On 06/13/2017 11:00 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> alloc_huge_page_nodemask tries to allocate from any numa node in the
> allowed node mask starting from lower numa nodes. This might lead to
> filling up those low NUMA nodes while others are not used. We can reduce
> this risk by introducing a concept of the preferred node similar to what
> we have in the regular page allocator. We will start allocating from the
> preferred nid and then iterate over all allowed nodes in the zonelist
> order until we try them all.
>
> This is mimicking the page allocator logic except it operates on
> per-node mempools. dequeue_huge_page_vma already does this so distill
> the zonelist logic into a more generic dequeue_huge_page_nodemask
> and use it in alloc_huge_page_nodemask.
>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
I've reviewed the current version in git, where patch 3/4 is folded.
Noticed some things below, but after fixing:
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -897,29 +897,58 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
> return page;
> }
>
> -static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
> +/* Movability of hugepages depends on migration support. */
> +static inline gfp_t htlb_alloc_mask(struct hstate *h)
> {
> - struct page *page;
> - int node;
> + if (hugepages_treat_as_movable || hugepage_migration_supported(h))
> + return GFP_HIGHUSER_MOVABLE;
> + else
> + return GFP_HIGHUSER;
> +}
>
> - if (nid != NUMA_NO_NODE)
> - return dequeue_huge_page_node_exact(h, nid);
> +static struct page *dequeue_huge_page_nodemask(struct hstate *h, int nid,
> + nodemask_t *nmask)
> +{
> + unsigned int cpuset_mems_cookie;
> + struct zonelist *zonelist;
> + struct page *page = NULL;
> + struct zone *zone;
> + struct zoneref *z;
> + gfp_t gfp_mask;
> + int node = -1;
> +
> + gfp_mask = htlb_alloc_mask(h);
> + zonelist = node_zonelist(nid, gfp_mask);
> +
> +retry_cpuset:
> + cpuset_mems_cookie = read_mems_allowed_begin();
> + for_each_zone_zonelist_nodemask(zone, z, zonelist, gfp_zone(gfp_mask), nmask) {
> + if (!cpuset_zone_allowed(zone, gfp_mask))
> + continue;
> + /*
> + * no need to ask again on the same node. Pool is node rather than
> + * zone aware
> + */
> + if (zone_to_nid(zone) == node)
> + continue;
> + node = zone_to_nid(zone);
>
> - for_each_online_node(node) {
> page = dequeue_huge_page_node_exact(h, node);
> if (page)
> - return page;
> + break;
Either keep return page here...
> }
> + if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
> + goto retry_cpuset;
> +
> return NULL;
... or return page here.
> }
>
> -/* Movability of hugepages depends on migration support. */
> -static inline gfp_t htlb_alloc_mask(struct hstate *h)
> +static struct page *dequeue_huge_page_node(struct hstate *h, int nid)
> {
> - if (hugepages_treat_as_movable || hugepage_migration_supported(h))
> - return GFP_HIGHUSER_MOVABLE;
> - else
> - return GFP_HIGHUSER;
> + if (nid != NUMA_NO_NODE)
> + return dequeue_huge_page_node_exact(h, nid);
> +
> + return dequeue_huge_page_nodemask(h, nid, NULL);
> }
>
...
> @@ -1655,25 +1661,25 @@ struct page *alloc_huge_page_node(struct hstate *h, int nid)
> return page;
> }
>
> -struct page *alloc_huge_page_nodemask(struct hstate *h, nodemask_t *nmask)
> +
> +struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
> + nodemask_t *nmask)
> {
> struct page *page = NULL;
> - int node;
>
> spin_lock(&hugetlb_lock);
> if (h->free_huge_pages - h->resv_huge_pages > 0) {
> - for_each_node_mask(node, *nmask) {
> - page = dequeue_huge_page_node_exact(h, node);
> - if (page)
> - break;
> - }
> + page = dequeue_huge_page_nodemask(h, preferred_nid, nmask);
> + if (page)
> + goto unlock;
> }
> +unlock:
This doesn't seem needed?
> spin_unlock(&hugetlb_lock);
> if (page)
> return page;
>
> /* No reservations, try to overcommit */
> - return __alloc_buddy_huge_page(h, NUMA_NO_NODE, nmask);
> + return __alloc_buddy_huge_page(h, preferred_nid, nmask);
> }
>
> /*
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
