From patchwork Tue Oct 10 15:19:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 9996531 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AB050603B5 for ; Tue, 10 Oct 2017 15:20:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98E71285ED for ; Tue, 10 Oct 2017 15:20:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8636A2865F; Tue, 10 Oct 2017 15:20:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 350D8285ED for ; Tue, 10 Oct 2017 15:20:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932360AbdJJPUC (ORCPT ); Tue, 10 Oct 2017 11:20:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:48420 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932354AbdJJPTt (ORCPT ); Tue, 10 Oct 2017 11:19:49 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 1CBEAAD97; Tue, 10 Oct 2017 15:19:47 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 8B5A71E35A5; Tue, 10 Oct 2017 17:19:46 +0200 (CEST) From: Jan Kara To: Cc: Mel Gorman , "Kirill A. Shutemov" , , Jan Kara Subject: [PATCH 1/7] mm: Speedup cancel_dirty_page() for clean pages Date: Tue, 10 Oct 2017 17:19:31 +0200 Message-Id: <20171010151937.26984-2-jack@suse.cz> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20171010151937.26984-1-jack@suse.cz> References: <20171010151937.26984-1-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP cancel_dirty_page() does quite some work even for clean pages (fetching of mapping, locking of memcg, atomic bit op on page flags) so it accounts for ~2.5% of cost of truncation of a clean page. That is not much but still dumb for something we don't need at all. Check whether a page is actually dirty and avoid any work if not. Acked-by: Mel Gorman Signed-off-by: Jan Kara --- include/linux/mm.h | 8 +++++++- mm/page-writeback.c | 4 ++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 065d99deb847..d14a9bb2a3d7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1430,7 +1430,13 @@ void account_page_cleaned(struct page *page, struct address_space *mapping, struct bdi_writeback *wb); int set_page_dirty(struct page *page); int set_page_dirty_lock(struct page *page); -void cancel_dirty_page(struct page *page); +void __cancel_dirty_page(struct page *page); +static inline void cancel_dirty_page(struct page *page) +{ + /* Avoid atomic ops, locking, etc. when not actually needed. */ + if (PageDirty(page)) + __cancel_dirty_page(page); +} int clear_page_dirty_for_io(struct page *page); int get_cmdline(struct task_struct *task, char *buffer, int buflen); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0b9c5cbe8eba..c3bed3f5cd24 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2623,7 +2623,7 @@ EXPORT_SYMBOL(set_page_dirty_lock); * page without actually doing it through the VM. Can you say "ext3 is * horribly ugly"? Thought you could. */ -void cancel_dirty_page(struct page *page) +void __cancel_dirty_page(struct page *page) { struct address_space *mapping = page_mapping(page); @@ -2644,7 +2644,7 @@ void cancel_dirty_page(struct page *page) ClearPageDirty(page); } } -EXPORT_SYMBOL(cancel_dirty_page); +EXPORT_SYMBOL(__cancel_dirty_page); /* * Clear a page's dirty flag, while caring for dirty memory accounting.