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 60D24CE7A95 for ; Mon, 25 Sep 2023 10:17:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230063AbjIYKRY (ORCPT ); Mon, 25 Sep 2023 06:17:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229564AbjIYKRX (ORCPT ); Mon, 25 Sep 2023 06:17:23 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9ED309F; Mon, 25 Sep 2023 03:17:17 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BC36C433C8; Mon, 25 Sep 2023 10:17:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695637037; bh=iRlJHmpvIWYSQoj21tvtV2DoXT4u3L4h+gWlWYry4PM=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=NIfRXmW1lLGxqAV/3eDoSAlnVOJLZ47aAU/jKqo58kbnYax2KcWGFD2loAF340lGJ sFIB23H5PgnpEhlFlj1gFBkIhw+0As+UPG1MLX3Gj1H4jM6VkUOyRkf8tv/GeGI9HH wZDSUZTCY+UdvbGFdSFtWPzEEcVKwfLOSNpiYUm2U8/MPSCmqp2waTGLv3H+UJJZre ARpA0/puvMLsKXBC5yWqfaH770rGku8aA3R7DBpURcYI1Iihb0mjWqqTZ4HzIutDX+ DggWMd4j+g2WtmHR5gnN0TvTiLkHmayeP81udlLo8BZsmg9sPvcH97J0augzlIDXyD xcklk5YYnYzOg== Message-ID: <9b81a1f52b4dc777dbb5259b2e12e90eba0ff507.camel@kernel.org> Subject: Re: [PATCH v8 0/5] fs: multigrain timestamps for XFS's change_cookie From: Jeff Layton To: NeilBrown , Christian Brauner Cc: Alexander Viro , Chuck Lever , Olga Kornievskaia , Dai Ngo , Tom Talpey , Chandan Babu R , "Darrick J. Wong" , Dave Chinner , Jan Kara , Linus Torvalds , Kent Overstreet , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org Date: Mon, 25 Sep 2023 06:17:14 -0400 In-Reply-To: <169559548777.19404.13247796879745924682@noble.neil.brown.name> References: <20230922-ctime-v8-0-45f0c236ede1@kernel.org> , <20230924-mitfeiern-vorladung-13092c2af585@brauner> <169559548777.19404.13247796879745924682@noble.neil.brown.name> 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: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, 2023-09-25 at 08:44 +1000, NeilBrown wrote: > On Sun, 24 Sep 2023, Christian Brauner wrote: > > > My initial goal was to implement multigrain timestamps on most major > > > filesystems, so we could present them to userland, and use them for > > > NFSv3, etc. > >=20 > > If there's no clear users and workloads depending on this other than fo= r > > the sake of NFS then we shouldn't expose this to userspace. We've tried > > this and I'm not convinced we're getting anything other than regression= s > > out of it. Keep it internal and confined to the filesystem that actuall= y > > needs this. > >=20 >=20 > Some NFS servers run in userspace, and they would a "clear user" of this > functionality. >=20 Indeed. Also, all of the programs that we're concerned about breaking here (make, rsync, etc.) could benefit from proper fine-grained timestamps: Today, when they see two identical timestamps on files, these programs have to assume the worst: rsync has to do the copy, make has to update the target, etc. With a real distinguishable fine-grained timestamps, these programs would likely be more efficient and some of these unneeded operations would be avoided. --=20 Jeff Layton