Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4

Linux/mm/Kconfig

  1 config SELECT_MEMORY_MODEL
  2         def_bool y
  3         depends on ARCH_SELECT_MEMORY_MODEL
  4 
  5 choice
  6         prompt "Memory model"
  7         depends on SELECT_MEMORY_MODEL
  8         default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
  9         default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 10         default FLATMEM_MANUAL
 11 
 12 config FLATMEM_MANUAL
 13         bool "Flat Memory"
 14         depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
 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 
 21           Some users of more advanced features like NUMA and
 22           memory hotplug may have different options here.
 23           DISCONTIGMEM is a more mature, better tested system,
 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.
 30 
 31 config DISCONTIGMEM_MANUAL
 32         bool "Discontiguous Memory"
 33         depends on ARCH_DISCONTIGMEM_ENABLE
 34         help
 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
 40           can have degraded performance from the extra overhead that
 41           this option imposes.
 42 
 43           Many NUMA configurations will have this as the only option.
 44 
 45           If unsure, choose "Flat Memory" over this option.
 46 
 47 config 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
 55           "Discontiguous Memory".  This option provides some potential
 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 
 62 endchoice
 63 
 64 config DISCONTIGMEM
 65         def_bool y
 66         depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
 67 
 68 config SPARSEMEM
 69         def_bool y
 70         depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 71 
 72 config FLATMEM
 73         def_bool y
 74         depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
 75 
 76 config FLAT_NODE_MEM_MAP
 77         def_bool y
 78         depends on !SPARSEMEM
 79 
 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 #
 85 config NEED_MULTIPLE_NODES
 86         def_bool y
 87         depends on DISCONTIGMEM || NUMA
 88 
 89 config HAVE_MEMORY_PRESENT
 90         def_bool y
 91         depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
 92 
 93 #
 94 # SPARSEMEM_EXTREME (which is the default) does some bootmem
 95 # allocations when memory_present() is called.  If this cannot
 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 #
103 config SPARSEMEM_STATIC
104         bool
105 
106 #
107 # Architecture platforms which require a two level mem_section in SPARSEMEM
108 # must select this option. This is usually for architecture platforms with
109 # an extremely sparse physical address space.
110 #
111 config SPARSEMEM_EXTREME
112         def_bool y
113         depends on SPARSEMEM && !SPARSEMEM_STATIC
114 
115 config SPARSEMEM_VMEMMAP_ENABLE
116         bool
117 
118 config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119         def_bool y
120         depends on SPARSEMEM && X86_64
121 
122 config SPARSEMEM_VMEMMAP
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.
130 
131 config HAVE_MEMBLOCK
132         bool
133 
134 config HAVE_MEMBLOCK_NODE_MAP
135         bool
136 
137 config HAVE_MEMBLOCK_PHYS_MAP
138         bool
139 
140 config HAVE_GENERIC_RCU_GUP
141         bool
142 
143 config ARCH_DISCARD_MEMBLOCK
144         bool
145 
146 config NO_BOOTMEM
147         bool
148 
149 config MEMORY_ISOLATION
150         bool
151 
152 config MOVABLE_NODE
153         bool "Enable to assign a node which has only movable memory"
154         depends on HAVE_MEMBLOCK
155         depends on NO_BOOTMEM
156         depends on X86_64
157         depends on NUMA
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
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.
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.
177 
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 #
182 config HAVE_BOOTMEM_INFO_NODE
183         def_bool n
184 
185 # eventually, we can have this option just 'select SPARSEMEM'
186 config MEMORY_HOTPLUG
187         bool "Allow for memory hot-add"
188         depends on SPARSEMEM || X86_64_ACPI_NUMA
189         depends on ARCH_ENABLE_MEMORY_HOTPLUG
190         depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
191 
192 config MEMORY_HOTPLUG_SPARSE
193         def_bool y
194         depends on SPARSEMEM && MEMORY_HOTPLUG
195 
196 config MEMORY_HOTREMOVE
197         bool "Allow for memory hot remove"
198         select MEMORY_ISOLATION
199         select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
200         depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
201         depends on MIGRATION
202 
203 # Heavily threaded applications may benefit from splitting the mm-wide
204 # page_table_lock, so that faults on different parts of the user address
205 # space can be handled with less contention: split it at this NR_CPUS.
