hwlocality_levels(3)

📦
version 2.15.0 · 13 versions
, in arch rolling

🌸 NAME 🌸

okay so bestie, this is hwlocality_levels(3) from the Library Functions Manual, and the official NAME line is hwlocality_levels - Object levels, depths and types. No cap, if you're trying to figure out where an object sits in the topology tree, this is your girl. 💅

✨ SYNOPSIS ✨

Enumerations

this enum is the whole vibe:

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

all the functions, served fresh:

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 🦋

bestie, do not skip the figure in Terms and Definitions — it 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. It's giving “look at the whole family tree”. 👑

🎀 Enumeration Type Documentation 🎀

enum hwloc_get_type_depth_e

the cast of characters (aka the enumerators):

  • 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 be 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).

🌈 Author 🌈

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