From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 8473F6B03E8 for ; Thu, 6 Apr 2017 01:35:53 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id p20so25929774pgd.21 for ; Wed, 05 Apr 2017 22:35:53 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id d76si681437pfe.306.2017.04.05.22.35.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Apr 2017 22:35:52 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm -v8 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map Date: Thu, 6 Apr 2017 13:35:15 +0800 Message-Id: <20170406053515.4842-4-ying.huang@intel.com> In-Reply-To: <20170406053515.4842-1-ying.huang@intel.com> References: <20170406053515.4842-1-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 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 612fb2418df6..528af29327c9 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -205,7 +205,9 @@ int add_to_swap(struct page *page, struct list_head *list) /* cannot split, skip it */ if (!can_split_huge_page(page, NULL)) return 0; - huge = true; + /* fallback to split huge page firstly if no PMD map */ + if (compound_mapcount(page)) + huge = true; } #endif -- 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