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1config SELECT_MEMORY_MODEL
2 def_bool y
a8826eeb 3 depends on ARCH_SELECT_MEMORY_MODEL
e1785e85 4
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5choice
6 prompt "Memory model"
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7 depends on SELECT_MEMORY_MODEL
8 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
d41dee36 9 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
e1785e85 10 default FLATMEM_MANUAL
3a9da765 11
e1785e85 12config FLATMEM_MANUAL
3a9da765 13 bool "Flat Memory"
c898ec16 14 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
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15 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
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21 Some users of more advanced features like NUMA and
22 memory hotplug may have different options here.
18f65332 23 DISCONTIGMEM is a more mature, better tested system,
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24 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.
3a9da765 30
e1785e85 31config DISCONTIGMEM_MANUAL
f3519f91 32 bool "Discontiguous Memory"
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33 depends on ARCH_DISCONTIGMEM_ENABLE
34 help
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35 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
ad3d0a38 40 can have degraded performance from the extra overhead that
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41 this option imposes.
42
43 Many NUMA configurations will have this as the only option.
44
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45 If unsure, choose "Flat Memory" over this option.
46
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47config 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
f3519f91 55 "Discontiguous Memory". This option provides some potential
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56 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
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62endchoice
63
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64config DISCONTIGMEM
65 def_bool y
66 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
67
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68config SPARSEMEM
69 def_bool y
1a83e175 70 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
d41dee36 71
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72config FLATMEM
73 def_bool y
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74 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
75
76config FLAT_NODE_MEM_MAP
77 def_bool y
78 depends on !SPARSEMEM
e1785e85 79
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80#
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
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88
89config HAVE_MEMORY_PRESENT
90 def_bool y
d41dee36 91 depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
802f192e 92
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93#
94# SPARSEMEM_EXTREME (which is the default) does some bootmem
84eb8d06 95# allocations when memory_present() is called. If this cannot
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96# 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
9ba16087 104 bool
3e347261 105
802f192e 106#
44c09201 107# Architecture platforms which require a two level mem_section in SPARSEMEM
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108# must select this option. This is usually for architecture platforms with
109# an extremely sparse physical address space.
110#
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111config SPARSEMEM_EXTREME
112 def_bool y
113 depends on SPARSEMEM && !SPARSEMEM_STATIC
4c21e2f2 114
29c71111 115config SPARSEMEM_VMEMMAP_ENABLE
9ba16087 116 bool
29c71111 117
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118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119 def_bool y
120 depends on SPARSEMEM && X86_64
121
29c71111 122config SPARSEMEM_VMEMMAP
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123 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.
29c71111 130
95f72d1e 131config HAVE_MEMBLOCK
6341e62b 132 bool
95f72d1e 133
7c0caeb8 134config HAVE_MEMBLOCK_NODE_MAP
6341e62b 135 bool
7c0caeb8 136
70210ed9 137config HAVE_MEMBLOCK_PHYS_MAP
6341e62b 138 bool
70210ed9 139
2667f50e 140config HAVE_GENERIC_RCU_GUP
6341e62b 141 bool
2667f50e 142
c378ddd5 143config ARCH_DISCARD_MEMBLOCK
6341e62b 144 bool
c378ddd5 145
66616720 146config NO_BOOTMEM
6341e62b 147 bool
66616720 148
ee6f509c 149config MEMORY_ISOLATION
6341e62b 150 bool
ee6f509c 151
20b2f52b 152config MOVABLE_NODE
6341e62b 153 bool "Enable to assign a node which has only movable memory"
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154 depends on HAVE_MEMBLOCK
155 depends on NO_BOOTMEM
156 depends on X86_64
157 depends on NUMA
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158 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
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162 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.
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174
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.
