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1
2menu "Memory Management options"
3
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4config SELECT_MEMORY_MODEL
5 def_bool y
a8826eeb 6 depends on ARCH_SELECT_MEMORY_MODEL
e1785e85 7
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8choice
9 prompt "Memory model"
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10 depends on SELECT_MEMORY_MODEL
11 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
d41dee36 12 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
e1785e85 13 default FLATMEM_MANUAL
3a9da765 14
e1785e85 15config FLATMEM_MANUAL
3a9da765 16 bool "Flat Memory"
c898ec16 17 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
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18 help
19 This option allows you to change some of the ways that
20 Linux manages its memory internally. Most users will
21 only have one option here: FLATMEM. This is normal
22 and a correct option.
23
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24 Some users of more advanced features like NUMA and
25 memory hotplug may have different options here.
18f65332 26 DISCONTIGMEM is a more mature, better tested system,
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27 but is incompatible with memory hotplug and may suffer
28 decreased performance over SPARSEMEM. If unsure between
29 "Sparse Memory" and "Discontiguous Memory", choose
30 "Discontiguous Memory".
31
32 If unsure, choose this option (Flat Memory) over any other.
3a9da765 33
e1785e85 34config DISCONTIGMEM_MANUAL
f3519f91 35 bool "Discontiguous Memory"
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36 depends on ARCH_DISCONTIGMEM_ENABLE
37 help
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38 This option provides enhanced support for discontiguous
39 memory systems, over FLATMEM. These systems have holes
40 in their physical address spaces, and this option provides
41 more efficient handling of these holes. However, the vast
42 majority of hardware has quite flat address spaces, and
ad3d0a38 43 can have degraded performance from the extra overhead that
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44 this option imposes.
45
46 Many NUMA configurations will have this as the only option.
47
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48 If unsure, choose "Flat Memory" over this option.
49
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50config SPARSEMEM_MANUAL
51 bool "Sparse Memory"
52 depends on ARCH_SPARSEMEM_ENABLE
53 help
54 This will be the only option for some systems, including
55 memory hotplug systems. This is normal.
56
57 For many other systems, this will be an alternative to
f3519f91 58 "Discontiguous Memory". This option provides some potential
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59 performance benefits, along with decreased code complexity,
60 but it is newer, and more experimental.
61
62 If unsure, choose "Discontiguous Memory" or "Flat Memory"
63 over this option.
64
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65endchoice
66
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67config DISCONTIGMEM
68 def_bool y
69 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
70
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71config SPARSEMEM
72 def_bool y
1a83e175 73 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
d41dee36 74
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75config FLATMEM
76 def_bool y
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77 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
78
79config FLAT_NODE_MEM_MAP
80 def_bool y
81 depends on !SPARSEMEM
e1785e85 82
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83#
84# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
85# to represent different areas of memory. This variable allows
86# those dependencies to exist individually.
87#
88config NEED_MULTIPLE_NODES
89 def_bool y
90 depends on DISCONTIGMEM || NUMA
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91
92config HAVE_MEMORY_PRESENT
93 def_bool y
d41dee36 94 depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
802f192e 95
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96#
97# SPARSEMEM_EXTREME (which is the default) does some bootmem
84eb8d06 98# allocations when memory_present() is called. If this cannot
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99# be done on your architecture, select this option. However,
100# statically allocating the mem_section[] array can potentially
101# consume vast quantities of .bss, so be careful.
102#
103# This option will also potentially produce smaller runtime code
104# with gcc 3.4 and later.
105#
106config SPARSEMEM_STATIC
9ba16087 107 bool
3e347261 108
802f192e 109#
44c09201 110# Architecture platforms which require a two level mem_section in SPARSEMEM
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111# must select this option. This is usually for architecture platforms with
112# an extremely sparse physical address space.
