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NUMA(3)                    Linux Programmer's Manual                   NUMA(3)

NAME
       numa - NUMA policy library

SYNOPSIS
       #include <numa.h>

       cc ... -lnuma

       int numa_available(void);

       int numa_max_possible_node(void);
       int numa_num_possible_nodes();

       int numa_max_node(void);
       int numa_num_configured_nodes();
       struct bitmask *numa_get_mems_allowed(void);

       int numa_num_configured_cpus(void);
       struct bitmask *numa_all_nodes_ptr;
       struct bitmask *numa_no_nodes_ptr;
       struct bitmask *numa_all_cpus_ptr;

       int numa_num_task_cpus();
       int numa_num_task_nodes();

       int numa_parse_bitmap(char *line , struct bitmask *mask);
       struct bitmask *numa_parse_nodestring(const char *string);
       struct bitmask *numa_parse_nodestring_all(const char *string);
       struct bitmask *numa_parse_cpustring(const char *string);
       struct bitmask *numa_parse_cpustring_all(const char *string);

       long numa_node_size(int node, long *freep);
       long long numa_node_size64(int node, long long *freep);

       int numa_preferred(void);
       void numa_set_preferred(int node);
       int numa_get_interleave_node(void);
       struct bitmask *numa_get_interleave_mask(void);
       void numa_set_interleave_mask(struct bitmask *nodemask);
       void  numa_interleave_memory(void  *start,  size_t size, struct bitmask
       *nodemask);
       void numa_bind(struct bitmask *nodemask);
       void numa_set_localalloc(void);
       void numa_set_membind(struct bitmask *nodemask);
       struct bitmask *numa_get_membind(void);

       void *numa_alloc_onnode(size_t size, int node);
       void *numa_alloc_local(size_t size);
       void *numa_alloc_interleaved(size_t size);
       void *numa_alloc_interleaved_subset(size_t size,  struct bitmask *node-
       mask); void *numa_alloc(size_t size);
       void *numa_realloc(void *old_addr, size_t old_size, size_t new_size);
       void numa_free(void *start, size_t size);

       int numa_run_on_node(int node);
       int numa_run_on_node_mask(struct bitmask *nodemask);
       int numa_run_on_node_mask_all(struct bitmask *nodemask);
       struct bitmask *numa_get_run_node_mask(void);

       void numa_tonode_memory(void *start, size_t size, int node);
       void  numa_tonodemask_memory(void  *start,  size_t size, struct bitmask
       *nodemask);
       void numa_setlocal_memory(void *start, size_t size);
       void numa_police_memory(void *start, size_t size);
       void numa_set_bind_policy(int strict);
       void numa_set_strict(int strict);

       int numa_distance(int node1, int node2);

       int numa_sched_getaffinity(pid_t pid, struct bitmask *mask);
       int numa_sched_setaffinity(pid_t pid, struct bitmask *mask);
       int numa_node_to_cpus(int node, struct bitmask *mask);
       int numa_node_of_cpu(int cpu);

       struct bitmask *numa_allocate_cpumask();

       void numa_free_cpumask();
       struct bitmask *numa_allocate_nodemask();

       void numa_free_nodemask();
       struct bitmask *numa_bitmask_alloc(unsigned int n);
       struct bitmask *numa_bitmask_clearall(struct bitmask *bmp);
       struct bitmask *numa_bitmask_clearbit(struct bitmask *bmp, unsigned int
       n);
       int numa_bitmask_equal(const struct bitmask *bmp1, const struct bitmask
       *bmp2);
       void numa_bitmask_free(struct bitmask *bmp);
       int numa_bitmask_isbitset(const struct bitmask *bmp, unsigned int n);
       unsigned int numa_bitmask_nbytes(struct bitmask *bmp);
       struct bitmask *numa_bitmask_setall(struct bitmask *bmp);
       struct bitmask *numa_bitmask_setbit(struct bitmask *bmp,  unsigned  int
       n);
       void  copy_bitmask_to_nodemask(struct  bitmask  *bmp, nodemask_t *node-
       mask)
       void  copy_nodemask_to_bitmask(nodemask_t  *nodemask,  struct   bitmask
       *bmp)
       void  copy_bitmask_to_bitmask(struct  bitmask  *bmpfrom, struct bitmask
       *bmpto)
       unsigned int numa_bitmask_weight(const struct bitmask *bmp )