20b2f52b 177
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178#
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
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185# eventually, we can have this option just 'select SPARSEMEM'
186config MEMORY_HOTPLUG
187 bool "Allow for memory hot-add"
ec69acbb 188 depends on SPARSEMEM || X86_64_ACPI_NUMA
40b31360 189 depends on ARCH_ENABLE_MEMORY_HOTPLUG
3947be19 190
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191config MEMORY_HOTPLUG_SPARSE
192 def_bool y
193 depends on SPARSEMEM && MEMORY_HOTPLUG
194
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195config MEMORY_HOTPLUG_DEFAULT_ONLINE
196 bool "Online the newly added memory blocks by default"
197 default n
198 depends on MEMORY_HOTPLUG
199 help
200 This option sets the default policy setting for memory hotplug
201 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
202 determines what happens to newly added memory regions. Policy setting
203 can always be changed at runtime.
204 See Documentation/memory-hotplug.txt for more information.
205
206 Say Y here if you want all hot-plugged memory blocks to appear in
207 'online' state by default.
208 Say N here if you want the default policy to keep all hot-plugged
209 memory blocks in 'offline' state.
210
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211config MEMORY_HOTREMOVE
212 bool "Allow for memory hot remove"
46723bfa 213 select MEMORY_ISOLATION
f7e3334a 214 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
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215 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
216 depends on MIGRATION
217
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218# Heavily threaded applications may benefit from splitting the mm-wide
219# page_table_lock, so that faults on different parts of the user address
220# space can be handled with less contention: split it at this NR_CPUS.
221# Default to 4 for wider testing, though 8 might be more appropriate.
222# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
7b6ac9df 223# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
a70caa8b 224# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
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225#
226config SPLIT_PTLOCK_CPUS
227 int
9164550e 228 default "999999" if !MMU
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229 default "999999" if ARM && !CPU_CACHE_VIPT
230 default "999999" if PARISC && !PA20
4c21e2f2 231 default "4"
7cbe34cf 232
e009bb30 233config ARCH_ENABLE_SPLIT_PMD_PTLOCK
6341e62b 234 bool
e009bb30 235
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236#
237# support for memory balloon
238config MEMORY_BALLOON
6341e62b 239 bool
09316c09 240
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241#
242# support for memory balloon compaction
243config BALLOON_COMPACTION
244 bool "Allow for balloon memory compaction/migration"
245 def_bool y
09316c09 246 depends on COMPACTION && MEMORY_BALLOON
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247 help
248 Memory fragmentation introduced by ballooning might reduce
249 significantly the number of 2MB contiguous memory blocks that can be
250 used within a guest, thus imposing performance penalties associated
251 with the reduced number of transparent huge pages that could be used
252 by the guest workload. Allowing the compaction & migration for memory
253 pages enlisted as being part of memory balloon devices avoids the
254 scenario aforementioned and helps improving memory defragmentation.
255
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256#
257# support for memory compaction
258config COMPACTION
259 bool "Allow for memory compaction"
05106e6a 260 def_bool y
e9e96b39 261 select MIGRATION
33a93877 262 depends on MMU
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263 help
264 Allows the compaction of memory for the allocation of huge pages.
265
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266#
267# support for page migration
268#
269config MIGRATION
b20a3503 270 bool "Page migration"
6c5240ae 271 def_bool y
de32a817 272 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
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273 help
274 Allows the migration of the physical location of pages of processes
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275 while the virtual addresses are not changed. This is useful in
276 two situations. The first is on NUMA systems to put pages nearer
277 to the processors accessing. The second is when allocating huge
278 pages as migration can relocate pages to satisfy a huge page
279 allocation instead of reclaiming.
6550e07f 280
c177c81e 281config ARCH_ENABLE_HUGEPAGE_MIGRATION
6341e62b 282 bool
c177c81e 283
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284config PHYS_ADDR_T_64BIT
285 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
286
2a7326b5 287config BOUNCE
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288 bool "Enable bounce buffers"
289 default y
2a7326b5 290 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
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291 help
292 Enable bounce buffers for devices that cannot access
293 the full range of memory available to the CPU. Enabled
294 by default when ZONE_DMA or HIGHMEM is selected, but you
295 may say n to override this.
