Hardware Locality (hwloc): Object levels, depths and types

Hardware Locality (hwloc) 2.14.0rc1

Enumerations | Functions
Object levels, depths and types

## Enumerations
enum | hwloc_get_type_depth_e { HWLOC_TYPE_DEPTH_UNKNOWN , HWLOC_TYPE_DEPTH_MULTIPLE , HWLOC_TYPE_DEPTH_NUMANODE , HWLOC_TYPE_DEPTH_BRIDGE , HWLOC_TYPE_DEPTH_PCI_DEVICE , HWLOC_TYPE_DEPTH_OS_DEVICE , HWLOC_TYPE_DEPTH_MISC , HWLOC_TYPE_DEPTH_MEMCACHE }

## Functions
int | hwloc_topology_get_depth (hwloc_topology_t restrict topology)
int | hwloc_get_type_depth (hwloc_topology_t topology, hwloc_obj_type_t type)
int | hwloc_get_memory_parents_depth (hwloc_topology_t topology)
int | hwloc_get_type_or_below_depth (hwloc_topology_t topology, hwloc_obj_type_t type)
int | hwloc_get_type_or_above_depth (hwloc_topology_t topology, hwloc_obj_type_t type)
hwloc_obj_type_t | hwloc_get_depth_type (hwloc_topology_t topology, int depth)
unsigned | hwloc_get_nbobjs_by_depth (hwloc_topology_t topology, int depth)
int | hwloc_get_nbobjs_by_type (hwloc_topology_t topology, hwloc_obj_type_t type)
hwloc_obj_t | hwloc_get_root_obj (hwloc_topology_t topology)
hwloc_obj_t | hwloc_get_obj_by_depth (hwloc_topology_t topology, int depth, unsigned idx)
hwloc_obj_t | hwloc_get_obj_by_type (hwloc_topology_t topology, hwloc_obj_type_t type, unsigned idx)
hwloc_obj_t | hwloc_get_next_obj_by_depth (hwloc_topology_t topology, int depth, hwloc_obj_t prev)
hwloc_obj_t | hwloc_get_next_obj_by_type (hwloc_topology_t topology, hwloc_obj_type_t type, hwloc_obj_t prev)

## Detailed Description

Be sure to see the figure in Terms and Definitions that shows a complete topology tree, including depths, child/sibling/cousin relationships, and an example of an asymmetric topology where one package has fewer caches than its peers.

## Enumeration Type Documentation

## ◆ hwloc_get_type_depth_e

enum hwloc_get_type_depth_e

Enumerator
HWLOC_TYPE_DEPTH_UNKNOWN | No object of given type exists in the topology.
HWLOC_TYPE_DEPTH_MULTIPLE | Objects of given type exist at different depth in the topology (only for Groups).
HWLOC_TYPE_DEPTH_NUMANODE | Virtual depth for NUMA nodes.
HWLOC_TYPE_DEPTH_BRIDGE | Virtual depth for bridge object level.
HWLOC_TYPE_DEPTH_PCI_DEVICE | Virtual depth for PCI device object level.
HWLOC_TYPE_DEPTH_OS_DEVICE | Virtual depth for software device object level.
HWLOC_TYPE_DEPTH_MISC | Virtual depth for Misc object.
HWLOC_TYPE_DEPTH_MEMCACHE | Virtual depth for MemCache object.

## Function Documentation

## ◆ hwloc_get_depth_type()

hwloc_obj_type_t hwloc_get_depth_type | ( | hwloc_topology_t | topology,
|  | int | depth )

Returns the type of objects at depth `depth`.

`depth` should between 0 and hwloc_topology_get_depth()-1, or a virtual depth such as HWLOC_TYPE_DEPTH_NUMANODE.

Returns
  The type of objects at depth `depth`.
  (hwloc_obj_type_t)-1 if depth `depth` does not exist.

## ◆ hwloc_get_memory_parents_depth()

int hwloc_get_memory_parents_depth | ( | hwloc_topology_t | topology | ) |

Return the depth of parents where memory objects are attached.

Memory objects have virtual negative depths because they are not part of the main CPU-side hierarchy of objects. This depth should not be compared with other level depths.

If all Memory objects are attached to Normal parents at the same depth, this parent depth may be compared to other as usual, for instance for knowing whether NUMA nodes is attached above or below Packages.

Returns
  The depth of Normal parents of all memory children if all these parents have the same depth. For instance the depth of the Package level if all NUMA nodes are attached to Package objects.
  HWLOC_TYPE_DEPTH_MULTIPLE if Normal parents of all memory children do not have the same depth. For instance if some NUMA nodes are attached to Packages while others are attached to Groups.

## ◆ hwloc_get_nbobjs_by_depth()

unsigned hwloc_get_nbobjs_by_depth | ( | hwloc_topology_t | topology,
|  | int | depth )

Returns the width of level at depth `depth`.

Returns
  The number of objects at topology depth `depth`.
  0 if there are no objects at depth `depth`.

## ◆ hwloc_get_nbobjs_by_type()

int hwloc_get_nbobjs_by_type | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type )
| inline

Returns the width of level type `type`.