       int numa_move_pages(int pid, unsigned long count, void  **pages,  const
       int *nodes, int *status, int flags);
       int  numa_migrate_pages(int pid, struct bitmask *fromnodes, struct bit-
       mask *tonodes);

       void numa_error(char *where);

       extern int numa_exit_on_error;
       extern int numa_exit_on_warn;
       void numa_warn(int number, char *where, ...);

DESCRIPTION
       The libnuma library offers a simple programming interface to  the  NUMA
       (Non  Uniform Memory Access) policy supported by the Linux kernel. On a
       NUMA architecture some memory areas have different latency or bandwidth
       than others.

       Available  policies  are  page interleaving (i.e., allocate in a round-
       robin fashion from all, or a subset, of the nodes on the system),  pre-
       ferred  node  allocation  (i.e.,  preferably  allocate  on a particular
       node), local allocation (i.e., allocate on the node on which  the  task
       is  currently  executing),  or allocation only on specific nodes (i.e.,
       allocate on some subset of the available nodes).  It is  also  possible
       to bind tasks to specific nodes.

       Numa memory allocation policy may be specified as a per-task attribute,
       that is inherited by children tasks and processes, or as  an  attribute
       of  a  range  of  process  virtual address space.  Numa memory policies
       specified for a range of virtual address space are shared by all  tasks
       in the process.  Further more, memory policies specified for a range of
       a shared memory attached using shmat(2) or mmap(2) from shmfs/hugetlbfs
       are  shared  by all processes that attach to that region.  Memory poli-
       cies for shared disk backed file mappings are currently ignored.

       The default memory allocation policy for tasks and all memory range  is
       local  allocation.   This assumes that no ancestor has installed a non-
       default policy.

       For setting a specific policy globally for all memory allocations in  a
       process  and its children it is easiest to start it with the numactl(8)
       utility. For more finegrained policy inside an application this library
       can be used.

       All  numa  memory  allocation  policy  only takes effect when a page is
       actually faulted into the address space of a process by  accessing  it.
       The numa_alloc_* functions take care of this automatically.

       A  node  is  defined  as an area where all memory has the same speed as
       seen from a particular CPU.  A node can contain multiple CPUs.   Caches
       are ignored for this definition.

       Most  functions in this library are only concerned about numa nodes and
       their  memory.   The  exceptions  to  this  are:   numa_node_to_cpus(),
       numa_node_of_cpu(),           numa_bind(),          numa_run_on_node(),
       numa_run_on_node_mask(),        numa_run_on_node_mask_all(),        and
       numa_get_run_node_mask().   These  functions deal with the CPUs associ-
       ated with numa nodes.  See the descriptions below for more information.

       Some of these functions accept or return a pointer to  struct  bitmask.
       A  struct  bitmask  controls a bit map of arbitrary length containing a
       bit    representation    of    nodes.     The    predefined    variable
       numa_all_nodes_ptr  points  to  a bit mask that has all available nodes
       set; numa_no_nodes_ptr points to the empty set.