113#
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114config SPARSEMEM_EXTREME
115 def_bool y
116 depends on SPARSEMEM && !SPARSEMEM_STATIC
4c21e2f2 117
29c71111 118config SPARSEMEM_VMEMMAP_ENABLE
9ba16087 119 bool
29c71111 120
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121config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
122 def_bool y
123 depends on SPARSEMEM && X86_64
124
29c71111 125config SPARSEMEM_VMEMMAP
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126 bool "Sparse Memory virtual memmap"
127 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
128 default y
129 help
130 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
131 pfn_to_page and page_to_pfn operations. This is the most
132 efficient option when sufficient kernel resources are available.
29c71111 133
95f72d1e 134config HAVE_MEMBLOCK
6341e62b 135 bool
95f72d1e 136
7c0caeb8 137config HAVE_MEMBLOCK_NODE_MAP
6341e62b 138 bool
7c0caeb8 139
70210ed9 140config HAVE_MEMBLOCK_PHYS_MAP
6341e62b 141 bool
70210ed9 142
e585513b 143config HAVE_GENERIC_GUP
6341e62b 144 bool
2667f50e 145
c378ddd5 146config ARCH_DISCARD_MEMBLOCK
6341e62b 147 bool
c378ddd5 148
66616720 149config NO_BOOTMEM
6341e62b 150 bool
66616720 151
ee6f509c 152config MEMORY_ISOLATION
6341e62b 153 bool
ee6f509c 154
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155#
156# Only be set on architectures that have completely implemented memory hotplug
157# feature. If you are not sure, don't touch it.
158#
159config HAVE_BOOTMEM_INFO_NODE
160 def_bool n
161
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162# eventually, we can have this option just 'select SPARSEMEM'
163config MEMORY_HOTPLUG
164 bool "Allow for memory hot-add"
ec69acbb 165 depends on SPARSEMEM || X86_64_ACPI_NUMA
40b31360 166 depends on ARCH_ENABLE_MEMORY_HOTPLUG
3947be19 167
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168config MEMORY_HOTPLUG_SPARSE
169 def_bool y
170 depends on SPARSEMEM && MEMORY_HOTPLUG
171
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172config MEMORY_HOTPLUG_DEFAULT_ONLINE
173 bool "Online the newly added memory blocks by default"
174 default n
175 depends on MEMORY_HOTPLUG
176 help
177 This option sets the default policy setting for memory hotplug
178 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
179 determines what happens to newly added memory regions. Policy setting
180 can always be changed at runtime.
181 See Documentation/memory-hotplug.txt for more information.
182
183 Say Y here if you want all hot-plugged memory blocks to appear in
184 'online' state by default.
185 Say N here if you want the default policy to keep all hot-plugged
186 memory blocks in 'offline' state.
187
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188config MEMORY_HOTREMOVE
189 bool "Allow for memory hot remove"
46723bfa 190 select MEMORY_ISOLATION
f7e3334a 191 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
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192 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
193 depends on MIGRATION
194
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195# Heavily threaded applications may benefit from splitting the mm-wide
196# page_table_lock, so that faults on different parts of the user address
197# space can be handled with less contention: split it at this NR_CPUS.
198# Default to 4 for wider testing, though 8 might be more appropriate.
199# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
7b6ac9df 200# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
a70caa8b 201# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
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202#
203config SPLIT_PTLOCK_CPUS
204 int
9164550e 205 default "999999" if !MMU
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206 default "999999" if ARM && !CPU_CACHE_VIPT
207 default "999999" if PARISC && !PA20
4c21e2f2 208 default "4"
7cbe34cf 209
e009bb30 210config ARCH_ENABLE_SPLIT_PMD_PTLOCK
6341e62b 211 bool
e009bb30 212
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213#
214# support for memory balloon
215config MEMORY_BALLOON
6341e62b 216 bool
09316c09 217
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218#
219# support for memory balloon compaction
220config BALLOON_COMPACTION
221 bool "Allow for balloon memory compaction/migration"
222 def_bool y
09316c09 223 depends on COMPACTION && MEMORY_BALLOON
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224 help
225 Memory fragmentation introduced by ballooning might reduce
226 significantly the number of 2MB contiguous memory blocks that can be
227 used within a guest, thus imposing performance penalties associated
228 with the reduced number of transparent huge pages that could be used
229 by the guest workload. Allowing the compaction & migration for memory
230 pages enlisted as being part of memory balloon devices avoids the
231 scenario aforementioned and helps improving memory defragmentation.
