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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 an 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 | boolean | |
133 | ||
134 | config HAVE_MEMBLOCK_NODE_MAP | |
135 | boolean | |
136 | ||
137 | config ARCH_DISCARD_MEMBLOCK | |
138 | boolean | |
139 | ||
140 | config NO_BOOTMEM | |
141 | boolean | |
142 | ||
143 | config MEMORY_ISOLATION | |
144 | boolean | |
145 | ||
146 | config MOVABLE_NODE | |
147 | boolean "Enable to assign a node which has only movable memory" | |
148 | depends on HAVE_MEMBLOCK | |
149 | depends on NO_BOOTMEM | |
150 | depends on X86_64 | |
151 | depends on NUMA | |
152 | default n | |
153 | help | |
154 | Allow a node to have only movable memory. Pages used by the kernel, | |
155 | such as direct mapping pages cannot be migrated. So the corresponding | |
156 | memory device cannot be hotplugged. This option allows users to | |
157 | online all the memory of a node as movable memory so that the whole | |
158 | node can be hotplugged. Users who don't use the memory hotplug | |
159 | feature are fine with this option on since they don't online memory | |
160 | as movable. | |
161 | ||
162 | Say Y here if you want to hotplug a whole node. | |
163 | Say N here if you want kernel to use memory on all nodes evenly. | |
164 | ||
165 | # | |
166 | # Only be set on architectures that have completely implemented memory hotplug | |
167 | # feature. If you are not sure, don't touch it. | |
168 | # | |
169 | config HAVE_BOOTMEM_INFO_NODE | |
170 | def_bool n | |
171 | ||
172 | # eventually, we can have this option just 'select SPARSEMEM' | |
173 | config MEMORY_HOTPLUG | |
174 | bool "Allow for memory hot-add" | |
175 | depends on SPARSEMEM || X86_64_ACPI_NUMA | |
176 | depends on ARCH_ENABLE_MEMORY_HOTPLUG | |
177 | depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390) | |
178 | ||
179 | config MEMORY_HOTPLUG_SPARSE | |
180 | def_bool y | |
181 | depends on SPARSEMEM && MEMORY_HOTPLUG | |
182 | ||
183 | config MEMORY_HOTREMOVE | |
184 | bool "Allow for memory hot remove" | |
185 | select MEMORY_ISOLATION | |
186 | select HAVE_BOOTMEM_INFO_NODE if X86_64 | |
187 | depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE | |
188 | depends on MIGRATION | |
189 | ||
190 | # | |
191 | # If we have space for more page flags then we can enable additional | |
192 | # optimizations and functionality. | |
193 | # | |
194 | # Regular Sparsemem takes page flag bits for the sectionid if it does not | |
195 | # use a virtual memmap. Disable extended page flags for 32 bit platforms | |
196 | # that require the use of a sectionid in the page flags. | |
197 | # | |
198 | config PAGEFLAGS_EXTENDED | |
199 | def_bool y | |
200 | depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM | |
201 | ||
202 | # Heavily threaded applications may benefit from splitting the mm-wide | |
203 | # page_table_lock, so that faults on different parts of the user address | |
204 | # space can be handled with less contention: split it at this NR_CPUS. | |
205 | # Default to 4 for wider testing, though 8 might be more appropriate. | |
206 | # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. | |
207 | # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. | |
208 | # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. | |
209 | # | |
210 | config SPLIT_PTLOCK_CPUS | |
211 | int | |
212 | default "999999" if ARM && !CPU_CACHE_VIPT | |
213 | default "999999" if PARISC && !PA20 | |
214 | default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC | |
215 | default "4" | |
216 | ||
217 | # | |
218 | # support for memory balloon compaction | |
219 | config BALLOON_COMPACTION | |
220 | bool "Allow for balloon memory compaction/migration" | |
221 | def_bool y | |
222 | depends on COMPACTION && VIRTIO_BALLOON | |
223 | help | |
224 | Memory fragmentation introduced by ballooning might reduce | |
225 | significantly the number of 2MB contiguous memory blocks that can be | |
226 | used within a guest, thus imposing performance penalties associated | |
227 | with the reduced number of transparent huge pages that could be used | |
228 | by the guest workload. Allowing the compaction & migration for memory | |
229 | pages enlisted as being part of memory balloon devices avoids the | |
230 | scenario aforementioned and helps improving memory defragmentation. | |
