From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f172.google.com (mail-pf0-f172.google.com [209.85.192.172]) by kanga.kvack.org (Postfix) with ESMTP id 662576B007E for ; Fri, 25 Mar 2016 19:45:57 -0400 (EDT) Received: by mail-pf0-f172.google.com with SMTP id 4so92117945pfd.0 for ; Fri, 25 Mar 2016 16:45:57 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id y8si9831708pas.240.2016.03.25.16.45.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Mar 2016 16:45:56 -0700 (PDT) From: Mike Kravetz Subject: [PATCH] mm/hugetlb: optimize minimum size (min_size) accounting Date: Fri, 25 Mar 2016 16:44:58 -0700 Message-Id: <1458949498-18916-1-git-send-email-mike.kravetz@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Naoya Horiguchi , Hillf Danton , David Rientjes , Dave Hansen , "Kirill A. Shutemov" , Andrew Morton , Paul Gortmaker , Mike Kravetz 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 --- mm/hugetlb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 06058ea..b9bfcf1 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 -- 2.4.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org