numa

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
       *nodemask); 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);
       void numa_node_to_cpu_update();
       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
       *nodemask)
       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
       bitmask *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),
       preferred 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.  Furthermore, 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
       policies 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_to_cpu_update(), 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 associated 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_possible_nodes() and subtracting 1.

       numa_num_possible_nodes() returns the size of kernel's node mask
       (kernel 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
       current 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_allocate_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_allocate_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/status, 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
       structure.  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 little 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
       leading ! 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
       current 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 current 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
       follow the policy.

       numa_bind() binds the current task and its children to the nodes
       specified 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
       nodemask 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
       currently 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),
       family 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)
       family of functions.  The memory must be freed with numa_free().  On
       errors NULL is returned.

       numa_alloc_interleaved() allocates size bytes of memory page
       interleaved 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
       memory 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
       policy.  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*
       functions.  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
       uninitialized. The memory policy (and node bindings) associated with
       the original memory area will be preserved in the resized area. For
       example, if the initial area was allocated with a call to
       numa_alloc_onnode(), 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 original 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
       constraints 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
       allocating 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
       probably 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
       bitmask 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_to_cpu_update() Mark cpus bitmask of all nodes stale, then
       get the latest bitmask by calling numa_node_to_cpus() This allows to
       update the libnuma state after a CPU hotplug event. The application is
       in charge of detecting CPU hotplug events.

       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
       kernel'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
       calling numa_num_possible_cpus().  The bitmask is zero-filled.

       numa_free_cpumask frees a cpumask previously allocate by
       numa_allocate_cpumask.

       numa_allocate_nodemask() returns a bitmask of a size equal to the
       kernel'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_allocate_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
       bitmask structure points to the bit mask and contains its size ( bmp
       ->size).  The value of bmp is always returned.  Note that
       numa_bitmask_alloc() creates a zero-filled bit mask.

       numa_bitmask_clearbit() sets a specified bit in a bit mask to 0.
       Nothing 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
       structure 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
       controlled 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
       representing 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-
       compiled 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)