206 # Default to 4 for wider testing, though 8 might be more appropriate.
207 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
208 # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
209 # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
210 #
211 config SPLIT_PTLOCK_CPUS
212         int
213         default "999999" if !MMU
214         default "999999" if ARM && !CPU_CACHE_VIPT
215         default "999999" if PARISC && !PA20
216         default "4"
217 
218 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
219         bool
220 
221 #
222 # support for memory balloon
223 config MEMORY_BALLOON
224         bool
225 
226 #
227 # support for memory balloon compaction
228 config BALLOON_COMPACTION
229         bool "Allow for balloon memory compaction/migration"
230         def_bool y
231         depends on COMPACTION && MEMORY_BALLOON
232         help
233           Memory fragmentation introduced by ballooning might reduce
234           significantly the number of 2MB contiguous memory blocks that can be
235           used within a guest, thus imposing performance penalties associated
236           with the reduced number of transparent huge pages that could be used
237           by the guest workload. Allowing the compaction & migration for memory
238           pages enlisted as being part of memory balloon devices avoids the
239           scenario aforementioned and helps improving memory defragmentation.
240 
241 #
242 # support for memory compaction
243 config COMPACTION
244         bool "Allow for memory compaction"
245         def_bool y
246         select MIGRATION
247         depends on MMU
248         help
249           Allows the compaction of memory for the allocation of huge pages.
250 
251 #
252 # support for page migration
253 #
254 config MIGRATION
255         bool "Page migration"
256         def_bool y
257         depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
258         help
259           Allows the migration of the physical location of pages of processes
260           while the virtual addresses are not changed. This is useful in
261           two situations. The first is on NUMA systems to put pages nearer
262           to the processors accessing. The second is when allocating huge
263           pages as migration can relocate pages to satisfy a huge page
264           allocation instead of reclaiming.
265 
266 config ARCH_ENABLE_HUGEPAGE_MIGRATION
267         bool
268 
269 config PHYS_ADDR_T_64BIT
270         def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
271 
272 config ZONE_DMA_FLAG
273         int
274         default "0" if !ZONE_DMA
275         default "1"
276 
277 config BOUNCE
278         bool "Enable bounce buffers"
279         default y
280         depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
281         help
282           Enable bounce buffers for devices that cannot access
283           the full range of memory available to the CPU. Enabled
284           by default when ZONE_DMA or HIGHMEM is selected, but you
285           may say n to override this.
286 
287 # On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
288 # have more than 4GB of memory, but we don't currently use the IOTLB to present
289 # a 32-bit address to OHCI.  So we need to use a bounce pool instead.
290 config NEED_BOUNCE_POOL
291         bool
292         default y if TILE && USB_OHCI_HCD
293 
294 config NR_QUICK
295         int
296         depends on QUICKLIST
297         default "2" if AVR32
298         default "1"
299 
300 config VIRT_TO_BUS
301         bool
302         help
303           An architecture should select this if it implements the
304           deprecated interface virt_to_bus().  All new architectures
305           should probably not select this.
306 
307 
308 config MMU_NOTIFIER
309         bool
310         select SRCU
311 
312 config KSM
313         bool "Enable KSM for page merging"
314         depends on MMU
315         help
316           Enable Kernel Samepage Merging: KSM periodically scans those areas
317           of an application's address space that an app has advised may be
318           mergeable.  When it finds pages of identical content, it replaces
319           the many instances by a single page with that content, so
320           saving memory until one or another app needs to modify the content.
321           Recommended for use with KVM, or with other duplicative applications.
322           See Documentation/vm/ksm.txt for more information: KSM is inactive
323           until a program has madvised that an area is MADV_MERGEABLE, and
324           root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
325 
326 config DEFAULT_MMAP_MIN_ADDR
327         int "Low address space to protect from user allocation"
328         depends on MMU
329         default 4096
330         help
331           This is the portion of low virtual memory which should be protected
332           from userspace allocation.  Keeping a user from writing to low pages
333           can help reduce the impact of kernel NULL pointer bugs.
334 
335           For most ia64, ppc64 and x86 users with lots of address space
336           a value of 65536 is reasonable and should cause no problems.