231 | ||
232 | # | |
233 | # support for memory compaction | |
234 | config COMPACTION | |
235 | bool "Allow for memory compaction" | |
236 | def_bool y | |
237 | select MIGRATION | |
238 | depends on MMU | |
239 | help | |
240 | Allows the compaction of memory for the allocation of huge pages. | |
241 | ||
242 | # | |
243 | # support for page migration | |
244 | # | |
245 | config MIGRATION | |
246 | bool "Page migration" | |
247 | def_bool y | |
248 | depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA | |
249 | help | |
250 | Allows the migration of the physical location of pages of processes | |
251 | while the virtual addresses are not changed. This is useful in | |
252 | two situations. The first is on NUMA systems to put pages nearer | |
253 | to the processors accessing. The second is when allocating huge | |
254 | pages as migration can relocate pages to satisfy a huge page | |
255 | allocation instead of reclaiming. | |
256 | ||
257 | config PHYS_ADDR_T_64BIT | |
258 | def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT | |
259 | ||
260 | config ZONE_DMA_FLAG | |
261 | int | |
262 | default "0" if !ZONE_DMA | |
263 | default "1" | |
264 | ||
265 | config BOUNCE | |
266 | bool "Enable bounce buffers" | |
267 | default y | |
268 | depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) | |
269 | help | |
270 | Enable bounce buffers for devices that cannot access | |
271 | the full range of memory available to the CPU. Enabled | |
272 | by default when ZONE_DMA or HIGHMEM is selected, but you | |
273 | may say n to override this. | |
274 | ||
275 | # On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often | |
276 | # have more than 4GB of memory, but we don't currently use the IOTLB to present | |
277 | # a 32-bit address to OHCI. So we need to use a bounce pool instead. | |
278 | # | |
279 | # We also use the bounce pool to provide stable page writes for jbd. jbd | |
280 | # initiates buffer writeback without locking the page or setting PG_writeback, | |
281 | # and fixing that behavior (a second time; jbd2 doesn't have this problem) is | |
282 | # a major rework effort. Instead, use the bounce buffer to snapshot pages | |
283 | # (until jbd goes away). The only jbd user is ext3. | |
284 | config NEED_BOUNCE_POOL | |
285 | bool | |
286 | default y if (TILE && USB_OHCI_HCD) || (BLK_DEV_INTEGRITY && JBD) | |
287 | ||
288 | config NR_QUICK | |
289 | int | |
290 | depends on QUICKLIST | |
291 | default "2" if AVR32 | |
292 | default "1" | |
293 | ||
294 | config VIRT_TO_BUS | |
295 | bool | |
296 | help | |
297 | An architecture should select this if it implements the | |
298 | deprecated interface virt_to_bus(). All new architectures | |
299 | should probably not select this. | |
300 | ||
301 | ||
302 | config MMU_NOTIFIER | |
303 | bool | |
304 | ||
305 | config KSM | |
306 | bool "Enable KSM for page merging" | |
307 | depends on MMU | |
308 | help | |
309 | Enable Kernel Samepage Merging: KSM periodically scans those areas | |
310 | of an application's address space that an app has advised may be | |
311 | mergeable. When it finds pages of identical content, it replaces | |
312 | the many instances by a single page with that content, so | |
313 | saving memory until one or another app needs to modify the content. | |
314 | Recommended for use with KVM, or with other duplicative applications. | |
315 | See Documentation/vm/ksm.txt for more information: KSM is inactive | |
316 | until a program has madvised that an area is MADV_MERGEABLE, and | |
317 | root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). | |
318 | ||
319 | config DEFAULT_MMAP_MIN_ADDR | |
320 | int "Low address space to protect from user allocation" | |
321 | depends on MMU | |
322 | default 4096 | |
323 | help | |
324 | This is the portion of low virtual memory which should be protected | |
325 | from userspace allocation. Keeping a user from writing to low pages | |
326 | can help reduce the impact of kernel NULL pointer bugs. | |
327 | ||
328 | For most ia64, ppc64 and x86 users with lots of address space | |
329 | a value of 65536 is reasonable and should cause no problems. | |
330 | On arm and other archs it should not be higher than 32768. | |
331 | Programs which use vm86 functionality or have some need to map | |
332 | this low address space will need CAP_SYS_RAWIO or disable this | |
