NAME
Configure Topology Detection -
Data Structures
struct hwloc_topology_discovery_support
Flags describing actual discovery support for this topology.
struct hwloc_topology_cpubind_support
Flags describing actual binding support for this topology.
struct hwloc_topology_support
Set of flags describing actual support for this topology.
Enumerations
enum hwloc_topology_flags_e { HWLOC_TOPOLOGY_FLAG_WHOLE_SYSTEM,
HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM }
Flags to be set onto a topology context before load.
Functions
HWLOC_DECLSPEC int hwloc_topology_ignore_type (hwloc_topology_t
topology, hwloc_obj_type_t type)
Ignore an object type.
HWLOC_DECLSPEC int hwloc_topology_ignore_type_keep_structure
(hwloc_topology_t topology, hwloc_obj_type_t type)
Ignore an object type if it does not bring any structure.
HWLOC_DECLSPEC int hwloc_topology_ignore_all_keep_structure
(hwloc_topology_t topology)
Ignore all objects that do not bring any structure.
HWLOC_DECLSPEC int hwloc_topology_set_flags (hwloc_topology_t topology,
unsigned long flags)
Set ORed flags to non-yet-loaded topology.
HWLOC_DECLSPEC int hwloc_topology_set_fsroot (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict
fsroot_path)
Change the file-system root path when building the topology from
sysfs/procfs.
HWLOC_DECLSPEC int hwloc_topology_set_pid (hwloc_topology_t
__hwloc_restrict topology, hwloc_pid_t pid)
Change which pid the topology is viewed from.
HWLOC_DECLSPEC int hwloc_topology_set_synthetic (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict
description)
Enable synthetic topology.
HWLOC_DECLSPEC int hwloc_topology_set_xml (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict xmlpath)
Enable XML-file based topology.
HWLOC_DECLSPEC struct hwloc_topology_support *
hwloc_topology_get_support (hwloc_topology_t __hwloc_restrict
topology)
Retrieve the topology support.
Detailed Description
These functions can optionally be called between hwloc_topology_init()
and hwloc_topology_load() to configure how the detection should be
performed, e.g. to ignore some objects types, define a synthetic
topology, etc.
If none of them is called, the default is to detect all the objects of
the machine that the caller is allowed to access.
This default behavior may also be modified through environment
variables if the application did not modify it already. Setting
HWLOC_XMLFILE in the environment enforces the discovery from a XML file
as if hwloc_topology_set_xml() had been called. HWLOC_FSROOT switches
to reading the topology from the specified Linux filesystem root as if
hwloc_topology_set_fsroot() had been called. Finally, HWLOC_THISSYSTEM
enforces the return value of hwloc_topology_is_thissystem().
Enumeration Type Documentation
enum hwloc_topology_flags_e
Flags to be set onto a topology context before load. Flags should be
given to hwloc_topology_set_flags().
Enumerator:
HWLOC_TOPOLOGY_FLAG_WHOLE_SYSTEM
Detect the whole system, ignore reservations and offline
settings. Gather all resources, even if some were disabled by
the administrator. For instance, ignore Linux Cpusets and gather
all processors and memory nodes, and ignore the fact that some
resources may be offline.
HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM
Assume that the selected backend provides the topology for the
system on which we are running. This forces
hwloc_topology_is_thissystem to return 1, i.e. makes hwloc
assume that the selected backend provides the topology for the
system on which we are running, even if it is not the OS-
specific backend but the XML backend for instance. This means
making the binding functions actually call the OS-specific
system calls and really do binding, while the XML backend would
otherwise provide empty hooks just returning success.
Setting the environment variable HWLOC_THISSYSTEM may also result in
the same behavior.
This can be used for efficiency reasons to first detect the topology
once, save it to an XML file, and quickly reload it later through the
XML backend, but still having binding functions actually do bind.
Function Documentation
HWLOC_DECLSPEC struct hwloc_topology_support* hwloc_topology_get_support
(hwloc_topology_t __hwloc_restrict topology) [read]
Retrieve the topology support.
HWLOC_DECLSPEC int hwloc_topology_ignore_all_keep_structure
(hwloc_topology_t topology)
Ignore all objects that do not bring any structure. Ignore all objects
that do not bring any structure: Each ignored object should have a
single children or be the only child of its parent.
HWLOC_DECLSPEC int hwloc_topology_ignore_type (hwloc_topology_t topology,
hwloc_obj_type_t type)
Ignore an object type. Ignore all objects from the given type. The
bottom-level type HWLOC_OBJ_PU may not be ignored. The top-level object
of the hierarchy will never be ignored, even if this function succeeds.
HWLOC_DECLSPEC int hwloc_topology_ignore_type_keep_structure
(hwloc_topology_t topology, hwloc_obj_type_t type)
Ignore an object type if it does not bring any structure. Ignore all
objects from the given type as long as they do not bring any structure:
Each ignored object should have a single children or be the only child
of its parent. The bottom-level type HWLOC_OBJ_PU may not be ignored.
HWLOC_DECLSPEC int hwloc_topology_set_flags (hwloc_topology_t topology,
unsigned long flags)
Set OR’ed flags to non-yet-loaded topology. Set a OR’ed set of
hwloc_topology_flags_e onto a topology that was not yet loaded.
HWLOC_DECLSPEC int hwloc_topology_set_fsroot (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict fsroot_path)
Change the file-system root path when building the topology from
sysfs/procfs. On Linux system, use sysfs and procfs files as if they
were mounted on the given fsroot_path instead of the main file-system
root. Setting the environment variable HWLOC_FSROOT may also result in
this behavior. Not using the main file-system root causes
hwloc_topology_is_thissystem() to return 0.
Note:
For conveniency, this backend provides empty binding hooks which
just return success. To have hwloc still actually call OS-specific
hooks, the HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM has to be set to
assert that the loaded file is really the underlying system.
HWLOC_DECLSPEC int hwloc_topology_set_pid (hwloc_topology_t
__hwloc_restrict topology, hwloc_pid_t pid)
Change which pid the topology is viewed from. On some systems,
processes may have different views of the machine, for instance the set
of allowed CPUs. By default, hwloc exposes the view from the current
process. Calling hwloc_topology_set_pid() permits to make it expose the
topology of the machine from the point of view of another process.
Note:
hwloc_pid_t is pid_t on unix platforms, and HANDLE on native
Windows platforms
The ENOSYS error is returned on platforms that does not support
this feature.
HWLOC_DECLSPEC int hwloc_topology_set_synthetic (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict description)
Enable synthetic topology. Gather topology information from the given
description which should be a comma separated string of numbers
describing the arity of each level. Each number may be prefixed with a
type and a colon to enforce the type of a level. If only some level
types are enforced, hwloc will try to choose the other types according
to usual topologies, but it may fail and you may have to specify more
level types manually.
Note:
For conveniency, this backend provides empty binding hooks which
just return success.
HWLOC_DECLSPEC int hwloc_topology_set_xml (hwloc_topology_t
__hwloc_restrict topology, const char *__hwloc_restrict xmlpath)
Enable XML-file based topology. Gather topology information the XML
file given at xmlpath. Setting the environment variable HWLOC_XMLFILE
may also result in this behavior. This file may have been generated
earlier with lstopo file.xml.
Note:
For conveniency, this backend provides empty binding hooks which
just return success. To have hwloc still actually call OS-specific
hooks, the HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM has to be set to
assert that the loaded file is really the underlying system.
Author
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