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virnuma: Introduce virNumaGetDistances
The API gets a NUMA node and find distances to other nodes. The distances are returned in an array. If an item X within the array equals to value of zero, then there's no such node as X. Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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@ -1652,6 +1652,7 @@ virNodeSuspendGetTargetMask;
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virDomainNumatuneMemModeTypeFromString;
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virDomainNumatuneMemModeTypeToString;
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virNumaGetAutoPlacementAdvice;
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virNumaGetDistances;
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virNumaGetMaxNode;
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virNumaGetNodeMemory;
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virNumaIsAvailable;
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@ -216,6 +216,61 @@ virNumaGetMaxNode(void)
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}
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/**
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* virNumaGetDistances:
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* @node: identifier of the requested NUMA node
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* @distances: array of distances to sibling nodes
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* @ndistances: size of @distances
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*
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* Get array of distances to sibling nodes from @node. If a
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* distances[x] equals to zero, the node x is not enabled or
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* doesn't exist. As a special case, if @node itself refers to
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* disabled or nonexistent NUMA node, then @distances and
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* @ndistances are set to NULL and zero respectively.
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*
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* The distances are a bit of magic. For a local node the value
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* is 10, for remote it's typically 20 meaning that time penalty
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* for accessing a remote node is two time bigger than when
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* accessing a local node.
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*
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* Returns 0 on success, -1 otherwise.
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*/
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int
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virNumaGetDistances(int node,
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int **distances,
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int *ndistances)
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{
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int ret = -1;
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int max_node;
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size_t i;
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if (!numa_bitmask_isbitset(numa_nodes_ptr, node)) {
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VIR_DEBUG("Node %d does not exist", node);
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*distances = NULL;
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*ndistances = 0;
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return 0;
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}
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if ((max_node = virNumaGetMaxNode()) < 0)
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goto cleanup;
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if (VIR_ALLOC_N(*distances, max_node) < 0)
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goto cleanup;
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*ndistances = max_node + 1;
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for (i = 0; i<= max_node; i++) {
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if (!numa_bitmask_isbitset(numa_nodes_ptr, i))
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continue;
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(*distances)[i] = numa_distance(node, i);
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}
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ret = 0;
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cleanup:
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return ret;
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}
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/**
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* virNumaGetNodeMemory:
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* @node: identifier of the requested NUMA node
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@ -58,6 +58,9 @@ int virNumaSetupMemoryPolicy(virNumaTuneDef numatune,
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bool virNumaIsAvailable(void);
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int virNumaGetMaxNode(void);
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int virNumaGetDistances(int node,
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int **distances,
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int *ndistances);
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int virNumaGetNodeMemory(int node,
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unsigned long long *memsize,
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unsigned long long *memfree);
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