337           On arm and other archs it should not be higher than 32768.
338           Programs which use vm86 functionality or have some need to map
339           this low address space will need CAP_SYS_RAWIO or disable this
340           protection by setting the value to 0.
341 
342           This value can be changed after boot using the
343           /proc/sys/vm/mmap_min_addr tunable.
344 
345 config ARCH_SUPPORTS_MEMORY_FAILURE
346         bool
347 
348 config MEMORY_FAILURE
349         depends on MMU
350         depends on ARCH_SUPPORTS_MEMORY_FAILURE
351         bool "Enable recovery from hardware memory errors"
352         select MEMORY_ISOLATION
353         select RAS
354         help
355           Enables code to recover from some memory failures on systems
356           with MCA recovery. This allows a system to continue running
357           even when some of its memory has uncorrected errors. This requires
358           special hardware support and typically ECC memory.
359 
360 config HWPOISON_INJECT
361         tristate "HWPoison pages injector"
362         depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
363         select PROC_PAGE_MONITOR
364 
365 config NOMMU_INITIAL_TRIM_EXCESS
366         int "Turn on mmap() excess space trimming before booting"
367         depends on !MMU
368         default 1
369         help
370           The NOMMU mmap() frequently needs to allocate large contiguous chunks
371           of memory on which to store mappings, but it can only ask the system
372           allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
373           more than it requires.  To deal with this, mmap() is able to trim off
374           the excess and return it to the allocator.
375 
376           If trimming is enabled, the excess is trimmed off and returned to the
377           system allocator, which can cause extra fragmentation, particularly
378           if there are a lot of transient processes.
379 
380           If trimming is disabled, the excess is kept, but not used, which for
381           long-term mappings means that the space is wasted.
382 
383           Trimming can be dynamically controlled through a sysctl option
384           (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
385           excess pages there must be before trimming should occur, or zero if
386           no trimming is to occur.
387 
388           This option specifies the initial value of this option.  The default
389           of 1 says that all excess pages should be trimmed.
390 
391           See Documentation/nommu-mmap.txt for more information.
392 
393 config TRANSPARENT_HUGEPAGE
394         bool "Transparent Hugepage Support"
395         depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
396         select COMPACTION
397         help
398           Transparent Hugepages allows the kernel to use huge pages and
399           huge tlb transparently to the applications whenever possible.
400           This feature can improve computing performance to certain
401           applications by speeding up page faults during memory
402           allocation, by reducing the number of tlb misses and by speeding
403           up the pagetable walking.
404 
405           If memory constrained on embedded, you may want to say N.
406 
407 choice
408         prompt "Transparent Hugepage Support sysfs defaults"
409         depends on TRANSPARENT_HUGEPAGE
410         default TRANSPARENT_HUGEPAGE_ALWAYS
411         help
412           Selects the sysfs defaults for Transparent Hugepage Support.
413 
414         config TRANSPARENT_HUGEPAGE_ALWAYS
415                 bool "always"
416         help
417           Enabling Transparent Hugepage always, can increase the
418           memory footprint of applications without a guaranteed
419           benefit but it will work automatically for all applications.
420 
421         config TRANSPARENT_HUGEPAGE_MADVISE
422                 bool "madvise"
423         help
424           Enabling Transparent Hugepage madvise, will only provide a
425           performance improvement benefit to the applications using
426           madvise(MADV_HUGEPAGE) but it won't risk to increase the
427           memory footprint of applications without a guaranteed
428           benefit.
429 endchoice
430 
431 #
432 # UP and nommu archs use km based percpu allocator
433 #
434 config NEED_PER_CPU_KM
435         depends on !SMP
436         bool
437         default y
438 
439 config CLEANCACHE
440         bool "Enable cleancache driver to cache clean pages if tmem is present"
441         default n
442         help
443           Cleancache can be thought of as a page-granularity victim cache
444           for clean pages that the kernel's pageframe replacement algorithm
445           (PFRA) would like to keep around, but can't since there isn't enough
446           memory.  So when the PFRA "evicts" a page, it first attempts to use
447           cleancache code to put the data contained in that page into
448           "transcendent memory", memory that is not directly accessible or
449           addressable by the kernel and is of unknown and possibly
450           time-varying size.  And when a cleancache-enabled
451           filesystem wishes to access a page in a file on disk, it first
452           checks cleancache to see if it already contains it; if it does,
453           the page is copied into the kernel and a disk access is avoided.