232
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233#
234# support for memory compaction
235config COMPACTION
236 bool "Allow for memory compaction"
05106e6a 237 def_bool y
e9e96b39 238 select MIGRATION
33a93877 239 depends on MMU
e9e96b39 240 help
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241 Compaction is the only memory management component to form
242 high order (larger physically contiguous) memory blocks
243 reliably. The page allocator relies on compaction heavily and
244 the lack of the feature can lead to unexpected OOM killer
245 invocations for high order memory requests. You shouldn't
246 disable this option unless there really is a strong reason for
247 it and then we would be really interested to hear about that at
248 linux-mm@kvack.org.
e9e96b39 249
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250#
251# support for page migration
252#
253config MIGRATION
b20a3503 254 bool "Page migration"
6c5240ae 255 def_bool y
de32a817 256 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
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257 help
258 Allows the migration of the physical location of pages of processes
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259 while the virtual addresses are not changed. This is useful in
260 two situations. The first is on NUMA systems to put pages nearer
261 to the processors accessing. The second is when allocating huge
262 pages as migration can relocate pages to satisfy a huge page
263 allocation instead of reclaiming.
6550e07f 264
c177c81e 265config ARCH_ENABLE_HUGEPAGE_MIGRATION
6341e62b 266 bool
c177c81e 267
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268config ARCH_ENABLE_THP_MIGRATION
269 bool
270
600715dc 271config PHYS_ADDR_T_64BIT
d4a451d5 272 def_bool 64BIT
600715dc 273
2a7326b5 274config BOUNCE
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275 bool "Enable bounce buffers"
276 default y
2a7326b5 277 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
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278 help
279 Enable bounce buffers for devices that cannot access
280 the full range of memory available to the CPU. Enabled
281 by default when ZONE_DMA or HIGHMEM is selected, but you
282 may say n to override this.
2a7326b5 283
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284config NR_QUICK
285 int
286 depends on QUICKLIST
287 default "1"
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288
289config VIRT_TO_BUS
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290 bool
291 help
292 An architecture should select this if it implements the
293 deprecated interface virt_to_bus(). All new architectures
294 should probably not select this.
295
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296
297config MMU_NOTIFIER
298 bool
83fe27ea 299 select SRCU
fc4d5c29 300
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301config KSM
302 bool "Enable KSM for page merging"
303 depends on MMU
304 help
305 Enable Kernel Samepage Merging: KSM periodically scans those areas
306 of an application's address space that an app has advised may be
307 mergeable. When it finds pages of identical content, it replaces
d0f209f6 308 the many instances by a single page with that content, so
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309 saving memory until one or another app needs to modify the content.
310 Recommended for use with KVM, or with other duplicative applications.
ad56b738 311 See Documentation/vm/ksm.rst for more information: KSM is inactive
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312 until a program has madvised that an area is MADV_MERGEABLE, and
313 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
f8af4da3 314
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315config DEFAULT_MMAP_MIN_ADDR
316 int "Low address space to protect from user allocation"
6e141546 317 depends on MMU
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318 default 4096
319 help
320 This is the portion of low virtual memory which should be protected
321 from userspace allocation. Keeping a user from writing to low pages
322 can help reduce the impact of kernel NULL pointer bugs.
323
324 For most ia64, ppc64 and x86 users with lots of address space
325 a value of 65536 is reasonable and should cause no problems.
326 On arm and other archs it should not be higher than 32768.
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327 Programs which use vm86 functionality or have some need to map
328 this low address space will need CAP_SYS_RAWIO or disable this
329 protection by setting the value to 0.
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330
331 This value can be changed after boot using the
332 /proc/sys/vm/mmap_min_addr tunable.
333
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334config ARCH_SUPPORTS_MEMORY_FAILURE
335 bool
e0a94c2a 336
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337config MEMORY_FAILURE
338 depends on MMU
d949f36f 339 depends on ARCH_SUPPORTS_MEMORY_FAILURE
6a46079c 340 bool "Enable recovery from hardware memory errors"
ee6f509c 341 select MEMORY_ISOLATION
97f0b134 342 select RAS
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343 help
344 Enables code to recover from some memory failures on systems
345 with MCA recovery. This allows a system to continue running
346 even when some of its memory has uncorrected errors. This requires
347 special hardware support and typically ECC memory.
