From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id F0CEA6B03AD for ; Wed, 19 Apr 2017 03:06:50 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id g23so8162237pfj.10 for ; Wed, 19 Apr 2017 00:06:50 -0700 (PDT) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id a101si1528678pli.74.2017.04.19.00.06.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Apr 2017 00:06:50 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm -v9 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map Date: Wed, 19 Apr 2017 15:06:25 +0800 Message-Id: <20170419070625.19776-4-ying.huang@intel.com> In-Reply-To: <20170419070625.19776-1-ying.huang@intel.com> References: <20170419070625.19776-1-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Johannes Weiner From: Huang Ying If there is no compound map for a THP (Transparent Huge Page), it is possible that the map count of some sub-pages of the THP is 0. So it is better to split the THP before swapping out. In this way, the sub-pages not mapped will be freed, and we can avoid the unnecessary swap out operations for these sub-pages. Cc: Johannes Weiner Signed-off-by: "Huang, Ying" --- mm/swap_state.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 3a3217f68937..b025c9878e5e 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -192,9 +192,15 @@ int add_to_swap(struct page *page, struct list_head *list) VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageUptodate(page), page); - /* cannot split, skip it */ - if (unlikely(PageTransHuge(page)) && !can_split_huge_page(page, NULL)) - return 0; + if (unlikely(PageTransHuge(page))) { + /* cannot split, skip it */ + if (!can_split_huge_page(page, NULL)) + return 0; + /* fallback to split huge page firstly if no PMD map */ + if (!compound_mapcount(page) && + split_huge_page_to_list(page, list)) + return 0; + } retry: entry = get_swap_page(page); -- 2.11.0 -- 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