On Mon, 2015-12-14 at 22:30 +0100, Lionel Bouton wrote: > Mutt is often used as an example but tmpwatch uses atime by default > too > and it's quite useful. Hmm one could probably argue that these few cases justify the use of separate filesystems (or btrfs subvols ;) ), so that the majority could benefit of noatime.
> If you have a local cache of remote files for which you want a good > hit > ratio and don't care too much about its exact size (you should have > Nagios/Zabbix/... alerting you when a filesystem reaches a %free > limit > if you value your system's availability anyway), using tmpwatch with > cron to maintain it is only one single line away and does the job. > For > an example of this particular case, on Gentoo the > /usr/portage/distfiles > directory is used in one of the tasks you can uncomment to activate > in > the cron.daily file provided when installing tmpwatch. > Using tmpwatch/cron is far more convenient than using a dedicated > cache > (which might get tricky if the remote isn't HTTP-based, like an > rsync/ftp/nfs/... server or doesn't support HTTP IMS requests for > example). > Some http frameworks put sessions in /tmp: in this case if you want > sessions to expire based on usage and not creation time, using > tmpwatch > or similar with atime is the only way to clean these files. This can > even become a performance requirement: I've seen some servers slowing > down with tens/hundreds of thousands of session files in /tmp because > it > was only cleaned at boot and the systems were almost never > rebooted... Okay there are probably some usecases, ... the session cleaning I'd however rather consider a bug in the respective software, especially if it really depends on it to expire the session (what if for some reason tmpwatch get's broken, uninstalled, etc.) > I use noatime and nodiratime FYI: noatime implies nodiratime :-) > Finally Linus Torvalds has been quite vocal and consistent on the > general subject of the kernel not breaking user-space APIs no matter > what so I wouldn't have much hope for default kernel mount options > changes... He surely is right in general,... but when the point has been reached, where only a minority actually requires the feature... and the minority actually starts to suffer from that... it may change. Cheers, Chris.
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