348
cae681fc 349config HWPOISON_INJECT
413f9efb 350 tristate "HWPoison pages injector"
27df5068 351 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
478c5ffc 352 select PROC_PAGE_MONITOR
cae681fc 353
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354config NOMMU_INITIAL_TRIM_EXCESS
355 int "Turn on mmap() excess space trimming before booting"
356 depends on !MMU
357 default 1
358 help
359 The NOMMU mmap() frequently needs to allocate large contiguous chunks
360 of memory on which to store mappings, but it can only ask the system
361 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
362 more than it requires. To deal with this, mmap() is able to trim off
363 the excess and return it to the allocator.
364
365 If trimming is enabled, the excess is trimmed off and returned to the
366 system allocator, which can cause extra fragmentation, particularly
367 if there are a lot of transient processes.
368
369 If trimming is disabled, the excess is kept, but not used, which for
370 long-term mappings means that the space is wasted.
371
372 Trimming can be dynamically controlled through a sysctl option
373 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
374 excess pages there must be before trimming should occur, or zero if
375 no trimming is to occur.
376
377 This option specifies the initial value of this option. The default
378 of 1 says that all excess pages should be trimmed.
379
380 See Documentation/nommu-mmap.txt for more information.
bbddff05 381
4c76d9d1 382config TRANSPARENT_HUGEPAGE
13ece886 383 bool "Transparent Hugepage Support"
15626062 384 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
5d689240 385 select COMPACTION
57578c2e 386 select RADIX_TREE_MULTIORDER
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387 help
388 Transparent Hugepages allows the kernel to use huge pages and
389 huge tlb transparently to the applications whenever possible.
390 This feature can improve computing performance to certain
391 applications by speeding up page faults during memory
392 allocation, by reducing the number of tlb misses and by speeding
393 up the pagetable walking.
394
395 If memory constrained on embedded, you may want to say N.
396
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397choice
398 prompt "Transparent Hugepage Support sysfs defaults"
399 depends on TRANSPARENT_HUGEPAGE
400 default TRANSPARENT_HUGEPAGE_ALWAYS
401 help
402 Selects the sysfs defaults for Transparent Hugepage Support.
403
404 config TRANSPARENT_HUGEPAGE_ALWAYS
405 bool "always"
406 help
407 Enabling Transparent Hugepage always, can increase the
408 memory footprint of applications without a guaranteed
409 benefit but it will work automatically for all applications.
410
411 config TRANSPARENT_HUGEPAGE_MADVISE
412 bool "madvise"
413 help
414 Enabling Transparent Hugepage madvise, will only provide a
415 performance improvement benefit to the applications using
416 madvise(MADV_HUGEPAGE) but it won't risk to increase the
417 memory footprint of applications without a guaranteed
418 benefit.
419endchoice
420
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421config ARCH_WANTS_THP_SWAP
422 def_bool n
423
424config THP_SWAP
425 def_bool y
426 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP
427 help
428 Swap transparent huge pages in one piece, without splitting.
429 XXX: For now this only does clustered swap space allocation.
430
431 For selection by architectures with reasonable THP sizes.
432
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433config TRANSPARENT_HUGE_PAGECACHE
434 def_bool y
953c66c2 435 depends on TRANSPARENT_HUGEPAGE
e496cf3d 436
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437#
438# UP and nommu archs use km based percpu allocator
439#
440config NEED_PER_CPU_KM
441 depends on !SMP
442 bool
443 default y
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444
445config CLEANCACHE
446 bool "Enable cleancache driver to cache clean pages if tmem is present"
447 default n
448 help
449 Cleancache can be thought of as a page-granularity victim cache
450 for clean pages that the kernel's pageframe replacement algorithm
451 (PFRA) would like to keep around, but can't since there isn't enough
452 memory. So when the PFRA "evicts" a page, it first attempts to use
140a1ef2 453 cleancache code to put the data contained in that page into
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454 "transcendent memory", memory that is not directly accessible or
455 addressable by the kernel and is of unknown and possibly
456 time-varying size. And when a cleancache-enabled
457 filesystem wishes to access a page in a file on disk, it first
458 checks cleancache to see if it already contains it; if it does,
459 the page is copied into the kernel and a disk access is avoided.
