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 lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6CAD1EE49A4 for ; Sun, 10 Sep 2023 22:01:44 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-3.v29.lw.sourceforge.com) by sfs-ml-3.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1qfSUw-0007Sy-HQ; Sun, 10 Sep 2023 22:01:41 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-3.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1qfSUv-0007Sr-3l for linux-f2fs-devel@lists.sourceforge.net; Sun, 10 Sep 2023 22:01:39 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=EyybjuBSw2AsBAibBPVqGccWs6P0JtTeGBB0Kwx90Dw=; b=GxLS9Ez5aG8cq6OyoELCyx27aC wN715ueMmesRMFX/+TgNwyqjJxrSCIK8p2dsFple1v1tKVLOlMj6oJeOgIttxbY/4L7bxJmBZI3CT snH6YrtcIxJUiBNzlci92XUuIncGNQvjqn5OCw4xN6DIo88mIJBsvyDOsOVwk7ArpSvA=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=EyybjuBSw2AsBAibBPVqGccWs6P0JtTeGBB0Kwx90Dw=; b=KEN3StVPFEpC/qxznygayb3Zxn raPKHdLxtFnzdzr8fzoOgKUy5F/KxCW6A4/qtiSEorhN6t3F3WhRfw4i/Ug2V0yfEdvoqzSIAWcQI /F4ty7bK3j7g6xAyNB5/nbAH0nmWsKt9y1fzznUWa8jB5uZgx/lHQhE0kruQC/hKOPl4=; Received: from mail-pf1-f173.google.com ([209.85.210.173]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.95) id 1qfSUn-00H6OD-ES for linux-f2fs-devel@lists.sourceforge.net; Sun, 10 Sep 2023 22:01:39 +0000 Received: by mail-pf1-f173.google.com with SMTP id d2e1a72fcca58-68fb6fd2836so844474b3a.0 for ; Sun, 10 Sep 2023 15:01:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fromorbit-com.20230601.gappssmtp.com; s=20230601; t=1694383288; x=1694988088; darn=lists.sourceforge.net; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=EyybjuBSw2AsBAibBPVqGccWs6P0JtTeGBB0Kwx90Dw=; b=JYBnUClFEwwWETTtpWatD63J5oKDWJ0ovBYfCA03V9iG5tk6+R3gDGrNqao3Gt5ndK ZfM2jnvnWUlf6LJn97bnwx/vEN4XkvR55bn8DqOU95W9/j/LhPxRdON+nF/tSmhtjFAn xpSKJodqydi+tTlg/E3+AqqurVs1fBUf9I/xOID6+YoenOyRbkJre/U49QrPwRfuSbaq CHoiibwzTDv09x/wbPGbx+ZClmOwZtXTfk3F/hAh5eUGjujFOP2F57OeR0PqnUjtZZqL HGj6gx7r43mXgNpAUoAOj5aEAS1qzSMhAIgDBQZjUMzGfh4ATZd3l9YEcGGmZghfj7Kk XfIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694383288; x=1694988088; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=EyybjuBSw2AsBAibBPVqGccWs6P0JtTeGBB0Kwx90Dw=; b=IHDs34FSI2b45HbF7i8jm+9jHiRdKd+PBMeKvjDDayFGec5kZUsJIWn7IhQnHw3RD/ CpIlBRg3UVXyzHzKUjeIt9fkpYXQReV4xX1dfULnkprv3Xc5Nq8yuqimtdGvtl9WmIdM IZxhIWuN/ArcgCKQ9WS5lfago6Ggoe4KCGmP72eT4FeHhjwugTI4MNaLIh/UdzrEwt9E J5RKHl6wtl81+iB+w14VnAoiJO/hPrsxUMRKTuZvRK1Un/DDIba814HY8G7uIE9C69P5 E/U0Ho+yGQZNZLPAPc3PyKa/oGeu5jc8o8HfqE8YqEET8JyPb2uDlXd/2tKMZoXqcfWM vR3g== X-Gm-Message-State: AOJu0YwSJv/DVMq+FKSMVLH6mjnIQ32itzfh9Po17QjaQjxPPRoqzEOP CtYI7Lr4Z9MNinfQR3wxRWqNCg== X-Google-Smtp-Source: AGHT+IHSYFPf3w2qdTZr9bikkzuSsvPYQjYYZyW+Zfc616rQWXs3Eeo2BzwinmhhOfJVOtnHj1lBTA== X-Received: by 2002:a05:6a00:1a0c:b0:68c:57c7:1eb0 with SMTP id g12-20020a056a001a0c00b0068c57c71eb0mr9371853pfv.11.1694383287795; Sun, 10 Sep 2023 15:01:27 -0700 (PDT) Received: from dread.disaster.area (pa49-195-66-88.pa.nsw.optusnet.com.au. [49.195.66.88]) by smtp.gmail.com with ESMTPSA id u10-20020a62ed0a000000b0068a3dd6c1dasm4403641pfh.142.2023.09.10.15.01.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Sep 2023 15:01:27 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1qfSUe-00DWBA-0u; Mon, 11 Sep 2023 08:01:24 +1000 Date: Mon, 11 Sep 2023 08:01:24 +1000 To: Pavel Begunkov Message-ID: References: <20230827132835.1373581-1-hao.xu@linux.dev> <20230827132835.1373581-8-hao.xu@linux.dev> <642de4e6-801d-fcad-a7ce-bfc6dec3b6e5@linux.dev> <6489b8cb-7d54-1e29-f192-a3449ed87fa1@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <6489b8cb-7d54-1e29-f192-a3449ed87fa1@gmail.com> X-Headers-End: 1qfSUn-00H6OD-ES Subject: Re: [f2fs-dev] [PATCH 07/11] vfs: add nowait parameter for file_accessed() X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Dave Chinner via Linux-f2fs-devel Reply-To: Dave Chinner Cc: Wanpeng Li , "Darrick J . Wong" , Dominique Martinet , linux-unionfs@vger.kernel.org, linux-mm@kvack.org, Stefan Roesch , Clay Harris , linux-s390@vger.kernel.org, linux-nilfs@vger.kernel.org, Matthew Wilcox , codalist@coda.cs.cmu.edu, cluster-devel@redhat.com, linux-cachefs@redhat.com, linux-ext4@vger.kernel.org, Hao Xu , linux-cifs@vger.kernel.org, ecryptfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-block@vger.kernel.org, Alexander Viro , io-uring@vger.kernel.org, Jens Axboe , Christian Brauner , netdev@vger.kernel.