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ACPI: NUMA: Up-level "map to online node" functionality

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The acpi_map_pxm_to_online_node() helper is used to find the closest
online node to a given proximity domain. This is used to map devices in
a proximity domain with no online memory or cpus to the closest online
node and populate a device's 'numa_node' property. The numa_node
property allows applications to be migrated "close" to a resource.

In preparation for providing a generic facility to optionally map an
address range to its closest online node, or the node the range would
represent were it to be onlined (target_node), up-level the core of
acpi_map_pxm_to_online_node() to a generic mm/numa helper.

Cc: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/158188324802.894464.13128795207831894206.stgit@dwillia2-desk3.amr.corp.intel.com
This commit is contained in:
Dan Williams
2020-02-16 12:00:48 -08:00
parent bb6d3fb354
commit b2ca916ce3
4 changed files with 61 additions and 42 deletions
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30
mm/mempolicy.c
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@@ -127,6 +127,36 @@ static struct mempolicy default_policy = {
static struct mempolicy preferred_node_policy[MAX_NUMNODES];
/**
* numa_map_to_online_node - Find closest online node
* @nid: Node id to start the search
*
* Lookup the next closest node by distance if @nid is not online.
*/
int numa_map_to_online_node(int node)
{
int min_node;
if (node == NUMA_NO_NODE)
node = 0;
min_node = node;
if (!node_online(node)) {
int min_dist = INT_MAX, dist, n;
for_each_online_node(n) {
dist = node_distance(node, n);
if (dist < min_dist) {
min_dist = dist;
min_node = n;
}
}
}
return min_node;
}
EXPORT_SYMBOL_GPL(numa_map_to_online_node);
struct mempolicy *get_task_policy(struct task_struct *p)
{
struct mempolicy *pol = p->mempolicy;