One object may contain a distance structure describing distances between all its descendants at a given relative depth. If the containing object is the root object of the topology, then the distances are available for all objects in the machine.

The distance may be a memory latency, as defined by the ACPI SLIT specification. If so, the latency pointer will not be NULL and the pointed array will contain non-zero values.

In the future, some other types of distances may be considered. In these cases, latency will be NULL.

Field Documentation

float* hwloc_distances_s::latency

Matrix of latencies between objects, stored as a one-dimension array. May be NULL if the distances considered here are not latencies. Values are normalized to get 1.0 as the minimal value in the matrix. Latency from i-th to j-th object is stored in slot i*nbobjs+j.

float hwloc_distances_s::latency_base

The multiplier that should be applied to latency matrix to retrieve the original OS-provided latencies. Usually 10 on Linux since ACPI SLIT uses 10 for local latency.

float hwloc_distances_s::latency_max

The maximal value in the latency matrix.

unsigned hwloc_distances_s::nbobjs

Number of objects considered in the matrix. It is the number of descendant objects at relative_depth below the containing object. It corresponds to the result of hwloc_get_nbobjs_inside_cpuset_by_depth.

unsigned hwloc_distances_s::relative_depth

Relative depth of the considered objects below the object containing this distance information.

Author

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