From 09a95e29cb30a3930db22d340ddd072a82b6b0db Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Thu, 19 May 2016 17:11:01 -0700 Subject: mm/hugetlb: optimize minimum size (min_size) accounting It was observed that minimum size accounting associated with the hugetlbfs min_size mount option may not perform optimally and as expected. As huge pages/reservations are released from the filesystem and given back to the global pools, they are reserved for subsequent filesystem use as long as the subpool reserved count is less than subpool minimum size. It does not take into account used pages within the filesystem. The filesystem size limits are not exceeded and this is technically not a bug. However, better behavior would be to wait for the number of used pages/reservations associated with the filesystem to drop below the minimum size before taking reservations to satisfy minimum size. An optimization is also made to the hugepage_subpool_get_pages() routine which is called when pages/reservations are allocated. This does not change behavior, but simply avoids the accounting if all reservations have already been taken (subpool reserved count == 0). Signed-off-by: Mike Kravetz Acked-by: Naoya Horiguchi Cc: Hillf Danton Cc: David Rientjes Cc: Dave Hansen Cc: "Kirill A. Shutemov" Cc: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 5856093f9062..fb37ef810655 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -144,7 +144,8 @@ static long hugepage_subpool_get_pages(struct hugepage_subpool *spool, } } - if (spool->min_hpages != -1) { /* minimum size accounting */ + /* minimum size accounting */ + if (spool->min_hpages != -1 && spool->rsv_hpages) { if (delta > spool->rsv_hpages) { /* * Asking for more reserves than those already taken on @@ -182,7 +183,8 @@ static long hugepage_subpool_put_pages(struct hugepage_subpool *spool, if (spool->max_hpages != -1) /* maximum size accounting */ spool->used_hpages -= delta; - if (spool->min_hpages != -1) { /* minimum size accounting */ + /* minimum size accounting */ + if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) { if (spool->rsv_hpages + delta <= spool->min_hpages) ret = 0; else -- cgit