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Commit eb8c1e2c authored by Tejun Heo's avatar Tejun Heo
Browse files

x86-64, NUMA: Better explain numa_distance handling 



Handling of out-of-bounds distances and allocation failure can use
better documentation.  Add it.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
parent ce003330

arch/x86/mm/numa_64.c

+10 −1
Original line number Diff line number Diff line
@@ -392,11 +392,12 @@ void __init numa_reset_distance(void) 
{

	size_t size = numa_distance_cnt * numa_distance_cnt * sizeof(numa_distance[0]);



	/* numa_distance could be 1LU marking allocation failure, test cnt */

	if (numa_distance_cnt)

		memblock_x86_free_range(__pa(numa_distance),

					__pa(numa_distance) + size);

	numa_distance_cnt = 0;

	numa_distance = NULL;

	numa_distance = NULL;	/* enable table creation */

}



static int __init numa_alloc_distance(void)
@@ -447,6 +448,14 @@ static int __init numa_alloc_distance(void) 
 * Set the distance from node @from to @to to @distance.  If distance table

 * doesn't exist, one which is large enough to accomodate all the currently

 * known nodes will be created.

 *

 * If such table cannot be allocated, a warning is printed and further

 * calls are ignored until the distance table is reset with

 * numa_reset_distance().

 *

 * If @from or @to is higher than the highest known node at the time of

 * table creation or @distance doesn't make sense, the call is ignored.

 * This is to allow simplification of specific NUMA config implementations.

 */

void __init numa_set_distance(int from, int to, int distance)

{

arch/x86/mm/numa_emulation.c

+5 −1
Original line number Diff line number Diff line
@@ -379,7 +379,11 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) 
		if (emu_nid_to_phys[i] == NUMA_NO_NODE)

			emu_nid_to_phys[i] = 0;



	/* transform distance table */

	/*

	 * Transform distance table.  numa_set_distance() ignores all

	 * out-of-bound distances.  Just call it for every possible node

	 * combination.

	 */

	numa_reset_distance();

	for (i = 0; i < MAX_NUMNODES; i++) {

		for (j = 0; j < MAX_NUMNODES; j++) {