From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:59785 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752548AbbBWQZE (ORCPT ); Mon, 23 Feb 2015 11:25:04 -0500 Message-ID: <54EB5456.5030607@redhat.com> Date: Mon, 23 Feb 2015 10:24:54 -0600 From: Eric Sandeen MIME-Version: 1.0 To: Austin S Hemmelgarn , "Theodore Ts'o" CC: Michael Kerrisk , Ext4 Developers List , Linux btrfs Developers List , XFS Developers , linux-man@vger.kernel.org, Linux-Fsdevel , Linux API Subject: Re: Documenting MS_LAZYTIME References: <54E7578E.4090809@redhat.com> <20150221025636.GB7922@thunk.org> <54EB1B19.8050808@gmail.com> In-Reply-To: <54EB1B19.8050808@gmail.com> Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2/23/15 6:20 AM, Austin S Hemmelgarn wrote: > On 2015-02-20 21:56, Theodore Ts'o wrote: >> On Fri, Feb 20, 2015 at 09:49:34AM -0600, Eric Sandeen wrote: >>> >>>> This mount option significantly reduces writes to the >>>> inode table for workloads that perform frequent random >>>> writes to preallocated files. >>> >>> This seems like an overly specific description of a single workload out >>> of many which may benefit, but what do others think? "inode table" is also >>> fairly extN-specific. >> >> How about somethign like "This mount significantly reduces writes >> needed to update the inode's timestamps, especially mtime and actime. >> Examples of workloads where this could be a large win include frequent >> random writes to preallocated files, as well as cases where the >> MS_STRICTATIME mount option is enabled."? >> >> (The advantage of MS_STRICTATIME | MS_LAZYTIME is that stat system >> calls will return the correctly updated atime, but those atime updates >> won't get flushed to disk unless the inode needs to be updated for >> file system / data consistency reasons, or when the inode is pushed >> out of memory, or when the file system is unmounted.) >> > If you want to list some specific software, it should help with > anything that uses sqlite (which notably includes firefox and > chrome), as well as most RDMS software and systemd-journald. I'm really uneasy with starting to list specific workloads and applications here. It's going to get dated quickly, and will lead to endless cargo-cult tuning. I'd strongly prefer to just describe what it does (reduces the number of certain metadata writes to disk) and leave it at that.... -Eric