diff options
Diffstat (limited to 'include/linux/topology.h')
| -rw-r--r-- | include/linux/topology.h | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/include/linux/topology.h b/include/linux/topology.h index 52f5850730b3..24e715f0f6d2 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -240,6 +240,29 @@ static inline const struct cpumask *cpu_smt_mask(int cpu) } #endif +#ifndef topology_is_primary_thread + +static inline bool topology_is_primary_thread(unsigned int cpu) +{ + /* + * When disabling SMT, the primary thread of the SMT will remain + * enabled/active. Architectures that have a special primary thread + * (e.g. x86) need to override this function. Otherwise the first + * thread in the SMT can be made the primary thread. + * + * The sibling cpumask of an offline CPU always contains the CPU + * itself on architectures using the implementation of + * CONFIG_GENERIC_ARCH_TOPOLOGY for building their topology. + * Other architectures not using CONFIG_GENERIC_ARCH_TOPOLOGY for + * building their topology have to check whether to use this default + * implementation or to override it. + */ + return cpu == cpumask_first(topology_sibling_cpumask(cpu)); +} +#define topology_is_primary_thread topology_is_primary_thread + +#endif + static inline const struct cpumask *cpu_cpu_mask(int cpu) { return cpumask_of_node(cpu_to_node(cpu)); @@ -262,6 +285,36 @@ sched_numa_hop_mask(unsigned int node, unsigned int hops) #endif /* CONFIG_NUMA */ /** + * for_each_node_numadist() - iterate over nodes in increasing distance + * order, starting from a given node + * @node: the iteration variable and the starting node. + * @unvisited: a nodemask to keep track of the unvisited nodes. + * + * This macro iterates over NUMA node IDs in increasing distance from the + * starting @node and yields MAX_NUMNODES when all the nodes have been + * visited. + * + * Note that by the time the loop completes, the @unvisited nodemask will + * be fully cleared, unless the loop exits early. + * + * The difference between for_each_node() and for_each_node_numadist() is + * that the former allows to iterate over nodes in numerical order, whereas + * the latter iterates over nodes in increasing order of distance. + * + * This complexity of this iterator is O(N^2), where N represents the + * number of nodes, as each iteration involves scanning all nodes to + * find the one with the shortest distance. + * + * Requires rcu_lock to be held. + */ +#define for_each_node_numadist(node, unvisited) \ + for (int __start = (node), \ + (node) = nearest_node_nodemask((__start), &(unvisited)); \ + (node) < MAX_NUMNODES; \ + node_clear((node), (unvisited)), \ + (node) = nearest_node_nodemask((__start), &(unvisited))) + +/** * for_each_numa_hop_mask - iterate over cpumasks of increasing NUMA distance * from a given node. * @mask: the iteration variable. |