simple and
522 deterministic reclaim properties that make it preferable to a higher
523 density approach when reclaim will be used.
524
Seth Jennings2b281112013-07-10 16:05:03 -0700525config ZSWAP
526 bool "Compressed cache for swap pages (EXPERIMENTAL)"
527 depends on FRONTSWAP && CRYPTO=y
528 select CRYPTO_LZO
529 select ZBUD
530 default n
531 help
532 A lightweight compressed cache for swap pages. It takes
533 pages that are in the process of being swapped out and attempts to
534 compress them into a dynamically allocated RAM-based memory pool.
535 This can result in a significant I/O reduction on swap device and,
536 in the case where decompressing from RAM is faster that swap device
537 reads, can also improve workload performance.
538
539 This is marked experimental because it is a new feature (as of
540 v3.11) that interacts heavily with memory reclaim. While these
541 interactions don't cause any known issues on simple memory setups,
542 they have not be fully explored on the large set of potential
543 configurations and workloads that exist.
544
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700545config MEM_SOFT_DIRTY
546 bool "Track memory changes"
Sima Baymania844f382013-12-18 17:08:49 -0800547 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
Pavel Emelyanov0f8975e2013-07-03 15:01:20 -0700548 select PROC_PAGE_MONITOR
549 help
550 This option enables memory changes tracking by introducing a
551 soft-dirty bit on pte-s. This bit it set when someone writes
552 into a page just as regular dirty bit, but unlike the latter
553 it can be cleared by hands.
554
555 See Documentation/vm/soft-dirty.txt for more details.
Minchan Kimbcf16472014-01-30 15:45:50 -0800556
557config ZSMALLOC
558 bool "Memory allocator for compressed pages"
559 depends on MMU
560 default n
561 help
562 zsmalloc is a slab-based memory allocator designed to store
563 compressed RAM pages. zsmalloc uses virtual memory mapping
564 in order to reduce fragmentation. However, this results in a
565 non-standard allocator interface where a handle, not a pointer, is
566 returned by an alloc(). This handle must be mapped in order to
567 access the allocated space.
568
569config PGTABLE_MAPPING
570 bool "Use page table mapping to access object in zsmalloc"
571 depends on ZSMALLOC
572 help
573 By default, zsmalloc uses a copy-based object mapping method to
574 access allocations that span two pages. However, if a particular
575 architecture (ex, ARM) performs VM mapping faster than copying,
576 then you should select this. This causes zsmalloc to use page table
577 mapping rather than copying for object mapping.
578
Ben Hutchings2216ee82014-03-10 15:49:46 -0700579 You can check speed with zsmalloc benchmark:
580 https://github.com/spartacus06/zsmapbench