From: "Michael Kerrisk (man-pages)" Subject: Re: Documenting MS_LAZYTIME Date: Fri, 20 Feb 2015 14:22:07 +0100 Message-ID: References: <44893EA7-B11A-469A-9911-6CE2E8B26EB4@dilger.ca> Reply-To: mtk.manpages@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "Theodore Ts'o" , Ext4 Developers List , Linux btrfs Developers List , XFS Developers , linux-man , Linux-Fsdevel , Linux API To: Andreas Dilger Return-path: Received: from mail-lb0-f181.google.com ([209.85.217.181]:34106 "EHLO mail-lb0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750780AbbBTNWa convert rfc822-to-8bit (ORCPT ); Fri, 20 Feb 2015 08:22:30 -0500 In-Reply-To: <44893EA7-B11A-469A-9911-6CE2E8B26EB4@dilger.ca> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 20 February 2015 at 13:32, Andreas Dilger wrote: > On Feb 20, 2015, at 1:50 AM, Michael Kerrisk = wrote: >> >> Hello Ted, >> >> Based on your commit message 0ae45f63d4e, I I wrote the documentatio= n >> below for MS_LAZYTIME, to go into the mount(2) man page. Could you >> please check it over and let me know if it's accurate. In particular= , >> I added pieces marked with "*" below that were not part of the commi= t >> message and I'd like confirmation that they're accurate. >> >> Thanks, >> >> Michael >> >> [[ >> MS_LAZYTIME (since Linux 3.20) >> Only update filetimes (atime, mtime, ctime) on the in= - >> memory version of the file inode. The on-disk time= =E2=80=90 >> stamps are updated only when: >> >> (a) the inode needs to be updated for some change unre= =E2=80=90 >> lated to file timestamps; >> >> (b) the application employs fsync(2), syncfs(2), o= r >> sync(2); >> >> (c) an undeleted inode is evicted from memory; or >> >> * (d) more than 24 hours have passed since the i-node w= as >> * written to disk. >> >> This mount option significantly reduces writes to th= e >> inode table for workloads that perform frequent rando= m >> writes to preallocated files. >> >> * As at Linux 3.20, this option is supported only on ext= 4. > > I _think_ that the lazytime mount option is generic for all filesyste= ms. > I believe ext4 has an extra optimization for it, but that's it. Ah yes, looking at the code again, that makes sense. I think you're right, and I've struck that last sentence. Thanks, Andreas. Cheers, Michael --=20 Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html