454           When a transcendent memory driver is available (such as zcache or
455           Xen transcendent memory), a significant I/O reduction
456           may be achieved.  When none is available, all cleancache calls
457           are reduced to a single pointer-compare-against-NULL resulting
458           in a negligible performance hit.
459 
460           If unsure, say Y to enable cleancache
461 
462 config FRONTSWAP
463         bool "Enable frontswap to cache swap pages if tmem is present"
464         depends on SWAP
465         default n
466         help
467           Frontswap is so named because it can be thought of as the opposite
468           of a "backing" store for a swap device.  The data is stored into
469           "transcendent memory", memory that is not directly accessible or
470           addressable by the kernel and is of unknown and possibly
471           time-varying size.  When space in transcendent memory is available,
472           a significant swap I/O reduction may be achieved.  When none is
473           available, all frontswap calls are reduced to a single pointer-
474           compare-against-NULL resulting in a negligible performance hit
475           and swap data is stored as normal on the matching swap device.
476 
477           If unsure, say Y to enable frontswap.
478 
479 config CMA
480         bool "Contiguous Memory Allocator"
481         depends on HAVE_MEMBLOCK && MMU
482         select MIGRATION
483         select MEMORY_ISOLATION
484         help
485           This enables the Contiguous Memory Allocator which allows other
486           subsystems to allocate big physically-contiguous blocks of memory.
487           CMA reserves a region of memory and allows only movable pages to
488           be allocated from it. This way, the kernel can use the memory for
489           pagecache and when a subsystem requests for contiguous area, the
490           allocated pages are migrated away to serve the contiguous request.
491 
492           If unsure, say "n".
493 
494 config CMA_DEBUG
495         bool "CMA debug messages (DEVELOPMENT)"
496         depends on DEBUG_KERNEL && CMA
497         help
498           Turns on debug messages in CMA.  This produces KERN_DEBUG
499           messages for every CMA call as well as various messages while
500           processing calls such as dma_alloc_from_contiguous().
501           This option does not affect warning and error messages.
502 
503 config CMA_DEBUGFS
504         bool "CMA debugfs interface"
505         depends on CMA && DEBUG_FS
506         help
507           Turns on the DebugFS interface for CMA.
508 
509 config CMA_AREAS
510         int "Maximum count of the CMA areas"
511         depends on CMA
512         default 7
513         help
514           CMA allows to create CMA areas for particular purpose, mainly,
515           used as device private area. This parameter sets the maximum
516           number of CMA area in the system.
517 
518           If unsure, leave the default value "7".
519 
520 config MEM_SOFT_DIRTY
521         bool "Track memory changes"
522         depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
523         select PROC_PAGE_MONITOR
524         help
525           This option enables memory changes tracking by introducing a
526           soft-dirty bit on pte-s. This bit it set when someone writes
527           into a page just as regular dirty bit, but unlike the latter
528           it can be cleared by hands.
529 
530           See Documentation/vm/soft-dirty.txt for more details.
531 
532 config ZSWAP
533         bool "Compressed cache for swap pages (EXPERIMENTAL)"
534         depends on FRONTSWAP && CRYPTO=y
535         select CRYPTO_LZO
536         select ZPOOL
537         default n
538         help
539           A lightweight compressed cache for swap pages.  It takes
540           pages that are in the process of being swapped out and attempts to
541           compress them into a dynamically allocated RAM-based memory pool.
542           This can result in a significant I/O reduction on swap device and,
543           in the case where decompressing from RAM is faster that swap device
544           reads, can also improve workload performance.
545 
546           This is marked experimental because it is a new feature (as of
547           v3.11) that interacts heavily with memory reclaim.  While these
548           interactions don't cause any known issues on simple memory setups,
549           they have not be fully explored on the large set of potential
550           configurations and workloads that exist.
551 
552 config ZPOOL
553         tristate "Common API for compressed memory storage"
554         default n
555         help
556           Compressed memory storage API.  This allows using either zbud or
557           zsmalloc.