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, devel@lists.orangefs.org, linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, bpf@vger.kernel.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Fri, Sep 08, 2023 at 01:29:55AM +0100, Pavel Begunkov wrote: > On 9/3/23 23:30, Dave Chinner wrote: > > On Wed, Aug 30, 2023 at 02:11:31PM +0800, Hao Xu wrote: > > > On 8/29/23 19:53, Matthew Wilcox wrote: > > > > On Tue, Aug 29, 2023 at 03:46:13PM +0800, Hao Xu wrote: > > > > > On 8/28/23 05:32, Matthew Wilcox wrote: > > > > > > On Sun, Aug 27, 2023 at 09:28:31PM +0800, Hao Xu wrote: > > > > > > > From: Hao Xu > > > > > > > > > > > > > > Add a boolean parameter for file_accessed() to support nowait semantics. > > > > > > > Currently it is true only with io_uring as its initial caller. > > > > > > > > > > > > So why do we need to do this as part of this series? Apparently it > > > > > > hasn't caused any problems for filemap_read(). > > > > > > > > > > > > > > > > We need this parameter to indicate if nowait semantics should be enforced in > > > > > touch_atime(), There are locks and maybe IOs in it. > > > > > > > > That's not my point. We currently call file_accessed() and > > > > touch_atime() for nowait reads and nowait writes. You haven't done > > > > anything to fix those. > > > > > > > > I suspect you can trim this patchset down significantly by avoiding > > > > fixing the file_accessed() problem. And then come back with a later > > > > patchset that fixes it for all nowait i/o. Or do a separate prep series > > > > > > I'm ok to do that. > > > > > > > first that fixes it for the existing nowait users, and then a second > > > > series to do all the directory stuff. > > > > > > > > I'd do the first thing. Just ignore the problem. Directory atime > > > > updates cause I/O so rarely that you can afford to ignore it. Almost > > > > everyone uses relatime or nodiratime. > > > > > > Hi Matthew, > > > The previous discussion shows this does cause issues in real > > > producations: https://lore.kernel.org/io-uring/2785f009-2ebb-028d-8250-d5f3a30510f0@gmail.com/#:~:text=fwiw%2C%20we%27ve%20just%20recently%20had%20similar%20problems%20with%20io_uring%20read/write > > > > > > > Then separate it out into it's own patch set so we can have a > > discussion on the merits of requiring using noatime, relatime or > > lazytime for really latency sensitive IO applications. Changing code > > is not always the right solution... > > Separation sounds reasonable, but it can hardly be said that only > latency sensitive apps would care about >1s nowait/async submission > delays. Presumably, btrfs can improve on that, but it still looks > like it's perfectly legit for filesystems do heavy stuff in > timestamping like waiting for IO. Right? Yes, it is, no-one is denying that. And some filesystems are worse than others, but none of that means it has to be fixed so getdents can be converted to NOWAIT semantics. ie. this patchset is about the getdents NOWAIT machinery, and fiddling around with timestamps has much, much wider scope than just NOWAIT getdents machinery. We'll have this discussion about NOWAIT timestamp updates when a RFC is proposed to address the wider problem of how timestamp updates should behave in NOWAIT context. -Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel