Commit 16d79f2a authored by Andrea Righi's avatar Andrea Righi Committed by Tejun Heo
Browse files

mm/numa: Introduce nearest_node_nodemask() 



Introduce the new helper nearest_node_nodemask() to find the closest
node in a specified nodemask from a given starting node.

Returns MAX_NUMNODES if no node is found.

Suggested-by: default avatarYury Norov [NVIDIA] <yury.norov@gmail.com>
Signed-off-by: default avatarAndrea Righi <arighi@nvidia.com>
Acked-by: default avatarYury Norov [NVIDIA] <yury.norov@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 14a8262f

include/linux/numa.h

+7 −0
Original line number Diff line number Diff line
@@ -31,6 +31,8 @@ void __init alloc_offline_node_data(int nid); 
/* Generic implementation available */

int numa_nearest_node(int node, unsigned int state);



int nearest_node_nodemask(int node, nodemask_t *mask);



#ifndef memory_add_physaddr_to_nid

int memory_add_physaddr_to_nid(u64 start);

#endif
@@ -47,6 +49,11 @@ static inline int numa_nearest_node(int node, unsigned int state) 
	return NUMA_NO_NODE;

}



static inline int nearest_node_nodemask(int node, nodemask_t *mask)

{

	return NUMA_NO_NODE;

}



static inline int memory_add_physaddr_to_nid(u64 start)

{

	return 0;

mm/mempolicy.c

+31 −0
Original line number Diff line number Diff line
@@ -196,6 +196,37 @@ int numa_nearest_node(int node, unsigned int state) 
}

EXPORT_SYMBOL_GPL(numa_nearest_node);



/**

 * nearest_node_nodemask - Find the node in @mask at the nearest distance

 *			   from @node.

 *

 * @node: a valid node ID to start the search from.

 * @mask: a pointer to a nodemask representing the allowed nodes.

 *

 * This function iterates over all nodes in @mask and calculates the

 * distance from the starting @node, then it returns the node ID that is

 * the closest to @node, or MAX_NUMNODES if no node is found.

 *

 * Note that @node must be a valid node ID usable with node_distance(),

 * providing an invalid node ID (e.g., NUMA_NO_NODE) may result in crashes

 * or unexpected behavior.

 */

int nearest_node_nodemask(int node, nodemask_t *mask)

{

	int dist, n, min_dist = INT_MAX, min_node = MAX_NUMNODES;



	for_each_node_mask(n, *mask) {

		dist = node_distance(node, n);

		if (dist < min_dist) {

			min_dist = dist;

			min_node = n;

		}

	}



	return min_node;

}

EXPORT_SYMBOL_GPL(nearest_node_nodemask);



struct mempolicy *get_task_policy(struct task_struct *p)

{

	struct mempolicy *pol = p->mempolicy;