       Before any other calls in this library  can  be  used  numa_available()
       must  be  called. If it returns -1, all other functions in this library
       are undefined.

       numa_max_possible_node() returns the number  of  the  highest  possible
       node in a system.  In other words, the size of a kernel type nodemask_t
       (in bits) minus 1.  This number can be gotten by calling  numa_num_pos-
       sible_nodes() and subtracting 1.

       numa_num_possible_nodes()  returns the size of kernel's node mask (ker-
       nel type nodemask_t).  In other words, large enough  to  represent  the
       maximum number of nodes that the kernel can handle. This will match the
       kernel's   MAX_NUMNODES   value.    This   count   is   derived    from
       /proc/self/status, field Mems_allowed.

       numa_max_node()  returns  the highest node number available on the cur-
       rent system.  (See the node  numbers  in  /sys/devices/system/node/  ).
       Also see numa_num_configured_nodes().

       numa_num_configured_nodes()  returns  the number of memory nodes in the
       system. This count includes any nodes that are currently disabled. This
       count  is  derived  from  the node numbers in /sys/devices/system/node.
       (Depends on the kernel being configured with /sys (CONFIG_SYSFS)).

       numa_get_mems_allowed() returns  the  mask  of  nodes  from  which  the
       process  is  allowed to allocate memory in it's current cpuset context.
       Any nodes that are not included in the returned bitmask will be ignored
       in any of the following libnuma memory policy calls.

       numa_num_configured_cpus()  returns  the  number of cpus in the system.
       This count includes any cpus that are currently disabled. This count is
       derived  from the cpu numbers in /sys/devices/system/cpu. If the kernel
       is configured without /sys (CONFIG_SYSFS=n) then it falls back to using
       the number of online cpus.

       numa_all_nodes_ptr points to a bitmask that is allocated by the library
       with bits representing all nodes on which the calling task may allocate
       memory.   This  set  may be up to all nodes on the system, or up to the
       nodes in the current cpuset.  The bitmask is allocated  by  a  call  to
       numa_allocate_nodemask()  using size numa_max_possible_node().  The set
       of  nodes  to  record  is   derived   from   /proc/self/status,   field
       "Mems_allowed".  The user should not alter this bitmask.

       numa_no_nodes_ptr  points to a bitmask that is allocated by the library
       and left all zeroes.  The bitmask is allocated by a call to  numa_allo-
       cate_nodemask()  using  size numa_max_possible_node().  The user should
       not alter this bitmask.

       numa_all_cpus_ptr points to a bitmask that is allocated by the  library
       with  bits representing all cpus on which the calling task may execute.
       This set may be up to all cpus on the system, or up to the cpus in  the
       current  cpuset.   The  bitmask  is  allocated  by a call to numa_allo-
       cate_cpumask() using size numa_num_possible_cpus().  The set of cpus to
       record  is  derived  from /proc/self/status, field "Cpus_allowed".  The
       user should not alter this bitmask.

       numa_num_task_cpus() returns the number of cpus that the  calling  task
       is  allowed to use.  This count is derived from the map /proc/self/sta-
       tus, field "Cpus_allowed". Also see the bitmask numa_all_cpus_ptr.

       numa_num_task_nodes() returns the number of nodes on which the  calling
       task is allowed to allocate memory.  This count is derived from the map
       /proc/self/status,  field  "Mems_allowed".   Also   see   the   bitmask
       numa_all_nodes_ptr.

       numa_parse_bitmap()  parses  line , which is a character string such as
       found in /sys/devices/system/node/nodeN/cpumap into  a  bitmask  struc-
       ture.  The string contains the hexadecimal representation of a bit map.
       The bitmask may be allocated with numa_allocate_cpumask().  Returns   0
       on  success.  Returns -1 on failure.  This function is probably of lit-
       tle use to a user application, but it is used by libnuma internally.

       numa_parse_nodestring() parses a character string list of nodes into  a
       bit  mask.  The bit mask is allocated by numa_allocate_nodemask().  The
       string is a comma-separated list of node numbers  or  node  ranges.   A
       leading  ! can be used to indicate "not" this list (in other words, all
       nodes except this list), and a leading + can be used to  indicate  that
       the  node  numbers  in the list are relative to the task's cpuset.  The
       string can be "all" to specify all  (  numa_num_task_nodes()  )  nodes.
       Node   numbers   are   limited  by  the  number  in  the  system.   See
       numa_max_node() and numa_num_configured_nodes().
       Examples:  1-5,7,10   !4-5   +0-3
       If the string is of 0 length, bitmask  numa_no_nodes_ptr  is  returned.
       Returns 0 if the string is invalid.

