From patchwork Fri Aug 14 04:34:40 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 7012241 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 0EE7DC05AC for ; Fri, 14 Aug 2015 05:16:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 42266207D4 for ; Fri, 14 Aug 2015 05:16:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50483207D2 for ; Fri, 14 Aug 2015 05:16:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752436AbbHNFQI (ORCPT ); Fri, 14 Aug 2015 01:16:08 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:33419 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751949AbbHNFQG (ORCPT ); Fri, 14 Aug 2015 01:16:06 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out02.mta.xmission.com with esmtps (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZQ6o7-0005xc-BI; Thu, 13 Aug 2015 22:41:31 -0600 Received: from 67-3-205-173.omah.qwest.net ([67.3.205.173] helo=x220.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1ZQ6o5-0007J7-Ll; Thu, 13 Aug 2015 22:41:31 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linux Containers Cc: linux-fsdevel@vger.kernel.org, Al Viro , Andy Lutomirski , "Serge E. Hallyn" , Richard Weinberger , Andrey Vagin , Jann Horn , Willy Tarreau , Omar Sandoval , Miklos Szeredi , Linus Torvalds , "J. Bruce Fields" References: <871tncuaf6.fsf@x220.int.ebiederm.org> <87mw5xq7lt.fsf@x220.int.ebiederm.org> <87a8yqou41.fsf_-_@x220.int.ebiederm.org> <874moq9oyb.fsf_-_@x220.int.ebiederm.org> <871tfkawu9.fsf_-_@x220.int.ebiederm.org> <87egjk9i61.fsf_-_@x220.int.ebiederm.org> <20150810043637.GC14139@ZenIV.linux.org.uk> <877foymrwt.fsf@x220.int.ebiederm.org> <87wpwyjxwc.fsf_-_@x220.int.ebiederm.org> Date: Thu, 13 Aug 2015 23:34:40 -0500 In-Reply-To: <87wpwyjxwc.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Thu, 13 Aug 2015 23:29:23 -0500") Message-ID: <87y4heij33.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 X-XM-AID: U2FsdGVkX19fZFSk1aS4JLW4X+iBbYZwZAukZNOB/Z0= X-SA-Exim-Connect-IP: 67.3.205.173 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00,LOTS_OF_MONEY, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *;Linux Containers X-Spam-Relay-Country: X-Spam-Timing: total 1255 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 4.4 (0.4%), b_tie_ro: 3.2 (0.3%), parse: 1.07 (0.1%), extract_message_metadata: 14 (1.1%), get_uri_detail_list: 1.65 (0.1%), tests_pri_-1000: 6 (0.5%), tests_pri_-950: 1.34 (0.1%), tests_pri_-900: 1.17 (0.1%), tests_pri_-400: 24 (1.9%), check_bayes: 23 (1.8%), b_tokenize: 6 (0.5%), b_tok_get_all: 7 (0.6%), b_comp_prob: 2.5 (0.2%), b_tok_touch_all: 4.3 (0.3%), b_finish: 0.88 (0.1%), tests_pri_0: 1193 (95.1%), tests_pri_500: 6 (0.5%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH review 6/8] dcache: Only read d_flags once is d_is_dir X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) 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 Cache the value of __d_entry_type in d_is_dir and test if it equal to DCACHE_DIRECTORY_TYPE or DCACHE_AUTODIR_TYPE. The generated assembly goes from: movl (%rdi), %eax # MEM[(volatile __u32 *)dentry_3(D)], tmp73 andl $7340032, %eax #, tmp73 cmpl $2097152, %eax #, tmp73 je .L1091 #, movl (%rdi), %eax # MEM[(volatile __u32 *)dentry_3(D)], tmp74 andl $7340032, %eax #, tmp74 cmpl $3145728, %eax #, tmp74 je .L1091 #, to: movl (%rdi), %eax # MEM[(volatile __u32 *)dentry_3(D)], tmp71 andl $6291456, %eax #, tmp71 cmpl $2097152, %eax #, tmp71 jne .L1091 #, Which with only one read of d_flags, one comparison and one jump is dramatically better code. As __d_entry_type is not written to allow the compiler to optimize away anything that it does, when it is possible and reasonable to optimize things away the optimization needs to be performend manually. Signed-off-by: "Eric W. Biederman" --- include/linux/dcache.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 5b69856b45a2..82eb50aaf446 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -443,7 +443,8 @@ static inline bool d_is_autodir(const struct dentry *dentry) static inline bool d_is_dir(const struct dentry *dentry) { - return d_can_lookup(dentry) || d_is_autodir(dentry); + unsigned type = __d_entry_type(dentry); + return (type == DCACHE_DIRECTORY_TYPE) || (type == DCACHE_AUTODIR_TYPE); } static inline bool d_is_symlink(const struct dentry *dentry)