333 | protection by setting the value to 0. | |
334 | ||
335 | This value can be changed after boot using the | |
336 | /proc/sys/vm/mmap_min_addr tunable. | |
337 | ||
338 | config ARCH_SUPPORTS_MEMORY_FAILURE | |
339 | bool | |
340 | ||
341 | config MEMORY_FAILURE | |
342 | depends on MMU | |
343 | depends on ARCH_SUPPORTS_MEMORY_FAILURE | |
344 | bool "Enable recovery from hardware memory errors" | |
345 | select MEMORY_ISOLATION | |
346 | help | |
347 | Enables code to recover from some memory failures on systems | |
348 | with MCA recovery. This allows a system to continue running | |
349 | even when some of its memory has uncorrected errors. This requires | |
350 | special hardware support and typically ECC memory. | |
351 | ||
352 | config HWPOISON_INJECT | |
353 | tristate "HWPoison pages injector" | |
354 | depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS | |
355 | select PROC_PAGE_MONITOR | |
356 | ||
357 | config NOMMU_INITIAL_TRIM_EXCESS | |
358 | int "Turn on mmap() excess space trimming before booting" | |
359 | depends on !MMU | |
360 | default 1 | |
361 | help | |
362 | The NOMMU mmap() frequently needs to allocate large contiguous chunks | |
363 | of memory on which to store mappings, but it can only ask the system | |
364 | allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently | |
365 | more than it requires. To deal with this, mmap() is able to trim off | |
366 | the excess and return it to the allocator. | |
367 | ||
368 | If trimming is enabled, the excess is trimmed off and returned to the | |
369 | system allocator, which can cause extra fragmentation, particularly | |
370 | if there are a lot of transient processes. | |
371 | ||
372 | If trimming is disabled, the excess is kept, but not used, which for | |
373 | long-term mappings means that the space is wasted. | |
374 | ||
375 | Trimming can be dynamically controlled through a sysctl option | |
376 | (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of | |
377 | excess pages there must be before trimming should occur, or zero if | |
378 | no trimming is to occur. | |
379 | ||
380 | This option specifies the initial value of this option. The default | |
381 | of 1 says that all excess pages should be trimmed. | |
382 | ||
383 | See Documentation/nommu-mmap.txt for more information. | |
384 | ||
385 | config TRANSPARENT_HUGEPAGE | |
386 | bool "Transparent Hugepage Support" | |
387 | depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE | |
388 | select COMPACTION | |
389 | help | |
390 | Transparent Hugepages allows the kernel to use huge pages and | |
391 | huge tlb transparently to the applications whenever possible. | |
392 | This feature can improve computing performance to certain | |
393 | applications by speeding up page faults during memory | |
394 | allocation, by reducing the number of tlb misses and by speeding | |
395 | up the pagetable walking. | |
396 | ||
397 | If memory constrained on embedded, you may want to say N. | |
398 | ||
399 | choice | |
400 | prompt "Transparent Hugepage Support sysfs defaults" | |
401 | depends on TRANSPARENT_HUGEPAGE | |
402 | default TRANSPARENT_HUGEPAGE_ALWAYS | |
403 | help | |
404 | Selects the sysfs defaults for Transparent Hugepage Support. | |
405 | ||
406 | config TRANSPARENT_HUGEPAGE_ALWAYS | |
407 | bool "always" | |
408 | help | |
409 | Enabling Transparent Hugepage always, can increase the | |
410 | memory footprint of applications without a guaranteed | |
411 | benefit but it will work automatically for all applications. | |
412 | ||
413 | config TRANSPARENT_HUGEPAGE_MADVISE | |
414 | bool "madvise" | |
415 | help | |
416 | Enabling Transparent Hugepage madvise, will only provide a | |
417 | performance improvement benefit to the applications using | |
418 | madvise(MADV_HUGEPAGE) but it won't risk to increase the | |
419 | memory footprint of applications without a guaranteed | |
420 | benefit. | |
421 | endchoice | |
422 | ||
423 | config CROSS_MEMORY_ATTACH | |
424 | bool "Cross Memory Support" | |
425 | depends on MMU | |
426 | default y | |
427 | help | |
428 | Enabling this option adds the system calls process_vm_readv and | |
429 | process_vm_writev which allow a process with the correct privileges | |
430 | to directly read from or write to to another process's address space. | |
431 | See the man page for more details. | |