       numa_parse_nodestring_all()  is  similar to numa_parse_nodestring , but
       can parse all possible nodes, not only current nodeset.

       numa_parse_cpustring() parses a character string list of  cpus  into  a
       bit  mask.   The bit mask is allocated by numa_allocate_cpumask().  The
       string is a comma-separated list of cpu numbers or cpu ranges.  A lead-
       ing ! can be used to indicate "not" this list (in other words, all cpus
       except this list), and a leading + can be used to indicate that the cpu
       numbers  in the list are relative to the task's cpuset.  The string can
       be "all" to specify all ( numa_num_task_cpus() ) cpus.  Cpu numbers are
       limited  by  the  number  in  the system.  See numa_num_task_cpus() and
       numa_num_configured_cpus().
       Examples:  1-5,7,10   !4-5   +0-3
       Returns 0 if the string is invalid.

       numa_parse_cpustring_all() is similar to numa_parse_cpustring , but can
       parse all possible cpus, not only current cpuset.

       numa_node_size()  returns  the  memory  size of a node. If the argument
       freep is not NULL, it used to return the amount of free memory  on  the
       node.  On error it returns -1.

       numa_node_size64()  works  the  same as numa_node_size() except that it
       returns values as long long instead of long.  This is useful on  32-bit
       architectures with large nodes.

       numa_preferred()  returns the preferred node of the current task.  This
       is the node on which the kernel  preferably  allocates  memory,  unless
       some other policy overrides this.

       numa_set_preferred()  sets  the  preferred node for the current task to
       node.  The system will attempt to allocate memory  from  the  preferred
       node,  but  will  fall back to other nodes if no memory is available on
       the the preferred node.  Passing a node of -1 argument specifies  local
       allocation and is equivalent to calling numa_set_localalloc().

       numa_get_interleave_mask()  returns  the current interleave mask if the
       task's memory allocation policy is page interleaved.   Otherwise,  this
       function returns an empty mask.

       numa_set_interleave_mask() sets the memory interleave mask for the cur-
       rent task to nodemask.  All new memory allocations are page interleaved
       over  all  nodes in the interleave mask. Interleaving can be turned off
       again by passing an empty mask (numa_no_nodes).  The page  interleaving
       only occurs on the actual page fault that puts a new page into the cur-
       rent address space. It is also only a hint: the kernel will  fall  back
       to other nodes if no memory is available on the interleave target.

       numa_interleave_memory()  interleaves size bytes of memory page by page
       from start on nodes specified in nodemask.  The size argument  will  be
       rounded up to a multiple of the system page size.  If nodemask contains
       nodes that are externally denied to this process, this call will  fail.
       This  is  a  lower  level  function to interleave allocated but not yet
       faulted in memory. Not yet faulted in means  the  memory  is  allocated
       using  mmap(2)  or  shmat(2),  but has not been accessed by the current
       process yet. The memory is page interleaved to all nodes  specified  in
       nodemask.  Normally numa_alloc_interleaved() should be used for private
       memory instead, but this function is useful  to  handle  shared  memory
       areas.  To  be  useful  the  memory area should be several megabytes at
       least  (or  tens  of  megabytes   of   hugetlbfs   mappings)   If   the
       numa_set_strict()  flag  is  true  then  the  operation  will  cause  a
       numa_error if there were already pages in the mapping that do not  fol-
       low the policy.

