Re: Documenting MS_LAZYTIME

[Austin S Hemmelgarn <ahferroin7@xxxxxxxxx>]

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.