460 When a transcendent memory driver is available (such as zcache or
461 Xen transcendent memory), a significant I/O reduction
462 may be achieved. When none is available, all cleancache calls
463 are reduced to a single pointer-compare-against-NULL resulting
464 in a negligible performance hit.
465
466 If unsure, say Y to enable cleancache
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467
468config FRONTSWAP
469 bool "Enable frontswap to cache swap pages if tmem is present"
470 depends on SWAP
471 default n
472 help
473 Frontswap is so named because it can be thought of as the opposite
474 of a "backing" store for a swap device. The data is stored into
475 "transcendent memory", memory that is not directly accessible or
476 addressable by the kernel and is of unknown and possibly
477 time-varying size. When space in transcendent memory is available,
478 a significant swap I/O reduction may be achieved. When none is
479 available, all frontswap calls are reduced to a single pointer-
480 compare-against-NULL resulting in a negligible performance hit
481 and swap data is stored as normal on the matching swap device.
482
483 If unsure, say Y to enable frontswap.
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484
485config CMA
486 bool "Contiguous Memory Allocator"
de32a817 487 depends on HAVE_MEMBLOCK && MMU
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488 select MIGRATION
489 select MEMORY_ISOLATION
490 help
491 This enables the Contiguous Memory Allocator which allows other
492 subsystems to allocate big physically-contiguous blocks of memory.
493 CMA reserves a region of memory and allows only movable pages to
494 be allocated from it. This way, the kernel can use the memory for
495 pagecache and when a subsystem requests for contiguous area, the
496 allocated pages are migrated away to serve the contiguous request.
497
498 If unsure, say "n".
499
500config CMA_DEBUG
501 bool "CMA debug messages (DEVELOPMENT)"
502 depends on DEBUG_KERNEL && CMA
503 help
504 Turns on debug messages in CMA. This produces KERN_DEBUG
505 messages for every CMA call as well as various messages while
506 processing calls such as dma_alloc_from_contiguous().
507 This option does not affect warning and error messages.
bf550fc9 508
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509config CMA_DEBUGFS
510 bool "CMA debugfs interface"
511 depends on CMA && DEBUG_FS
512 help
513 Turns on the DebugFS interface for CMA.
514
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515config CMA_AREAS
516 int "Maximum count of the CMA areas"
517 depends on CMA
518 default 7
519 help
520 CMA allows to create CMA areas for particular purpose, mainly,
521 used as device private area. This parameter sets the maximum
522 number of CMA area in the system.
523
524 If unsure, leave the default value "7".
525
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526config MEM_SOFT_DIRTY
527 bool "Track memory changes"
528 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
529 select PROC_PAGE_MONITOR
4e2e2770 530 help
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531 This option enables memory changes tracking by introducing a
532 soft-dirty bit on pte-s. This bit it set when someone writes
533 into a page just as regular dirty bit, but unlike the latter
534 it can be cleared by hands.
535
1ad1335d 536 See Documentation/admin-guide/mm/soft-dirty.rst for more details.
4e2e2770 537
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538config ZSWAP
539 bool "Compressed cache for swap pages (EXPERIMENTAL)"
540 depends on FRONTSWAP && CRYPTO=y
541 select CRYPTO_LZO
12d79d64 542 select ZPOOL
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543 default n
544 help
545 A lightweight compressed cache for swap pages. It takes
546 pages that are in the process of being swapped out and attempts to
547 compress them into a dynamically allocated RAM-based memory pool.
548 This can result in a significant I/O reduction on swap device and,
549 in the case where decompressing from RAM is faster that swap device
550 reads, can also improve workload performance.