2a7326b5 296
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297# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
298# have more than 4GB of memory, but we don't currently use the IOTLB to present
299# a 32-bit address to OHCI. So we need to use a bounce pool instead.
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300config NEED_BOUNCE_POOL
301 bool
debeb297 302 default y if TILE && USB_OHCI_HCD
ffecfd1a 303
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304config NR_QUICK
305 int
306 depends on QUICKLIST
0176bd3d 307 default "2" if AVR32
6225e937 308 default "1"
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309
310config VIRT_TO_BUS
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311 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
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317
318config MMU_NOTIFIER
319 bool
83fe27ea 320 select SRCU
fc4d5c29 321
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322config KSM
323 bool "Enable KSM for page merging"
324 depends on MMU
325 help
326 Enable Kernel Samepage Merging: KSM periodically scans those areas
327 of an application's address space that an app has advised may be
328 mergeable. When it finds pages of identical content, it replaces
d0f209f6 329 the many instances by a single page with that content, so
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330 saving memory until one or another app needs to modify the content.
331 Recommended for use with KVM, or with other duplicative applications.
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332 See Documentation/vm/ksm.txt for more information: KSM is inactive
333 until a program has madvised that an area is MADV_MERGEABLE, and
334 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
f8af4da3 335
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336config DEFAULT_MMAP_MIN_ADDR
337 int "Low address space to protect from user allocation"
6e141546 338 depends on MMU
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339 default 4096
340 help
341 This is the portion of low virtual memory which should be protected
342 from userspace allocation. Keeping a user from writing to low pages
343 can help reduce the impact of kernel NULL pointer bugs.
344
345 For most ia64, ppc64 and x86 users with lots of address space
346 a value of 65536 is reasonable and should cause no problems.
347 On arm and other archs it should not be higher than 32768.
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348 Programs which use vm86 functionality or have some need to map
349 this low address space will need CAP_SYS_RAWIO or disable this
350 protection by setting the value to 0.
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351
352 This value can be changed after boot using the
353 /proc/sys/vm/mmap_min_addr tunable.
354
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355config ARCH_SUPPORTS_MEMORY_FAILURE
356 bool
e0a94c2a 357
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358config MEMORY_FAILURE
359 depends on MMU
d949f36f 360 depends on ARCH_SUPPORTS_MEMORY_FAILURE
6a46079c 361 bool "Enable recovery from hardware memory errors"
ee6f509c 362 select MEMORY_ISOLATION
97f0b134 363 select RAS
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364 help
365 Enables code to recover from some memory failures on systems
366 with MCA recovery. This allows a system to continue running
367 even when some of its memory has uncorrected errors. This requires
368 special hardware support and typically ECC memory.
369
cae681fc 370config HWPOISON_INJECT
413f9efb 371 tristate "HWPoison pages injector"
27df5068 372 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
478c5ffc 373 select PROC_PAGE_MONITOR
cae681fc 374
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375config NOMMU_INITIAL_TRIM_EXCESS
376 int "Turn on mmap() excess space trimming before booting"
377 depends on !MMU
378 default 1
379 help
380 The NOMMU mmap() frequently needs to allocate large contiguous chunks
381 of memory on which to store mappings, but it can only ask the system
382 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
383 more than it requires. To deal with this, mmap() is able to trim off
384 the excess and return it to the allocator.
385
386 If trimming is enabled, the excess is trimmed off and returned to the
387 system allocator, which can cause extra fragmentation, particularly
388 if there are a lot of transient processes.
389
390 If trimming is disabled, the excess is kept, but not used, which for
391 long-term mappings means that the space is wasted.
392
393 Trimming can be dynamically controlled through a sysctl option
394 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
395 excess pages there must be before trimming should occur, or zero if
396 no trimming is to occur.
