From: Ted Ts'o Subject: Re: [PATCH 2/2] ext4: avoid finding next leaf if newext->ee_block smaller than fex->ee_block Date: Mon, 11 Jul 2011 15:52:11 -0400 Message-ID: <20110711195211.GQ28763@thunk.org> References: <1309421014-6148-1-git-send-email-sanbai@taobao.com> <1309421014-6148-2-git-send-email-sanbai@taobao.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Robin Dong , linux-ext4@vger.kernel.org, Robin Dong To: Yongqiang Yang Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:45194 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757419Ab1GKTwP (ORCPT ); Mon, 11 Jul 2011 15:52:15 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Jun 30, 2011 at 04:42:31PM +0800, Yongqiang Yang wrote: > How about: > next = EXT_MAX_BLOCKS; > if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block) > next = ext4_ext_next_leaf_block(inode, path); > if (next != EXT_MAX_BLOCKS) { Agreed, that's a better way of doing things. Also, Robin, please compare and contrast your description with mine. The commit description shouldn't just be a textual description of the change. It should give the larger context of the change and why it's important. - Ted commit 2a3f7e0e0e55f8817fbe92d111ef2a06e6b8ef18 Author: Robin Dong Date: Mon Jul 11 15:43:38 2011 -0400 ext4: avoid unneeded ext4_ext_next_leaf_block() while inserting extents Optimize ext4_exT_insert_extent() by avoiding ext4_ext_next_leaf_block() when the result is not used/needed. Signed-off-by: Robin Dong Signed-off-by: "Theodore Ts'o" diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 9cbdcb2..f1c538e 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1730,9 +1730,10 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode, /* probably next leaf has space for us? */ fex = EXT_LAST_EXTENT(eh); - next = ext4_ext_next_leaf_block(inode, path); - if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block) - && next != EXT_MAX_BLOCKS) { + next = EXT_MAX_BLOCKS; + if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)) + next = ext4_ext_next_leaf_block(inode, path); + if (next != EXT_MAX_BLOCKS) { ext_debug("next leaf block - %d\n", next); BUG_ON(npath != NULL); npath = ext4_ext_find_extent(inode, next, NULL);