       numa_bind() binds the current task and its children to the nodes speci-
       fied in nodemask.  They will only run on  the  CPUs  of  the  specified
       nodes  and only be able to allocate memory from them.  This function is
       equivalent  to  calling  numa_run_on_node_mask(nodemask)  followed   by
       numa_set_membind(nodemask).   If  tasks  should  be bound to individual
       CPUs  inside   nodes   consider   using   numa_node_to_cpus   and   the
       sched_setaffinity(2) syscall.

       numa_set_localalloc() sets the memory allocation policy for the calling
       task to local allocation.  In this mode, the preferred node for  memory
       allocation  is  effectively the node where the task is executing at the
       time of a page allocation.

       numa_set_membind() sets the memory allocation mask.  The task will only
       allocate memory from the nodes set in nodemask.  Passing an empty node-
       mask or a nodemask that contains nodes other than  those  in  the  mask
       returned by numa_get_mems_allowed() will result in an error.

       numa_get_membind() returns the mask of nodes from which memory can cur-
       rently be allocated.  If the returned mask is equal to  numa_all_nodes,
       then memory allocation is allowed from all nodes.

       numa_alloc_onnode()  allocates  memory  on  a  specific node.  The size
       argument will be rounded up to a multiple of the system page size.   if
       the specified node is externally denied to this process, this call will
       fail.  This function is relatively slow compared to the malloc(3), fam-
       ily  of  functions.   The  memory  must  be freed with numa_free().  On
       errors NULL is returned.

       numa_alloc_local() allocates size bytes of memory on  the  local  node.
       The  size  argument will be rounded up to a multiple of the system page
       size.  This function is relatively slow compared to the malloc(3)  fam-
       ily  of  functions.   The  memory  must  be freed with numa_free().  On
       errors NULL is returned.

       numa_alloc_interleaved() allocates size bytes  of  memory  page  inter-
       leaved  on  all nodes. This function is relatively slow and should only
       be used for large areas consisting of multiple pages. The  interleaving
       works  at  page  level  and  will  only show an effect when the area is
       large.  The allocated memory must be freed with numa_free().  On error,
       NULL is returned.

       numa_alloc_interleaved_subset() attempts to allocate size bytes of mem-
       ory page interleaved on all nodes.  The size argument will  be  rounded
       up to a multiple of the system page size.  The nodes on which a process
       is allowed to allocate memory may be constrained externally.   If  this
       is  the case, this function may fail.  This function is relatively slow
       compare to malloc(3), family of functions and should only be  used  for
       large  areas  consisting  of multiple pages.  The interleaving works at
       page level and will only show an effect when the area  is  large.   The
       allocated  memory  must  be  freed with numa_free().  On error, NULL is
       returned.

       numa_alloc() allocates size bytes of memory with the current NUMA  pol-
       icy.   The size argument will be rounded up to a multiple of the system
       page size.  This function is relatively slow compare to  the  malloc(3)
       family  of  functions.   The memory must be freed with numa_free().  On
       errors NULL is returned.

       numa_realloc() changes the size  of  the  memory  area  pointed  to  by
       old_addr  from  old_size  to  new_size.   The memory area pointed to by
       old_addr must have been allocated with one  of  the  numa_alloc*  func-
       tions.   The  new_size  will  be rounded up to a multiple of the system
       page size. The contents of the memory area will  be  unchanged  to  the
       minimum of the old and new sizes; newly allocated memory will be unini-
       tialized. The memory policy (and node  bindings)  associated  with  the
       original  memory  area will be preserved in the resized area. For exam-
       ple, if the initial area was allocated with a call  to  numa_alloc_onn-
       ode(),  then  the new pages (if the area is enlarged) will be allocated
       on the same node.  However, if no memory policy was set for the  origi-
       nal  area, then numa_realloc() cannot guarantee that the new pages will
       be allocated on the same node. On success, the address of  the  resized
       area  is  returned  (which  might be different from that of the initial
       area), otherwise NULL is returned and errno  is  set  to  indicate  the
       error.  The  pointer returned by numa_realloc() is suitable for passing
       to numa_free().