551
552 This is marked experimental because it is a new feature (as of
553 v3.11) that interacts heavily with memory reclaim. While these
554 interactions don't cause any known issues on simple memory setups,
555 they have not be fully explored on the large set of potential
556 configurations and workloads that exist.
557
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558config ZPOOL
559 tristate "Common API for compressed memory storage"
560 default n
0f8975ec 561 help
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562 Compressed memory storage API. This allows using either zbud or
563 zsmalloc.
0f8975ec 564
af8d417a 565config ZBUD
9a001fc1 566 tristate "Low (Up to 2x) density storage for compressed pages"
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567 default n
568 help
569 A special purpose allocator for storing compressed pages.
570 It is designed to store up to two compressed pages per physical
571 page. While this design limits storage density, it has simple and
572 deterministic reclaim properties that make it preferable to a higher
573 density approach when reclaim will be used.
bcf1647d 574
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575config Z3FOLD
576 tristate "Up to 3x density storage for compressed pages"
577 depends on ZPOOL
578 default n
579 help
580 A special purpose allocator for storing compressed pages.
581 It is designed to store up to three compressed pages per physical
582 page. It is a ZBUD derivative so the simplicity and determinism are
583 still there.
584
bcf1647d 585config ZSMALLOC
d867f203 586 tristate "Memory allocator for compressed pages"
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587 depends on MMU
588 default n
589 help
590 zsmalloc is a slab-based memory allocator designed to store
591 compressed RAM pages. zsmalloc uses virtual memory mapping
592 in order to reduce fragmentation. However, this results in a
593 non-standard allocator interface where a handle, not a pointer, is
594 returned by an alloc(). This handle must be mapped in order to
595 access the allocated space.
596
597config PGTABLE_MAPPING
598 bool "Use page table mapping to access object in zsmalloc"
599 depends on ZSMALLOC
600 help
601 By default, zsmalloc uses a copy-based object mapping method to
602 access allocations that span two pages. However, if a particular
603 architecture (ex, ARM) performs VM mapping faster than copying,
604 then you should select this. This causes zsmalloc to use page table
605 mapping rather than copying for object mapping.
606
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607 You can check speed with zsmalloc benchmark:
608 https://github.com/spartacus06/zsmapbench
9e5c33d7 609
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610config ZSMALLOC_STAT
611 bool "Export zsmalloc statistics"
612 depends on ZSMALLOC
613 select DEBUG_FS
614 help
615 This option enables code in the zsmalloc to collect various
616 statistics about whats happening in zsmalloc and exports that
617 information to userspace via debugfs.
618 If unsure, say N.
619
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620config GENERIC_EARLY_IOREMAP
621 bool
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622
623config MAX_STACK_SIZE_MB
624 int "Maximum user stack size for 32-bit processes (MB)"
625 default 80
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626 range 8 2048
627 depends on STACK_GROWSUP && (!64BIT || COMPAT)
628 help
629 This is the maximum stack size in Megabytes in the VM layout of 32-bit
630 user processes when the stack grows upwards (currently only on parisc
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631 arch). The stack will be located at the highest memory address minus
632 the given value, unless the RLIMIT_STACK hard limit is changed to a
633 smaller value in which case that is used.
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634
635 A sane initial value is 80 MB.
3a80a7fa 636
3a80a7fa 637config DEFERRED_STRUCT_PAGE_INIT
1ce22103 638 bool "Defer initialisation of struct pages to kthreads"
3a80a7fa 639 default n
2e3ca40f 640 depends on NO_BOOTMEM
95794924 641 depends on !FLATMEM
ab1e8d89 642 depends on !NEED_PER_CPU_KM
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643 help
644 Ordinarily all struct pages are initialised during early boot in a
645 single thread. On very large machines this can take a considerable
646 amount of time. If this option is set, large machines will bring up
647 a subset of memmap at boot and then initialise the rest in parallel
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648 by starting one-off "pgdatinitX" kernel thread for each node X. This
649 has a potential performance impact on processes running early in the
650 lifetime of the system until these kthreads finish the
651 initialisation.
