From 42a8e396cf0716cd123f1ca0666ba043f89131b4 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Fri, 20 Feb 2015 09:50:01 +0100 Subject: [PATCH] mount.2: Document MS_LAZYTIME Based on Ted T'so's commit message 0ae45f63d4e Reviewed-by: Eric Sandeen Reviewed-by: Andreas Dilger Cowritten-by: Theodore Ts'o Signed-off-by: Michael Kerrisk --- man2/mount.2 | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/man2/mount.2 b/man2/mount.2 index b081ba1ea..a0b9550d6 100644 --- a/man2/mount.2 +++ b/man2/mount.2 @@ -151,6 +151,32 @@ Make directory changes on this filesystem synchronous. or subtrees using .BR chattr (1).) .TP +.BR MS_LAZYTIME " (since Linux 3.20)" +.\" commit 0ae45f63d4ef8d8eeec49c7d8b44a1775fff13e8 +.\" commit fe032c422c5ba562ba9c2d316f55e258e03259c6 +.\" commit a26f49926da938f47561f386be56a83dd37a496d +Reduce on-disk updates of inode timestamps (atime, mtime, ctime) +by maintaining these changes only in memory. +The on-disk timestamps are updated only when: +.RS +.IP (a) 5 +the inode needs to be updated for some change unrelated to file timestamps; +.IP (b) +the application employs +.BR fsync (2), +.BR syncfs (2), +or +.BR sync (2); +.IP (c) +an undeleted inode is evicted from memory; or +.IP (d) +more than 24 hours have passed since the inode was written to disk. +.RE +.IP +This mount option significantly reduces writes to the inode table +for some workloads +(e.g., when performing frequent random writes to preallocated files). +.TP .B MS_MANDLOCK Permit mandatory locking on files in this filesystem. (Mandatory locking must still be enabled on a per-file basis,