       numa_free() frees size bytes of memory starting at start, allocated  by
       the numa_alloc_* functions above.  The size argument will be rounded up
       to a multiple of the system page size.

       numa_run_on_node() runs the current task and its children on a specific
       node.  They  will  not  migrate  to  CPUs of other nodes until the node
       affinity is reset with a new call to numa_run_on_node_mask().   Passing
       -1 permits the kernel to schedule on all nodes again.  On success, 0 is
       returned; on error -1 is returned, and errno is  set  to  indicate  the
       error.

       numa_run_on_node_mask()  runs the current task and its children only on
       nodes specified in nodemask.  They will not migrate to  CPUs  of  other
       nodes   until   the   node  affinity  is  reset  with  a  new  call  to
       numa_run_on_node_mask() or numa_run_on_node().  Passing  numa_all_nodes
       permits  the  kernel  to schedule on all nodes again.  On success, 0 is
       returned; on error -1 is returned, and errno is  set  to  indicate  the
       error.

       numa_run_on_node_mask_all() runs the current task and its children only
       on nodes specified in nodemask like numa_run_on_node_mask  but  without
       any cpuset awareness.

       numa_get_run_node_mask()  returns  a  mask of CPUs on which the current
       task is allowed to run.

       numa_tonode_memory() put memory on a  specific  node.  The  constraints
       described for numa_interleave_memory() apply here too.

       numa_tonodemask_memory()  put  memory  on  a specific set of nodes. The
       constraints described for numa_interleave_memory() apply here too.

       numa_setlocal_memory() locates memory on the  current  node.  The  con-
       straints described for numa_interleave_memory() apply here too.

       numa_police_memory()  locates  memory with the current NUMA policy. The
       constraints described for numa_interleave_memory() apply here too.

       numa_distance() reports the distance in the  machine  topology  between
       two  nodes.   The  factors  are a multiple of 10. It returns 0 when the
       distance cannot be determined.  A  node  has  distance  10  to  itself.
       Reporting  the  distance  requires  a Linux kernel version of 2.6.10 or
       newer.

       numa_set_bind_policy() specifies whether calls that bind  memory  to  a
       specific  node should use the preferred policy or a strict policy.  The
       preferred policy allows the kernel to allocate memory  on  other  nodes
       when  there  isn't enough free on the target node. strict will fail the
       allocation in that case.  Setting the argument to specifies  strict,  0
       preferred.  Note that specifying more than one node non strict may only
       use the first node in some kernel versions.

       numa_set_strict() sets a flag that says whether the functions  allocat-
       ing  on specific nodes should use use a strict policy. Strict means the
       allocation will fail if the memory cannot be allocated  on  the  target
       node.   Default operation is to fall back to other nodes.  This doesn't
       apply to interleave and default.

       numa_get_interleave_node() is used by libnuma internally. It is  proba-
       bly  not useful for user applications.  It uses the MPOL_F_NODE flag of
       the get_mempolicy system call, which is not  intended  for  application
       use (its operation may change or be removed altogether in future kernel
       versions). See get_mempolicy(2).

       numa_pagesize() returns the number of bytes in page. This  function  is
       simply  a  fast alternative to repeated calls to the getpagesize system
       call.  See getpagesize(2).

       numa_sched_getaffinity() retrieves a bitmask of the  cpus  on  which  a
       task  may run.  The task is specified by pid.  Returns the return value
       of the sched_getaffinity system call.  See  sched_getaffinity(2).   The
       bitmask  must  be at least the size of the kernel's cpu mask structure.
       Use numa_allocate_cpumask() to allocate it.  Test the bits in the  mask
       by calling numa_bitmask_isbitset().

