1 config SELECT_MEMORY_MODEL
2 def_bool y
3 depends on EXPERIMENTAL || 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 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 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 can not
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 def_bool n
105
106 #
107 # Architectecture 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 # eventually, we can have this option just 'select SPARSEMEM'
116 config MEMORY_HOTPLUG
117 bool "Allow for memory hot-add"
118 depends on SPARSEMEM && HOTPLUG && !SOFTWARE_SUSPEND
119
120 comment "Memory hotplug is currently incompatible with Software Suspend"
121 depends on SPARSEMEM && HOTPLUG && SOFTWARE_SUSPEND
122
123 # Heavily threaded applications may benefit from splitting the mm-wide
124 # page_table_lock, so that faults on different parts of the user address
125 # space can be handled with less contention: split it at this NR_CPUS.
126 # Default to 4 for wider testing, though 8 might be more appropriate.
127 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
128 # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
129 #
130 config SPLIT_PTLOCK_CPUS
131 int
132 default "4096" if ARM && !CPU_CACHE_VIPT
133 default "4096" if PARISC && !PA20
134 default "4"
135
136 #
137 # support for page migration
138 #
139 config MIGRATION
140 bool "Page migration"
141 def_bool y if NUMA
142 depends on SWAP && NUMA
143 help
144 Allows the migration of the physical location of pages of processes
145 while the virtual addresses are not changed. This is useful for
146 example on NUMA systems to put pages nearer to the processors accessing
147 the page.
This page was automatically generated by the
LXR engine.
Visit the LXR main site for more
information.