397
398 This option specifies the initial value of this option. The default
399 of 1 says that all excess pages should be trimmed.
400
401 See Documentation/nommu-mmap.txt for more information.
bbddff05 402
4c76d9d1 403config TRANSPARENT_HUGEPAGE
13ece886 404 bool "Transparent Hugepage Support"
15626062 405 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
5d689240 406 select COMPACTION
57578c2e 407 select RADIX_TREE_MULTIORDER
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408 help
409 Transparent Hugepages allows the kernel to use huge pages and
410 huge tlb transparently to the applications whenever possible.
411 This feature can improve computing performance to certain
412 applications by speeding up page faults during memory
413 allocation, by reducing the number of tlb misses and by speeding
414 up the pagetable walking.
415
416 If memory constrained on embedded, you may want to say N.
417
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418choice
419 prompt "Transparent Hugepage Support sysfs defaults"
420 depends on TRANSPARENT_HUGEPAGE
421 default TRANSPARENT_HUGEPAGE_ALWAYS
422 help
423 Selects the sysfs defaults for Transparent Hugepage Support.
424
425 config TRANSPARENT_HUGEPAGE_ALWAYS
426 bool "always"
427 help
428 Enabling Transparent Hugepage always, can increase the
429 memory footprint of applications without a guaranteed
430 benefit but it will work automatically for all applications.
431
432 config TRANSPARENT_HUGEPAGE_MADVISE
433 bool "madvise"
434 help
435 Enabling Transparent Hugepage madvise, will only provide a
436 performance improvement benefit to the applications using
437 madvise(MADV_HUGEPAGE) but it won't risk to increase the
438 memory footprint of applications without a guaranteed
439 benefit.
440endchoice
441
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442#
443# UP and nommu archs use km based percpu allocator
444#
445config NEED_PER_CPU_KM
446 depends on !SMP
447 bool
448 default y
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449
450config CLEANCACHE
451 bool "Enable cleancache driver to cache clean pages if tmem is present"
452 default n
453 help
454 Cleancache can be thought of as a page-granularity victim cache
455 for clean pages that the kernel's pageframe replacement algorithm
456 (PFRA) would like to keep around, but can't since there isn't enough
457 memory. So when the PFRA "evicts" a page, it first attempts to use
140a1ef2 458 cleancache code to put the data contained in that page into
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459 "transcendent memory", memory that is not directly accessible or
460 addressable by the kernel and is of unknown and possibly
461 time-varying size. And when a cleancache-enabled
462 filesystem wishes to access a page in a file on disk, it first
463 checks cleancache to see if it already contains it; if it does,
464 the page is copied into the kernel and a disk access is avoided.
465 When a transcendent memory driver is available (such as zcache or
466 Xen transcendent memory), a significant I/O reduction
467 may be achieved. When none is available, all cleancache calls
468 are reduced to a single pointer-compare-against-NULL resulting
469 in a negligible performance hit.
470
471 If unsure, say Y to enable cleancache
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472
473config FRONTSWAP
474 bool "Enable frontswap to cache swap pages if tmem is present"
475 depends on SWAP
476 default n
477 help
478 Frontswap is so named because it can be thought of as the opposite
479 of a "backing" store for a swap device. The data is stored into
480 "transcendent memory", memory that is not directly accessible or
481 addressable by the kernel and is of unknown and possibly
482 time-varying size. When space in transcendent memory is available,
483 a significant swap I/O reduction may be achieved. When none is
484 available, all frontswap calls are reduced to a single pointer-
485 compare-against-NULL resulting in a negligible performance hit
486 and swap data is stored as normal on the matching swap device.
487
488 If unsure, say Y to enable frontswap.
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489
490config CMA
491 bool "Contiguous Memory Allocator"
de32a817 492 depends on HAVE_MEMBLOCK && MMU
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493 select MIGRATION
494 select MEMORY_ISOLATION
495 help
496 This enables the Contiguous Memory Allocator which allows other
497 subsystems to allocate big physically-contiguous blocks of memory.
