From: Austin S Hemmelgarn Subject: Re: Documenting MS_LAZYTIME Date: Mon, 23 Feb 2015 07:20:41 -0500 Message-ID: <54EB1B19.8050808@gmail.com> References: <54E7578E.4090809@redhat.com> <20150221025636.GB7922@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Michael Kerrisk , Ext4 Developers List , Linux btrfs Developers List , XFS Developers , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linux-Fsdevel , Linux API To: Theodore Ts'o , Eric Sandeen Return-path: In-Reply-To: <20150221025636.GB7922-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org 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.