nloc - Queries the NUMA Topology or Resource Affinity
Domains (libnuma library)
radset_t radset );
Points to a structure that specifies the criteria for
selecting a set of resource Affinity Domains (RADs). This
structure contains the following elements: The type of
resource for which the set of "nearby" RADs is requested.
The resource descriptor for which the RAD set is
requested. 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. Flags that influence the selection of
RADs. See DESCRIPTION for details. Specifies a buffer to
contain the set of RADs in the caller's partition that
satisfy the criteria specified by numa_attr.
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: Represents the distance value for resources that
are directly connected to the specified resource. 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: When specified, only RADs that have
processes bound to them will be returned in radset. When
specified, only RADs that do not have processes bound to
them will be returned in radset.
Success. Failure. In this case, errno is set to indicate
If the nloc() function fails, it sets errno to one of the
following values for the reason specified: The numa_attr
argument (or its nattr_descr field) or the radset argument
point to an invalid address. 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. The process specified by rd_pid does not
exist. There are too many symbolic links in rd_pathname.
The rd_pathname length exceeds MAXPATHLEN, or a component
of rd_pathname exceeds MAXNAMELEN. The file named by
rd_pathname does not exist. A component of rd_pathname is
not a directory.
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