498 CMA reserves a region of memory and allows only movable pages to
499 be allocated from it. This way, the kernel can use the memory for
500 pagecache and when a subsystem requests for contiguous area, the
501 allocated pages are migrated away to serve the contiguous request.
502
503 If unsure, say "n".
504
505config CMA_DEBUG
506 bool "CMA debug messages (DEVELOPMENT)"
507 depends on DEBUG_KERNEL && CMA
508 help
509 Turns on debug messages in CMA. This produces KERN_DEBUG
510 messages for every CMA call as well as various messages while
511 processing calls such as dma_alloc_from_contiguous().
512 This option does not affect warning and error messages.
bf550fc9 513
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514config CMA_DEBUGFS
515 bool "CMA debugfs interface"
516 depends on CMA && DEBUG_FS
517 help
518 Turns on the DebugFS interface for CMA.
519
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520config CMA_AREAS
521 int "Maximum count of the CMA areas"
522 depends on CMA
523 default 7
524 help
525 CMA allows to create CMA areas for particular purpose, mainly,
526 used as device private area. This parameter sets the maximum
527 number of CMA area in the system.
528
529 If unsure, leave the default value "7".
530
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531config MEM_SOFT_DIRTY
532 bool "Track memory changes"
533 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
534 select PROC_PAGE_MONITOR
4e2e2770 535 help
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536 This option enables memory changes tracking by introducing a
537 soft-dirty bit on pte-s. This bit it set when someone writes
538 into a page just as regular dirty bit, but unlike the latter
539 it can be cleared by hands.
540
541 See Documentation/vm/soft-dirty.txt for more details.
4e2e2770 542
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543config ZSWAP
544 bool "Compressed cache for swap pages (EXPERIMENTAL)"
545 depends on FRONTSWAP && CRYPTO=y
546 select CRYPTO_LZO
12d79d64 547 select ZPOOL
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548 default n
549 help
550 A lightweight compressed cache for swap pages. It takes
551 pages that are in the process of being swapped out and attempts to
552 compress them into a dynamically allocated RAM-based memory pool.
553 This can result in a significant I/O reduction on swap device and,
554 in the case where decompressing from RAM is faster that swap device
555 reads, can also improve workload performance.
556
557 This is marked experimental because it is a new feature (as of
558 v3.11) that interacts heavily with memory reclaim. While these
559 interactions don't cause any known issues on simple memory setups,
560 they have not be fully explored on the large set of potential
561 configurations and workloads that exist.
562
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563config ZPOOL
564 tristate "Common API for compressed memory storage"
565 default n
0f8975ec 566 help
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567 Compressed memory storage API. This allows using either zbud or
568 zsmalloc.
0f8975ec 569
af8d417a 570config ZBUD
9a001fc1 571 tristate "Low (Up to 2x) density storage for compressed pages"
af8d417a
DS
572 default n
573 help
574 A special purpose allocator for storing compressed pages.
575 It is designed to store up to two compressed pages per physical
576 page. While this design limits storage density, it has simple and
577 deterministic reclaim properties that make it preferable to a higher
578 density approach when reclaim will be used.
bcf1647d 579
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580config Z3FOLD
581 tristate "Up to 3x density storage for compressed pages"
582 depends on ZPOOL
583 default n
584 help
585 A special purpose allocator for storing compressed pages.
586 It is designed to store up to three compressed pages per physical
587 page. It is a ZBUD derivative so the simplicity and determinism are
588 still there.
589
bcf1647d 590config ZSMALLOC
d867f203 591 tristate "Memory allocator for compressed pages"
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592 depends on MMU
593 default n
594 help
595 zsmalloc is a slab-based memory allocator designed to store
596 compressed RAM pages. zsmalloc uses virtual memory mapping
597 in order to reduce fragmentation. However, this results in a
598 non-standard allocator interface where a handle, not a pointer, is
599 returned by an alloc(). This handle must be mapped in order to
600 access the allocated space.