       numa_sched_setaffinity()  sets  a  task's  allowed cpu's to those cpu's
       specified in mask.  The task is specified by pid.  Returns  the  return
       value  of the sched_setaffinity system call.  See sched_setaffinity(2).
       You may allocate the bitmask with numa_allocate_cpumask().  Or the bit-
       mask  may be smaller than the kernel's cpu mask structure. For example,
       call  numa_bitmask_alloc()  using  a  maximum  number  of   cpus   from
       numa_num_configured_cpus().   Set  the  bits  in  the  mask  by calling
       numa_bitmask_setbit().

       numa_node_to_cpus() converts a node number to a bitmask  of  CPUs.  The
       user  must  pass  a bitmask structure with a mask buffer long enough to
       represent all possible cpu's.  Use  numa_allocate_cpumask()  to  create
       it.   If the bitmask is not long enough errno will be set to ERANGE and
       -1 returned. On success 0 is returned.

       numa_node_of_cpu() returns the node that a cpu belongs to. If the  user
       supplies  an  invalid  cpu  errno  will be set to EINVAL and -1 will be
       returned.

       numa_allocate_cpumask () returns a bitmask of a size equal to the  ker-
       nel's  cpu  mask (kernel type cpumask_t).  In other words, large enough
       to represent NR_CPUS cpus.  This number of cpus can be gotten by  call-
       ing numa_num_possible_cpus().  The bitmask is zero-filled.

       numa_free_cpumask  frees  a  cpumask  previously allocate by numa_allo-
       cate_cpumask.

       numa_allocate_nodemask() returns a bitmask of a size equal to the  ker-
       nel's node mask (kernel type nodemask_t).  In other words, large enough
       to represent MAX_NUMNODES nodes.  This number of nodes can be gotten by
       calling numa_num_possible_nodes().  The bitmask is zero-filled.

       numa_free_nodemask()  frees a nodemask previous allocated by numa_allo-
       cate_nodemask().

       numa_bitmask_alloc() allocates a bitmask structure and  its  associated
       bit  mask.  The memory allocated for the bit mask contains enough words
       (type unsigned long) to contain n bits.  The bit mask  is  zero-filled.
       The bitmask structure points to the bit mask and contains the n value.

       numa_bitmask_clearall()  sets  all bits in the bit mask to 0.  The bit-
       mask structure points to the bit mask  and  contains  its  size  (  bmp
       ->size).   The  value  of  bmp is always returned.  Note that numa_bit-
       mask_alloc() creates a zero-filled bit mask.

       numa_bitmask_clearbit() sets a specified bit in a bit mask to 0.  Noth-
       ing is done if the n value is greater than the size of the bitmask (and
       no error is returned). The value of bmp is always returned.

       numa_bitmask_equal() returns 1 if two bitmasks are equal.  It returns 0
       if  they are not equal.  If the bitmask structures control bit masks of
       different sizes, the "missing" trailing bits of the  smaller  bit  mask
       are considered to be 0.

       numa_bitmask_free()  deallocates  the memory of both the bitmask struc-
       ture pointed to by bmp and the bit mask.  It is an error to attempt  to
       free this bitmask twice.

       numa_bitmask_isbitset()  returns  the value of a specified bit in a bit
       mask.  If the n value is greater than the size of the  bit  map,  0  is
       returned.

       numa_bitmask_nbytes()  returns the size (in bytes) of the bit mask con-
       trolled by bmp.  The bit masks are always  full  words  (type  unsigned
       long), and the returned size is the actual size of all those words.

       numa_bitmask_setall()  sets all bits in the bit mask to 1.  The bitmask
       structure points to the bit mask and contains its size (  bmp  ->size).
       The value of bmp is always returned.

       numa_bitmask_setbit() sets a specified bit in a bit mask to 1.  Nothing
       is done if n is greater than the size of the bitmask (and no  error  is
       returned). The value of bmp is always returned.

       copy_bitmask_to_nodemask()  copies the body (the bit map itself) of the
       bitmask structure pointed to by bmp to the nodemask_t structure pointed
       to  by  the nodemask pointer. If the two areas differ in size, the copy
       is truncated to the size of the receiving field or zero-filled.

