1mbind(2) System Calls Manual mbind(2)
2
6 mbind - set memory policy for a memory range
7
9 NUMA (Non-Uniform Memory Access) policy library (libnuma, -lnuma)
10
12 #include <numaif.h>
13 long mbind(void addr[.len], unsigned long len, int mode,
15 const unsigned long nodemask[(.maxnode + ULONG_WIDTH - 1)
16 / ULONG_WIDTH],
17 unsigned long maxnode, unsigned int flags);
18
20 mbind() sets the NUMA memory policy, which consists of a policy mode
21 and zero or more nodes, for the memory range starting with addr and
22 continuing for len bytes. The memory policy defines from which node
23 memory is allocated.
24 If the memory range specified by the addr and len arguments includes an
26 "anonymous" region of memory—that is a region of memory created using
27 the mmap(2) system call with the MAP_ANONYMOUS—or a memory-mapped file,
28 mapped using the mmap(2) system call with the MAP_PRIVATE flag, pages
29 will be allocated only according to the specified policy when the ap‐
30 plication writes (stores) to the page. For anonymous regions, an ini‐
31 tial read access will use a shared page in the kernel containing all
32 zeros. For a file mapped with MAP_PRIVATE, an initial read access will
33 allocate pages according to the memory policy of the thread that causes
34 the page to be allocated. This may not be the thread that called
35 mbind().
36 The specified policy will be ignored for any MAP_SHARED mappings in the
38 specified memory range. Rather the pages will be allocated according
39 to the memory policy of the thread that caused the page to be allo‐
40 cated. Again, this may not be the thread that called mbind().
41 If the specified memory range includes a shared memory region created
43 using the shmget(2) system call and attached using the shmat(2) system
44 call, pages allocated for the anonymous or shared memory region will be
45 allocated according to the policy specified, regardless of which
46 process attached to the shared memory segment causes the allocation.
47 If, however, the shared memory region was created with the SHM_HUGETLB
48 flag, the huge pages will be allocated according to the policy speci‐
49 fied only if the page allocation is caused by the process that calls
50 mbind() for that region.
51 By default, mbind() has an effect only for new allocations; if the
53 pages inside the range have been already touched before setting the
54 policy, then the policy has no effect. This default behavior may be
55 overridden by the MPOL_MF_MOVE and MPOL_MF_MOVE_ALL flags described be‐
56 low.
57 The mode argument must specify one of MPOL_DEFAULT, MPOL_BIND, MPOL_IN‐
59 TERLEAVE, MPOL_PREFERRED, or MPOL_LOCAL (which are described in detail
60 below). All policy modes except MPOL_DEFAULT require the caller to
61 specify the node or nodes to which the mode applies, via the nodemask
62 argument.
63 The mode argument