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x86-64, NUMA: Better explain numa_distance handling

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

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
This commit is contained in:
Tejun Heo 2011-03-02 11:32:47 +01:00
parent ce0033307f
commit eb8c1e2c83
2 changed files with 15 additions and 2 deletions
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11
arch/x86/mm/numa_64.c
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@ -392,11 +392,12 @@ void __init numa_reset_distance(void)
{ {
size_t size = numa_distance_cnt * numa_distance_cnt * sizeof(numa_distance[0]); 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) if (numa_distance_cnt)
memblock_x86_free_range(__pa(numa_distance), memblock_x86_free_range(__pa(numa_distance),
__pa(numa_distance) + size); __pa(numa_distance) + size);
numa_distance_cnt = 0; numa_distance_cnt = 0;
numa_distance = NULL; numa_distance = NULL; /* enable table creation */
} }
static int __init numa_alloc_distance(void) 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 * 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 * doesn't exist, one which is large enough to accomodate all the currently
* known nodes will be created. * 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) void __init numa_set_distance(int from, int to, int distance)
{ {

6
arch/x86/mm/numa_emulation.c
View File

@ -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) if (emu_nid_to_phys[i] == NUMA_NO_NODE)
emu_nid_to_phys[i] = 0; 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(); numa_reset_distance();
for (i = 0; i < MAX_NUMNODES; i++) { for (i = 0; i < MAX_NUMNODES; i++) {
for (j = 0; j < MAX_NUMNODES; j++) { for (j = 0; j < MAX_NUMNODES; j++) {