From b2ca916ce392a9d4cea3489a3efb2b627b839eaf Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sun, 16 Feb 2020 12:00:48 -0800 Subject: ACPI: NUMA: Up-level "map to online node" functionality 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 Acked-by: Rafael J. Wysocki Reviewed-by: Ingo Molnar Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/158188324802.894464.13128795207831894206.stgit@dwillia2-desk3.amr.corp.intel.com --- mm/mempolicy.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'mm/mempolicy.c') diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 977c641f78cf..756d6e5bb59f 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -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; -- cgit v1.2.3