601
602config PGTABLE_MAPPING
603 bool "Use page table mapping to access object in zsmalloc"
604 depends on ZSMALLOC
605 help
606 By default, zsmalloc uses a copy-based object mapping method to
607 access allocations that span two pages. However, if a particular
608 architecture (ex, ARM) performs VM mapping faster than copying,
609 then you should select this. This causes zsmalloc to use page table
610 mapping rather than copying for object mapping.
611
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612 You can check speed with zsmalloc benchmark:
613 https://github.com/spartacus06/zsmapbench
9e5c33d7 614
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615config ZSMALLOC_STAT
616 bool "Export zsmalloc statistics"
617 depends on ZSMALLOC
618 select DEBUG_FS
619 help
620 This option enables code in the zsmalloc to collect various
621 statistics about whats happening in zsmalloc and exports that
622 information to userspace via debugfs.
623 If unsure, say N.
624
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625config GENERIC_EARLY_IOREMAP
626 bool
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627
628config MAX_STACK_SIZE_MB
629 int "Maximum user stack size for 32-bit processes (MB)"
630 default 80
631 range 8 256 if METAG
632 range 8 2048
633 depends on STACK_GROWSUP && (!64BIT || COMPAT)
634 help
635 This is the maximum stack size in Megabytes in the VM layout of 32-bit
636 user processes when the stack grows upwards (currently only on parisc
637 and metag arch). The stack will be located at the highest memory
638 address minus the given value, unless the RLIMIT_STACK hard limit is
639 changed to a smaller value in which case that is used.
640
641 A sane initial value is 80 MB.
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642
643# For architectures that support deferred memory initialisation
644config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
645 bool
646
647config DEFERRED_STRUCT_PAGE_INIT
1ce22103 648 bool "Defer initialisation of struct pages to kthreads"
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649 default n
650 depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
11e68567 651 depends on NO_BOOTMEM && MEMORY_HOTPLUG
95794924 652 depends on !FLATMEM
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653 help
654 Ordinarily all struct pages are initialised during early boot in a
655 single thread. On very large machines this can take a considerable
656 amount of time. If this option is set, large machines will bring up
657 a subset of memmap at boot and then initialise the rest in parallel
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658 by starting one-off "pgdatinitX" kernel thread for each node X. This
659 has a potential performance impact on processes running early in the
660 lifetime of the system until these kthreads finish the
661 initialisation.
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663config IDLE_PAGE_TRACKING
664 bool "Enable idle page tracking"
665 depends on SYSFS && MMU
666 select PAGE_EXTENSION if !64BIT
667 help
668 This feature allows to estimate the amount of user pages that have
669 not been touched during a given period of time. This information can
670 be useful to tune memory cgroup limits and/or for job placement
671 within a compute cluster.
672
673 See Documentation/vm/idle_page_tracking.txt for more details.
674
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675config ZONE_DEVICE
676 bool "Device memory (pmem, etc...) hotplug support" if EXPERT
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677 depends on MEMORY_HOTPLUG
678 depends on MEMORY_HOTREMOVE
99490f16 679 depends on SPARSEMEM_VMEMMAP
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680 depends on X86_64 #arch_add_memory() comprehends device memory
681
682 help
683 Device memory hotplug support allows for establishing pmem,
684 or other device driver discovered memory regions, in the
685 memmap. This allows pfn_to_page() lookups of otherwise
686 "device-physical" addresses which is needed for using a DAX
687 mapping in an O_DIRECT operation, among other things.
688
689 If FS_DAX is enabled, then say Y.
06a660ad 690
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691config FRAME_VECTOR
692 bool
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693
694config ARCH_USES_HIGH_VMA_FLAGS
695 bool
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696config ARCH_HAS_PKEYS
697 bool