From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73A84E732FD for ; Thu, 28 Sep 2023 17:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231939AbjI1RG3 (ORCPT ); Thu, 28 Sep 2023 13:06:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231285AbjI1RGV (ORCPT ); Thu, 28 Sep 2023 13:06:21 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A8D16193; Thu, 28 Sep 2023 10:06:19 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9B31C433C8; Thu, 28 Sep 2023 17:06:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695920779; bh=DNM/VlOuUT51G0bnMvXw+94sqfHee3c68K5vLwQuau4=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=T1EG9wCsmdavqbCDgZQmRYDY2hTjqQ8HvqU7HakqZRoba0+m8x7Xb0PPxNH54fTbK gxOvKBrhR/NUHAqOFYLgQFvCS4fbqqpdpyJ0meCz+VJBZB5WwUDXaofxixCnDwGA2b xVhvTR3lvjwhcUNCr4cL+zM4prum42dBj/EqssN3wQ5xwZohTtnO5wenm4djJ5rTsg au+O/I2DWLjGqSGQ9+pJFDrXNkgJ5uSZlH8zfxoOHymWjEqjSumVZbYplcXqZfm3+f KDfZ0aAr31be94G8szYCClaMWLFdZEYGpG76Y3w4tHoT3E7mgxWznMj5HFQTi8O+xa SaKUjb/2UX2Ww== Message-ID: Subject: Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers From: Jeff Layton To: Arnd Bergmann , Alexander Viro , Christian Brauner , Linus Torvalds , David Sterba , Amir Goldstein , Theodore Ts'o , "Eric W. Biederman" , Kees Cook , Jeremy Kerr , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Greg Kroah-Hartman , Arve =?ISO-8859-1?Q?Hj=F8nnev=E5g?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Mattia Dongili , Dennis Dalessandro , Jason Gunthorpe , Leon Romanovsky , Brad Warrum , Ritu Agarwal , Hans de Goede , Ilpo =?ISO-8859-1?Q?J=E4rvinen?= , Mark Gross , Jiri Slaby , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , Christian Schoenebeck , David Sterba , David Howells , Marc Dionne , Ian Kent , Luis de Bethencourt , Salah Triki , "Tigran A. Aivazian" , Chris Mason , Josef Bacik , Xiubo Li , Ilya Dryomov , Jan Harkes , coda@cs.cmu.edu, Joel Becker , Christoph Hellwig , Nicolas Pitre , "Rafael J . Wysocki" , Ard Biesheuvel , Gao Xiang , Chao Yu , Yue Hu , Jeffle Xu , Namjae Jeon , Sungjong Seo , Jan Kara , Andreas Dilger , Jaegeuk Kim , OGAWA Hirofumi , Christoph Hellwig , Miklos Szeredi , Bob Peterson , Andreas Gruenbacher , Richard Weinberger , Anton Ivanov , Johannes Berg , Mikulas Patocka , Mike Kravetz , Muchun Song , Jan Kara , David Woodhouse , Dave Kleikamp , Tejun Heo , Trond Myklebust , Anna Schumaker , Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Ryusuke Konishi , Anton Altaparmakov , Konstantin Komarov , Mark Fasheh , Joseph Qi , Bob Copeland , Mike Marshall , Martin Brandenburg , Luis Chamberlain , Iurii Zaikin , Tony Luck , "Guilherme G. Piccoli" , Anders Larsen , Steve French , Paulo Alcantara , Ronnie Sahlberg , Shyam Prasad N , Sergey Senozhatsky , Phillip Lougher , Steven Rostedt , Masami Hiramatsu , Evgeniy Dushistov , Chandan Babu R , "Darrick J. Wong" , Damien Le Moal , Naohiro Aota , Johannes Thumshirn , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Hugh Dickins , Andrew Morton , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-rdma@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, v9fs@lists.linux.dev, linux-afs@lists.infradead.org, autofs@vger.kernel.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, codalist@coda.cs.cmu.edu, linux-efi@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, gfs2@lists.linux.dev, linux-um@lists.infradead.org, linux-mtd@lists.infradead.org, jfs-discussion@lists.sourceforge.net, linux-nfs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev, linux-karma-devel@lists.sourceforge.net, devel@lists.orangefs.org, linux-unionfs@vger.kernel.org, linux-hardening@vger.kernel.org, reiserfs-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, linux-trace-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, bpf@vger.kernel.org, Netdev , apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Date: Thu, 28 Sep 2023 13:06:03 -0400 In-Reply-To: <6020d6e7-b187-4abb-bf38-dc09d8bd0f6d@app.fastmail.com> References: <20230928110554.34758-1-jlayton@kernel.org> <20230928110554.34758-2-jlayton@kernel.org> <6020d6e7-b187-4abb-bf38-dc09d8bd0f6d@app.fastmail.com> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) MIME-Version: 1.0 Precedence: bulk List-ID: On Thu, 2023-09-28 at 11:48 -0400, Arnd Bergmann wrote: > On Thu, Sep 28, 2023, at 07:05, Jeff Layton wrote: > > This shaves 8 bytes off struct inode, according to pahole. > >=20 > > Signed-off-by: Jeff Layton >=20 > FWIW, this is similar to the approach that Deepa suggested > back in 2016: >=20 > https://lore.kernel.org/lkml/1452144972-15802-3-git-send-email-deepa.kern= el@gmail.com/ >=20 > It was NaKed at the time because of the added complexity, > though it would have been much easier to do it then, > as we had to touch all the timespec references anyway. >=20 > The approach still seems ok to me, but I'm not sure it's worth > doing it now if we didn't do it then. >=20 I remember seeing those patches go by. I don't remember that change being NaK'ed, but I wasn't paying close attention at the time=20 Looking at it objectively now, I think it's worth it to recover 8 bytes per inode and open a 4 byte hole that Amir can use to grow the i_fsnotify_mask. We might even able to shave off another 12 bytes eventually if we can move to a single 64-bit word per timestamp.=20 It is a lot of churn though. --=20 Jeff Layton