>> In the past, atime updates used to ruin performance.  Thanks to work by Ted
>> Ts'o and others, that penalty has been greatly reduced (but not eliminated)
>> by two options:
>> * relatime (on by default): atime is not updated unless atime<=mtime or
>>    atime<NOW-24h
>> * lazytime (off by default): atime and mtime updates are postponed by up to
>>    30 minutes, unless there's memory pressure or the inode has to be written
>>    for another reason

>> But alas, there are more considerations than just performance:
>> * atime is really nasty for any CoW filesystems (btrfs, zfs, lvm snapshots,
>>    qcow2 snapshots, deduped thin storage, etc).  For a /usr-y mix of files,
>>    it costs around 5% of disk space per snapshot.  relatime offers no help as
>>    its threshold (24h) just happens to match the most popular snapshot and
>>    cronjob frequency (once per day).  Even worse, it can make _reading_
>>    things result in ENOSPC!
>> * atime murders media with sharply limited write endurance, such as SD
>>    cards.  For this reason, every SoC pre-made image I've seen ships with
>>    noatime.

>> And what do we get in return?
>> * the "vote" field in popcon.  This somewhat benefits the distribution (lets
>>    us spot low-use packages installed by default, such as xterm (53.60% inst,
>>    6.67% vote) or tcpd (95.20% inst, 9.85% vote)) but gives no gain to
>>    individual users.
>> * some rare forensic uses
>> * new mail notification on login