558 
559 config ZBUD
560         tristate "Low density storage for compressed pages"
561         default n
562         help
563           A special purpose allocator for storing compressed pages.
564           It is designed to store up to two compressed pages per physical
565           page.  While this design limits storage density, it has simple and
566           deterministic reclaim properties that make it preferable to a higher
567           density approach when reclaim will be used.
568 
569 config ZSMALLOC
570         tristate "Memory allocator for compressed pages"
571         depends on MMU
572         default n
573         help
574           zsmalloc is a slab-based memory allocator designed to store
575           compressed RAM pages.  zsmalloc uses virtual memory mapping
576           in order to reduce fragmentation.  However, this results in a
577           non-standard allocator interface where a handle, not a pointer, is
578           returned by an alloc().  This handle must be mapped in order to
579           access the allocated space.
580 
581 config PGTABLE_MAPPING
582         bool "Use page table mapping to access object in zsmalloc"
583         depends on ZSMALLOC
584         help
585           By default, zsmalloc uses a copy-based object mapping method to
586           access allocations that span two pages. However, if a particular
587           architecture (ex, ARM) performs VM mapping faster than copying,
588           then you should select this. This causes zsmalloc to use page table
589           mapping rather than copying for object mapping.
590 
591           You can check speed with zsmalloc benchmark:
592           https://github.com/spartacus06/zsmapbench
593 
594 config ZSMALLOC_STAT
595         bool "Export zsmalloc statistics"
596         depends on ZSMALLOC
597         select DEBUG_FS
598         help
599           This option enables code in the zsmalloc to collect various
600           statistics about whats happening in zsmalloc and exports that
601           information to userspace via debugfs.
602           If unsure, say N.
603 
604 config GENERIC_EARLY_IOREMAP
605         bool
606 
607 config MAX_STACK_SIZE_MB
608         int "Maximum user stack size for 32-bit processes (MB)"
609         default 80
610         range 8 256 if METAG
611         range 8 2048
612         depends on STACK_GROWSUP && (!64BIT || COMPAT)
613         help
614           This is the maximum stack size in Megabytes in the VM layout of 32-bit
615           user processes when the stack grows upwards (currently only on parisc
616           and metag arch). The stack will be located at the highest memory
617           address minus the given value, unless the RLIMIT_STACK hard limit is
618           changed to a smaller value in which case that is used.
619 
620           A sane initial value is 80 MB.
621 
622 # For architectures that support deferred memory initialisation
623 config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
624         bool
625 
626 config DEFERRED_STRUCT_PAGE_INIT
627         bool "Defer initialisation of struct pages to kswapd"
628         default n
629         depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
630         depends on MEMORY_HOTPLUG
631         help
632           Ordinarily all struct pages are initialised during early boot in a
633           single thread. On very large machines this can take a considerable
634           amount of time. If this option is set, large machines will bring up
635           a subset of memmap at boot and then initialise the rest in parallel
636           when kswapd starts. This has a potential performance impact on
637           processes running early in the lifetime of the systemm until kswapd
638           finishes the initialisation.
639 
640 config IDLE_PAGE_TRACKING
641         bool "Enable idle page tracking"
642         depends on SYSFS && MMU
643         select PAGE_EXTENSION if !64BIT
644         help
645           This feature allows to estimate the amount of user pages that have
646           not been touched during a given period of time. This information can
647           be useful to tune memory cgroup limits and/or for job placement
648           within a compute cluster.
649 
650           See Documentation/vm/idle_page_tracking.txt for more details.
651 
652 config ZONE_DEVICE
653         bool "Device memory (pmem, etc...) hotplug support" if EXPERT
654         default !ZONE_DMA
655         depends on !ZONE_DMA
656         depends on MEMORY_HOTPLUG
657         depends on MEMORY_HOTREMOVE
658         depends on X86_64 #arch_add_memory() comprehends device memory
659 
660         help
661           Device memory hotplug support allows for establishing pmem,
662           or other device driver discovered memory regions, in the
663           memmap. This allows pfn_to_page() lookups of otherwise
664           "device-physical" addresses which is needed for using a DAX
665           mapping in an O_DIRECT operation, among other things.
666 
667           If FS_DAX is enabled, then say Y.
668 
669 config FRAME_VECTOR
670         bool

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us