033fbae9 652
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653config IDLE_PAGE_TRACKING
654 bool "Enable idle page tracking"
655 depends on SYSFS && MMU
656 select PAGE_EXTENSION if !64BIT
657 help
658 This feature allows to estimate the amount of user pages that have
659 not been touched during a given period of time. This information can
660 be useful to tune memory cgroup limits and/or for job placement
661 within a compute cluster.
662
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663 See Documentation/admin-guide/mm/idle_page_tracking.rst for
664 more details.
33c3fc71 665
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666# arch_add_memory() comprehends device memory
667config ARCH_HAS_ZONE_DEVICE
668 bool
669
033fbae9 670config ZONE_DEVICE
5042db43 671 bool "Device memory (pmem, HMM, etc...) hotplug support"
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672 depends on MEMORY_HOTPLUG
673 depends on MEMORY_HOTREMOVE
99490f16 674 depends on SPARSEMEM_VMEMMAP
65f7d049 675 depends on ARCH_HAS_ZONE_DEVICE
ab1b597e 676 select RADIX_TREE_MULTIORDER
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677
678 help
679 Device memory hotplug support allows for establishing pmem,
680 or other device driver discovered memory regions, in the
681 memmap. This allows pfn_to_page() lookups of otherwise
682 "device-physical" addresses which is needed for using a DAX
683 mapping in an O_DIRECT operation, among other things.
684
685 If FS_DAX is enabled, then say Y.
06a660ad 686
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687config ARCH_HAS_HMM
688 bool
689 default y
690 depends on (X86_64 || PPC64)
691 depends on ZONE_DEVICE
692 depends on MMU && 64BIT
693 depends on MEMORY_HOTPLUG
694 depends on MEMORY_HOTREMOVE
695 depends on SPARSEMEM_VMEMMAP
696
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697config MIGRATE_VMA_HELPER
698 bool
699
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700config DEV_PAGEMAP_OPS
701 bool
702
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703config HMM
704 bool
6b368cd4 705 select MIGRATE_VMA_HELPER
133ff0ea 706
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707config HMM_MIRROR
708 bool "HMM mirror CPU page table into a device page table"
709 depends on ARCH_HAS_HMM
710 select MMU_NOTIFIER
711 select HMM
712 help
713 Select HMM_MIRROR if you want to mirror range of the CPU page table of a
714 process into a device page table. Here, mirror means "keep synchronized".
715 Prerequisites: the device must provide the ability to write-protect its
716 page tables (at PAGE_SIZE granularity), and must be able to recover from
717 the resulting potential page faults.
718
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719config DEVICE_PRIVATE
720 bool "Unaddressable device memory (GPU memory, ...)"
721 depends on ARCH_HAS_HMM
df6ad698 722 select HMM
e7638488 723 select DEV_PAGEMAP_OPS
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724
725 help
726 Allows creation of struct pages to represent unaddressable device
727 memory; i.e., memory that is only accessible from the device (or
728 group of devices). You likely also want to select HMM_MIRROR.
729
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730config DEVICE_PUBLIC
731 bool "Addressable device memory (like GPU memory)"
732 depends on ARCH_HAS_HMM
733 select HMM
e7638488 734 select DEV_PAGEMAP_OPS
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735
736 help
737 Allows creation of struct pages to represent addressable device
738 memory; i.e., memory that is accessible from both the device and
739 the CPU
740
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741config FRAME_VECTOR
742 bool
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743
744config ARCH_USES_HIGH_VMA_FLAGS
745 bool
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746config ARCH_HAS_PKEYS
747 bool
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748
749config PERCPU_STATS
750 bool "Collect percpu memory statistics"
751 default n
752 help
753 This feature collects and exposes statistics via debugfs. The
754 information includes global and per chunk statistics, which can
755 be used to help understand percpu memory usage.
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756
757config GUP_BENCHMARK
758 bool "Enable infrastructure for get_user_pages_fast() benchmarking"
759 default n
760 help
761 Provides /sys/kernel/debug/gup_benchmark that helps with testing
762 performance of get_user_pages_fast().
763
764 See tools/testing/selftests/vm/gup_benchmark.c
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765
766config ARCH_HAS_PTE_SPECIAL
767 bool
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768
769endmenu