From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753275AbaBXXoA (ORCPT ); Mon, 24 Feb 2014 18:44:00 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:50501 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752995AbaBXXnz (ORCPT ); Mon, 24 Feb 2014 18:43:55 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Stephen Rothwell Cc: Linus Torvalds , Miklos Szeredi , Al Viro , "Serge E. Hallyn" , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski , Rob Landley , Christoph Hellwig , Karel Zak , "J. Bruce Fields" References: <87a9kkax0j.fsf@xmission.com> <8761v7h2pt.fsf@tw-ebiederman.twitter.com> <87li281wx6.fsf_-_@xmission.com> <87ob28kqks.fsf_-_@xmission.com> <8761ogkqhl.fsf_-_@xmission.com> <20140218171252.GC4026@tucsk.piliscsaba.szeredi.hu> <87ha7wrtyz.fsf@xmission.com> <20140219132319.79bc3b26bad00a513880d207@canb.auug.org.au> Date: Mon, 24 Feb 2014 15:43:34 -0800 In-Reply-To: <20140219132319.79bc3b26bad00a513880d207@canb.auug.org.au> (Stephen Rothwell's message of "Wed, 19 Feb 2014 13:23:19 +1100") Message-ID: <87ios4gjq1.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX18Z+9PwxM4p19MAUtQXur7GPuI7OK47s4Y= X-SA-Exim-Connect-IP: 98.207.154.105 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 3.1 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0006] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.5 XM_Body_Dirty_Words Contains a dirty word * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *;Stephen Rothwell X-Spam-Relay-Country: Subject: Re: [PATCH 03/11] vfs: Don't allow overwriting mounts in the current mount namespace X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 14:26:46 -0700) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stephen Rothwell writes: > On Tue, 18 Feb 2014 14:20:29 -0800 Linus Torvalds wrote: >> >> For this kind of function return value it actually tends to work very >> well, and in fact often generates slightly better code than "int". So >> I don't _hate_ bool, and we've certainly had a lot more use creep in >> lately, but I also don't really see "bool" as much of an upside. > > And in function declarations, it makes it very obvious that the function > is not one of our "return 0 or -ERROR" ones. So I played with this instance in particular. The only difference winds up being by the bool version uses byte instructions on %al and %bl instead of their 32 bit interger equivalents on %eax and %ebx. I also benchmarked the difference and on the most sensitive test I could find. will-it-scale/unlink2 (aka create,close,unlink each process in a separate directory). There were no measurable performance differences. So for purposes of better documentation I have changed the function, and I will repost my patches shortly. Eric