It's hard for me to imagine using it for anything myself, considering the number of times I do something like run a search (or a backup command) across literally every file I care about.
Most modern applications are not designed to operate on shared files like this so in general 'noatime' is safe for 99.9% of software.
It's completely reasonable to turn it on. And also, when you're writing applications for Linux, consider using the `O_NOATIME` flag in your file opens.
As a former sysadmin through the dotcom booms, we regularly depended on atime for identifying which files are actively being used in myriad situations.
Sometimes you're just confirming a config file was actually reloaded in response to your HUP signal. Other times you're trying to find out which data files a customer's cgi-bin mess is making use of.
It's probably less relevant today where multi-user unix hosts are less common, but it was quite valuable information to maintain back then.
Systemd in a way does. One of the systemd-tmpfiles entry option is to clean up unused files after some time (it ships defaults for /tmp/ after 10 days and /var/tmp/ after 30 days) and for this it checks atime, mtime and ctime to determin if it should delete the file (I think you can also take a flock on the file to prevent it from being deleted as well)
This indicates to me a very poor design. If not, it is a validation of the old UNIX saying "do one thing and do it well" and "keep programs small" (paraphrasing).
> I admit, I do not fully understand systemd ...
> This indicates to me a very poor design. If not, it is a validation of the old UNIX saying "do one thing and do it well" and "keep programs small" (paraphrasing).
This isn't a systemd problem, systemd just makes use of cgroups. The kernel has a degenerate case handling lazy atime updates combined with cgroups.
I’d say it’s both a systemd issue and a kernel issue. The fact that systemd motivates kernel fixes does point to systemd being maybe just a bit overengineered
systemd is basically a victim here, you're quasi engaging in a tech form of victim blaming.
don't blame systemd for making use of kernel features (cgroups)
and without cgroups linux has no sandboxing capabilities, and would be largely irrelevant to today's workloads
Look if I wrote a thing that caused kernel lockups then I’d blame myself even if the kernel dudes fixed the issue
https://youtu.be/Au15lSiAkeQ?si=sxxP2ia9vUkWY5qy&t=982
From the YouTube transcript:
"I don't know what systemd is doing to take so long cuz this is the rub systemd essentially takes 100% CPU twice over. So on our two core machine that we run these things on, I can run top that when I actually got it, I said to you the machine was unresponsive, right? Because all in kernel land, locks are being taken out left, right, and center. Um, you know, we're trying to mount these things in parallel at sensible levels because we want to try and mount"
CaliforniaKarl•1h ago
themafia•1h ago