       copy_nodemask_to_bitmask() copies the nodemask_t structure  pointed  to
       by the nodemask pointer to the body (the bit map itself) of the bitmask
       structure pointed to by the bmp pointer. If the  two  areas  differ  in
       size, the copy is truncated to the size of the receiving field or zero-
       filled.

       copy_bitmask_to_bitmask() copies the body (the bit map itself)  of  the
       bitmask  structure pointed to by the bmpfrom pointer to the body of the
       bitmask structure pointed to by the bmpto pointer.  If  the  two  areas
       differ  in  size,  the  copy  is truncated to the size of the receiving
       field or zero-filled.

       numa_bitmask_weight() returns a count of the bits that are set  in  the
       body of the bitmask pointed to by the bmp argument.

       numa_move_pages()  moves  a  list  of pages in the address space of the
       currently executing or current process.  It simply uses the  move_pages
       system call.
       pid - ID of task.  If not valid, use the current task.
       count - Number of pages.
       pages - List of pages to move.
       nodes - List of nodes to which pages can be moved.
       status - Field to which status is to be returned.
       flags - MPOL_MF_MOVE or MPOL_MF_MOVE_ALL
       See move_pages(2).

       numa_migrate_pages() simply uses the migrate_pages system call to cause
       the pages of the calling task, or a specified task, to be migated  from
       one set of nodes to another.  See migrate_pages(2).  The bit masks rep-
       resenting the nodes should be allocated with numa_allocate_nodemask() ,
       or   with   numa_bitmask_alloc()   using   an  n  value  returned  from
       numa_num_possible_nodes().  A task's current node set can be gotten  by
       calling  numa_get_membind().   Bits  in  the tonodes mask can be set by
       calls to numa_bitmask_setbit().

       numa_error() is a libnuma internal function that can be  overridden  by
       the  user program.  This function is called with a char * argument when
       a libnuma function fails.  Overriding the library  internal  definition
       makes it possible to specify a different error handling strategy when a
       libnuma function fails.  It  does  not  affect  numa_available().   The
       numa_error()  function defined in libnuma prints an error on stderr and
       terminates the program if  numa_exit_on_error  is  set  to  a  non-zero
       value.  The default value of numa_exit_on_error is zero.

       numa_warn()  is a libnuma internal function that can be also overridden
       by the user program.  It is called to warn  the  user  when  a  libnuma
       function  encounters  a  non-fatal  error.   The default implementation
       prints a warning to stderr.  The first  argument  is  a  unique  number
       identifying  each warning. After that there is a printf(3)-style format
       string and a variable number of arguments.  numa_warn exits the program
       when  numa_exit_on_warn  is set to a non-zero value.  The default value
       of numa_exit_on_warn is zero.

Compatibility with libnuma version 1
       Binaries that were compiled for libnuma version 1 need not  be  re-com-
       piled to run with libnuma version 2.
       Source  codes  written for libnuma version 1 may be re-compiled without
       change with version 2 installed. To do so, in the code's  Makefile  add
       this option to CFLAGS:  -DNUMA_VERSION1_COMPATIBILITY

THREAD SAFETY
       numa_set_bind_policy  and  numa_exit_on_error  are  process global. The
       other calls are thread safe.

COPYRIGHT
       Copyright 2002, 2004, 2007, 2008 Andi Kleen,  SuSE  Labs.   libnuma  is
       under the GNU Lesser General Public License, v2.1.

SEE ALSO
       get_mempolicy(2),  set_mempolicy(2), getpagesize(2), mbind(2), mmap(2),
       shmat(2),   numactl(8),    sched_getaffinity(2)    sched_setaffinity(2)
       move_pages(2) migrate_pages(2)

SuSE Labs                        December 2007                         NUMA(3)

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