/**
* virNumaGetDistances:
* @node: identifier of the requested NUMA node
* @distances: array of distances to sibling nodes
* @ndistances: size of @distances
*
* Get array of distances to sibling nodes from @node. If a
* distances[x] equals to zero, the node x is not enabled or
* doesn't exist. As a special case, if @node itself refers to
* disabled or nonexistent NUMA node, then @distances and
* @ndistances are set to NULL and zero respectively.
*
* The distances are a bit of magic. For a local node the value
* is 10, for remote it's typically 20 meaning that time penalty
* for accessing a remote node is two time bigger than when
* accessing a local node.
*
* Returns 0 on success, -1 otherwise.
*/
int
virNumaGetDistances(int node,
int **distances,
int *ndistances)
{
int ret = -1;
int max_node;
size_t i;
if (!virNumaNodeIsAvailable(node)) {
VIR_DEBUG("Node %d does not exist", node);
*distances = NULL;
*ndistances = 0;
return 0;
}
if ((max_node = virNumaGetMaxNode()) < 0)
goto cleanup;
if (VIR_ALLOC_N(*distances, max_node + 1) < 0)
goto cleanup;
*ndistances = max_node + 1;
for (i = 0; i <= max_node; i++) {
if (!virNumaNodeIsAvailable(node))
continue;
(*distances)[i] = numa_distance(node, i);
}
ret = 0;
cleanup:
return ret;
}
bool
virNumaNodeIsAvailable(int node)
{
int max_node = virNumaGetMaxNode();
if (max_node < 0)
return false;
/* Do we have anything better? */
return (node >= 0) && (node <= max_node);
}
/*
* In case libvirt is compiled with full NUMA support, we need to mock
* this function in order to fake what numa nodes are available.
*/
bool
virNumaNodeIsAvailable(int node)
{
return node >= 0 && node <= virNumaGetMaxNode();
}
