From: Eric Sandeen Subject: Re: Documenting MS_LAZYTIME Date: Mon, 23 Feb 2015 10:24:54 -0600 Message-ID: <54EB5456.5030607@redhat.com> References: <54E7578E.4090809@redhat.com> <20150221025636.GB7922@thunk.org> <54EB1B19.8050808@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 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: Austin S Hemmelgarn , "Theodore Ts'o" Return-path: In-Reply-To: <54EB1B19.8050808-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org 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 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html