432 | ||
433 | # | |
434 | # UP and nommu archs use km based percpu allocator | |
435 | # | |
436 | config NEED_PER_CPU_KM | |
437 | depends on !SMP | |
438 | bool | |
439 | default y | |
440 | ||
441 | config CLEANCACHE | |
442 | bool "Enable cleancache driver to cache clean pages if tmem is present" | |
443 | default n | |
444 | help | |
445 | Cleancache can be thought of as a page-granularity victim cache | |
446 | for clean pages that the kernel's pageframe replacement algorithm | |
447 | (PFRA) would like to keep around, but can't since there isn't enough | |
448 | memory. So when the PFRA "evicts" a page, it first attempts to use | |
449 | cleancache code to put the data contained in that page into | |
450 | "transcendent memory", memory that is not directly accessible or | |
451 | addressable by the kernel and is of unknown and possibly | |
452 | time-varying size. And when a cleancache-enabled | |
453 | filesystem wishes to access a page in a file on disk, it first | |
454 | checks cleancache to see if it already contains it; if it does, | |
455 | the page is copied into the kernel and a disk access is avoided. | |
456 | When a transcendent memory driver is available (such as zcache or | |
457 | Xen transcendent memory), a significant I/O reduction | |
458 | may be achieved. When none is available, all cleancache calls | |
459 | are reduced to a single pointer-compare-against-NULL resulting | |
460 | in a negligible performance hit. | |
461 | ||
462 | If unsure, say Y to enable cleancache | |
463 | ||
464 | config FRONTSWAP | |
465 | bool "Enable frontswap to cache swap pages if tmem is present" | |
466 | depends on SWAP | |
467 | default n | |
468 | help | |
469 | Frontswap is so named because it can be thought of as the opposite | |
470 | of a "backing" store for a swap device. The data is stored into | |
471 | "transcendent memory", memory that is not directly accessible or | |
472 | addressable by the kernel and is of unknown and possibly | |
473 | time-varying size. When space in transcendent memory is available, | |
474 | a significant swap I/O reduction may be achieved. When none is | |
475 | available, all frontswap calls are reduced to a single pointer- | |
476 | compare-against-NULL resulting in a negligible performance hit | |
477 | and swap data is stored as normal on the matching swap device. | |
478 | ||
479 | If unsure, say Y to enable frontswap. | |
480 | ||
481 | config ZBUD | |
482 | tristate | |
483 | default n | |
484 | help | |
485 | A special purpose allocator for storing compressed pages. | |
486 | It is designed to store up to two compressed pages per physical | |
487 | page. While this design limits storage density, it has simple and | |
488 | deterministic reclaim properties that make it preferable to a higher | |
489 | density approach when reclaim will be used. | |
490 | ||
491 | config ZSWAP | |
492 | bool "Compressed cache for swap pages (EXPERIMENTAL)" | |
493 | depends on FRONTSWAP && CRYPTO=y | |
494 | select CRYPTO_LZO | |
495 | select ZBUD | |
496 | default n | |
497 | help | |
498 | A lightweight compressed cache for swap pages. It takes | |
499 | pages that are in the process of being swapped out and attempts to | |
500 | compress them into a dynamically allocated RAM-based memory pool. | |
501 | This can result in a significant I/O reduction on swap device and, | |
502 | in the case where decompressing from RAM is faster that swap device | |
503 | reads, can also improve workload performance. | |
504 | ||
505 | This is marked experimental because it is a new feature (as of | |
506 | v3.11) that interacts heavily with memory reclaim. While these | |
507 | interactions don't cause any known issues on simple memory setups, | |
508 | they have not be fully explored on the large set of potential | |
509 | configurations and workloads that exist. | |
510 | ||
511 | config MEM_SOFT_DIRTY | |
512 | bool "Track memory changes" | |
513 | depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY | |
514 | select PROC_PAGE_MONITOR | |
515 | help | |
516 | This option enables memory changes tracking by introducing a | |
517 | soft-dirty bit on pte-s. This bit it set when someone writes | |
518 | into a page just as regular dirty bit, but unlike the latter | |
519 | it can be cleared by hands. | |
520 | ||
521 | See Documentation/vm/soft-dirty.txt for more details. |