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#1 2014-12-22 05:15:29

jernst
Member
From: Silicon Valley
Registered: 2014-03-04
Posts: 290
Website

cgroup mounts

I'm trying to understand this:

# mount | grep cgroup
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)

Some questions:

  • Just what is doing all that mounting? Is that systemd? Does it always do that, or is that configurable somewhere?

  • Can I mount those things manually, and if so, what would a command-line look like for it?

  • Just what is the thing being mounted here? (Presumably it's one "thing" that just gets mounted with different arguments every time)

  • What exactly do all these mounts do? Is there some documentation somewhere that explains these different mounts? (I haven't found any, but perhaps I haven't looked in the right places)

  • If I unmount some of them, what breaks, and how would I know what the dependencies are?

Puzzled ... this is not my grandmother's mount any more.

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#2 2014-12-22 11:40:31

Lone_Wolf
Member
From: Netherlands, Europe
Registered: 2005-10-04
Posts: 11,866

Re: cgroup mounts

cgroups aka computer groups are a kernel feature to manage resources (cpu, emory etc) .

These links should help to get an idea about them :
https://en.wikipedia.org/wiki/Cgroups
https://wiki.archlinux.org/index.php/Cgroup


Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.


(A works at time B)  && (time C > time B ) ≠  (A works at time C)

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#3 2014-12-22 16:59:12

jernst
Member
From: Silicon Valley
Registered: 2014-03-04
Posts: 290
Website

Re: cgroup mounts

Yeah, I have some understanding of cgroups, but I'd like the understand the mechanics of the mount. It's not like there's an entry in /etc/fstab.

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#4 2014-12-23 00:37:15

Alad
Wiki Admin/IRC Op
From: Bagelstan
Registered: 2014-05-04
Posts: 2,407
Website

Re: cgroup mounts

Is that systemd?

Yes. Rest is up for grabs on google...


Mods are just community members who have the occasionally necessary option to move threads around and edit posts. -- Trilby

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