Subject: [PATCH] hugetlb: vmstat events for huge page allocations

Allocating huge pages directly from the buddy allocator is not guaranteed to
succeed.  Success depends on several factors (such as the amount of physical
memory available and the level of fragmentation).  With the addition of
dynamic hugetlb pool resizing, allocations can occur much more frequently.
For these reasons it is desirable to keep track of huge page allocation
successes and failures.

Add two new vmstat entries to track huge page allocations that succeed and
fail.  The presence of the two entries is contingent upon CONFIG_HUGETLB_PAGE
being enabled.

[akpm@linux-foundation.org: reduced ifdeffery]
Signed-off-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Eric Munson <ebmunson@us.ibm.com>
Tested-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Andy Whitcroft <apw@shadowen.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 11 insertions, 0 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 93ea46a0fba4..8deae4eb9696 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -242,6 +242,11 @@ static int alloc_fresh_huge_page(void)
                 hugetlb_next_nid = next_nid;
         } while (!page && hugetlb_next_nid != start_nid);
 
+        if (ret)
+                count_vm_event(HTLB_BUDDY_PGALLOC);
+        else
+                count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
+
         return ret;
 }
 
@@ -302,9 +307,11 @@ static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
                  */
                 nr_huge_pages_node[nid]++;
                 surplus_huge_pages_node[nid]++;
+                __count_vm_event(HTLB_BUDDY_PGALLOC);
         } else {
                 nr_huge_pages--;
                 surplus_huge_pages--;
+                __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
         }
         spin_unlock(&hugetlb_lock);
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 879bcc0a1d4c..4c21670f8d91 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -645,6 +645,10 @@ static const char * const vmstat_text[] = {
         "allocstall",
 
         "pgrotated",
+#ifdef CONFIG_HUGETLB_PAGE
+        "htlb_buddy_alloc_success",
+        "htlb_buddy_alloc_fail",
+#endif
 #endif
 };