Returns
  The number of objects of type `type`.
  -1 if there are multiple levels with objects of that type, e.g. HWLOC_OBJ_GROUP.
  0 if there are no objects at depth `depth`.

## ◆ hwloc_get_next_obj_by_depth()

hwloc_obj_t hwloc_get_next_obj_by_depth | ( | hwloc_topology_t | topology,
|  | int | depth,
|  | hwloc_obj_t | prev )
| inline

Returns the next object at depth `depth`.

Returns
  The first object at depth `depth` if `prev` is `NULL`.
  The object after `prev` at depth `depth` if `prev` is not `NULL`.
  `NULL` if there is no such object.

## ◆ hwloc_get_next_obj_by_type()

hwloc_obj_t hwloc_get_next_obj_by_type | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type,
|  | hwloc_obj_t | prev )
| inline

Returns the next object of type `type`.

Returns
  The first object of type `type` if `prev` is `NULL`.
  The object after `prev` of type `type` if `prev` is not `NULL`.
  `NULL` if there is no such object.
  `NULL` if there are multiple levels with objects of that type (e.g. HWLOC_OBJ_GROUP), the caller may fallback to hwloc_get_obj_by_depth().

## ◆ hwloc_get_obj_by_depth()

hwloc_obj_t hwloc_get_obj_by_depth | ( | hwloc_topology_t | topology,
|  | int | depth,
|  | unsigned | idx )

Returns the topology object at logical index `idx` from depth `depth`.

Returns
  The object if it exists.
  `NULL` if there is no object with this index and depth.

## ◆ hwloc_get_obj_by_type()

hwloc_obj_t hwloc_get_obj_by_type | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type,
|  | unsigned | idx )
| inline

Returns the topology object at logical index `idx` with type `type`.

Returns
  The object if it exists.
  `NULL` if there is no object with this index and type.
  `NULL` if there are multiple levels with objects of that type (e.g. HWLOC_OBJ_GROUP), the caller may fallback to hwloc_get_obj_by_depth().

## ◆ hwloc_get_root_obj()

hwloc_obj_t hwloc_get_root_obj | ( | hwloc_topology_t | topology | ) |
| inline

Returns the top-object of the topology-tree.

Its type is HWLOC_OBJ_MACHINE.

This function cannot return `NULL`.

## ◆ hwloc_get_type_depth()

int hwloc_get_type_depth | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type )

Returns the depth of objects of type `type`.

Returns
  The depth of objects of type `type`.
  A negative virtual depth if a NUMA node, I/O or Misc object type is given. These objects are stored in special levels that are not CPU-related. This virtual depth may be passed to other hwloc functions such as hwloc_get_obj_by_depth() but it should not be considered as an actual depth by the application. In particular, it should not be compared with any other object depth or with the entire topology depth.
  HWLOC_TYPE_DEPTH_UNKNOWN if no object of this type is present on the underlying architecture, or if the OS doesn't provide this kind of information.
  HWLOC_TYPE_DEPTH_MULTIPLE if type HWLOC_OBJ_GROUP is given and multiple levels of Groups exist.

Note
  If the type is absent but a similar type is acceptable, see also hwloc_get_type_or_below_depth() and hwloc_get_type_or_above_depth().

See also
  hwloc_get_memory_parents_depth() for managing the depth of memory objects.
  hwloc_type_sscanf_as_depth() for returning the depth of objects whose type is given as a string.

## ◆ hwloc_get_type_or_above_depth()

int hwloc_get_type_or_above_depth | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type )
| inline

Returns the depth of objects of type `type` or above.

If no object of this type is present on the underlying architecture, the function returns the depth of the first "present" object typically containing `type`.

This function is only meaningful for normal object types. If a memory, I/O or Misc object type is given, the corresponding virtual depth is always returned (see hwloc_get_type_depth()).

May return HWLOC_TYPE_DEPTH_MULTIPLE for HWLOC_OBJ_GROUP just like hwloc_get_type_depth().

## ◆ hwloc_get_type_or_below_depth()

int hwloc_get_type_or_below_depth | ( | hwloc_topology_t | topology,
|  | hwloc_obj_type_t | type )
| inline

Returns the depth of objects of type `type` or below.

If no object of this type is present on the underlying architecture, the function returns the depth of the first "present" object typically found inside `type`.

This function is only meaningful for normal object types. If a memory, I/O or Misc object type is given, the corresponding virtual depth is always returned (see hwloc_get_type_depth()).

May return HWLOC_TYPE_DEPTH_MULTIPLE for HWLOC_OBJ_GROUP just like hwloc_get_type_depth().

## ◆ hwloc_topology_get_depth()

int hwloc_topology_get_depth | ( | hwloc_topology_t restrict | topology | ) |

Get the depth of the hierarchical tree of objects.

This is the depth of HWLOC_OBJ_PU objects plus one.

Returns
  the depth of the object tree.

Note
  NUMA nodes, I/O and Misc objects are ignored when computing the depth of the tree (they are placed on special levels).