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nloc(3)


NAME

  nloc - Queries the NUMA Topology or Resource Affinity Domains (libnuma
  library)


SYNOPSIS

  #include <numa.h>

  int nloc(
	  numa_attr_t *numa_attr,
	  radset_t radset );


PARAMETERS

  numa_attr
      Points to a structure that specifies the criteria for selecting a set
      of resource Affinity Domains (RADs). This structure contains the
      following elements:

      nattr_type
	  The type of resource for which the set of "nearby" RADs is
	  requested.

      nattr_descr
	  The resource descriptor for which the RAD set is requested.

      nattr_distance
	  The distance criteria for selecting resources. RADs in the caller's
	  partition that have a distance <= this value will be included in
	  the radset returned by nloc(). See DESCRIPTION for more information
	  about nattr_distance.

      nattr_flags
	  Flags that influence the selection of RADs. See DESCRIPTION for
	  details.

  radset
      Specifies a buffer to contain the set of RADs in the caller's partition
      that satisfy the criteria specified by numa_attr.


DESCRIPTION

  The nloc() function will return in radset the set of RADs that have a
  distance <= the nattr_distance value from the specified resource.  The
  returned radset value may be used as an argument to explicit process or
  thread placement APIs or in the mattr_radset member of a memory allocation
  policy structure for explicit memory placement.

  The following symbolic values for nattr_distance are defined:

  RAD_DIST_LOCAL
	  Represents the distance value for resources that are directly
	  connected to the specified resource.

  RAD_DIST_REMOTE
	  Represents the maximum distance value for the system.	 Generally,
	  all RADs in the partition will be <= this distance.

  For NUMA topologies in which RADs are variable distances from one another,
  RAD_DIST_LOCAL can be incremented to specify a specific distance.  In other
  words, RAD_DIST_LOCAL + 1 represents the distance to the closest RADs,
  RAD_DIST_LOCAL + 2 represents the distance to the next closest RADs, and so
  forth. For example, when nattr_distance is set to RAD_DIST_LOCAL + 2,
  nloc() returns in radset the set of RADs that have a distance <=
  (RAD_DIST_LOCAL + 2) from the specified resource. For NUMA topologies where
  all RADs are equidistant from one another, <= (RAD_DIST_LOCAL + n), where n
  is a positive integer, is equivalent to <= RAD_DIST_REMOTE.

  The following symbolic values are defined for the nattr_flags field:

  RAD_BOUND
	  When specified, only RADs that have processes bound to them will be
	  returned in radset.

  RAD_NOBOUND
	  When specified, only RADs that do not have processes bound to them
	  will be returned in radset.


RETURN VALUES

  0   Success.

  -1  Failure. In this case, errno is set to indicate the error.


ERRORS

  If the nloc() function fails, it sets errno to one of the following values
  for the reason specified:

  [EFAULT]
      The numa_attr argument (or its nattr_descr field) or the radset
      argument point to an invalid address.

  [EINVAL]
      One or more of the following conditions are true:

	·  The numa_attr argument contains an undefined type value.

	·  The nattr_descr field contains an invalid resource value for the
	   specified type.

	·  The nattr_distance or nattr_flags fields contain an invalid or
	   undefined value.

  [ESRCH]
      The process specified by rd_pid does not exist.

  [ELOOP]
      There are too many symbolic links in rd_pathname.

  [ENAMETOOLONG]
      The rd_pathname length exceeds MAXPATHLEN, or a component of
      rd_pathname exceeds MAXNAMELEN.

  [ENOENT]
      The file named by rd_pathname does not exist.

  [ENOTDIR]
      A component of rd_pathname is not a directory.


SEE ALSO

  Functions: rad_get_info(3)

  Files: numa_types(4)

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