From patchwork Mon Sep 9 03:25:17 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Yan, Zheng" X-Patchwork-Id: 273478 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 5FFE52C00D1 for ; Mon, 9 Sep 2013 13:25:43 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752279Ab3IIDZm (ORCPT ); Sun, 8 Sep 2013 23:25:42 -0400 Received: from mga03.intel.com ([143.182.124.21]:18139 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751765Ab3IIDZl (ORCPT ); Sun, 8 Sep 2013 23:25:41 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by azsmga101.ch.intel.com with ESMTP; 08 Sep 2013 20:25:25 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,866,1371106800"; d="scan'208";a="392845911" Received: from zyan5-mobl.sh.intel.com ([10.239.13.115]) by fmsmga001.fm.intel.com with ESMTP; 08 Sep 2013 20:25:24 -0700 From: "Yan, Zheng" To: linux-ext4@vger.kernel.org Cc: jack@suse.cz, tytso@mit.edu, lkp@linux.intel.com, "Yan, Zheng" Subject: [PATCH] ext4: fix delayed pages writback regression. Date: Mon, 9 Sep 2013 11:25:17 +0800 Message-Id: <1378697117-5894-1-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.8.1.4 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: "Yan, Zheng" Our Linux Kernel Performance project found that commit 4e7ea81db5 (ext4: restructure writeback path) indroduced a read performance regression. After the commit, ext4 does not merge adjacent delayed pages during writeback. The regression is caused by the "buffer mapped" check in mpage_add_bh_to_extent(), delayed dirty pages are not mapped. Signed-off-by: Yan, Zheng --- fs/ext4/inode.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c79fd7d..f2034cb 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1944,8 +1944,9 @@ static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk, struct ext4_map_blocks *map = &mpd->map; /* Buffer that doesn't need mapping for writeback? */ - if (!buffer_dirty(bh) || !buffer_mapped(bh) || - (!buffer_delay(bh) && !buffer_unwritten(bh))) { + if (!buffer_dirty(bh) || + (!buffer_mapped(bh) && + !buffer_delay(bh) && !buffer_unwritten(bh))) { /* So far no extent to map => we write the buffer right away */ if (map->m_len == 0) return true;