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All About the Linux Kernel: Cgroup's Redesign (Linux.com)

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 15, 2013 21:47 UTC (Thu) by ovitters (subscriber, #27950)
In reply to: All About the Linux Kernel: Cgroup's Redesign (Linux.com) by Cyberax
Parent article: All About the Linux Kernel: Cgroup's Redesign (Linux.com)

LWN could do without "uder-iditic", "traditional Linux API", "ugly monster", "whines" and incorrect spellings like SystemD (it is systemd). Thanks in advance.


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All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 15, 2013 22:18 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link]

It's a little bit trollish, sure. But nevertheless, it's true.

Right now cgroups is a traditional filesystem-based API which can be manipulated by pretty much anything. It supports usual delegation - just set the appropriate permissions on the filesystem and bind-mount it in a namespace.

Tejun Heo wants to replace it with a single daemon. No plans for delegation or access control are presented so far.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 8:21 UTC (Fri) by ovitters (subscriber, #27950) [Link]

I am and was not disagreeing with what you said. I know too little to have a real opinion on this. :P

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 17, 2013 6:15 UTC (Sat) by Rudd-O (guest, #61155) [Link]

You're blatantly misinforming people.

Stop.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 17, 2013 15:47 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link]

No, I'm not.

There's a plan to add a new kernel option ('insane_behavior=1') to cgroups, which will:
1) Join them into a single hierarchy.
2) Disallow changing ownership and access rights.
3) Lock cgroups for modifications, except by one process.

So yes, technically filesystem interface won't go away. It just will be completely useless.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 14:27 UTC (Fri) by SEJeff (subscriber, #51588) [Link]

Funnily enough, I agree with both of you. Cyberax's points are entirely valid. As someone who likes to use cgroups and their various incarnations to manually carve up systems for maximum performance and utilization, the echo / mkdir / rmdir based interface is a breeze. Rolling this all into systemd is not going to negate, but make what I currently do quite easily very very difficult.

Myself and many others in the HPC industry are likely not pleased with this decision whatsoever. That being said, I do love systemd overall, just not this specific part of it.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 15:09 UTC (Fri) by ovitters (subscriber, #27950) [Link]

So make noise, but make sure it is the right noise. Saying the decision is terrible for X,Y,Z is ok. But as soon as it includes "OMG Lennart" or anything similar I'd just zone out and not listen anymore. Which is bad if your criticism was valid&important.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 16:13 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link]

Well, "OMG Lennart" is also a good way to start a flame war which might attract interest to the topic :)

BTW: I really like systemd/journal/etc. overall.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 15:36 UTC (Fri) by raven667 (subscriber, #5198) [Link]

Engaging with the cgroups and systemd maintainers where they congregate so that you understand the problems they are facing and they understand the problems you are solving is going to be the best way to make sure that your use cases are handled in ways that are acceptable to you. The reason that systemd maintainers are at the head of the table is that this software is the most visible and widely deployed user of the cgroups interface and they are engaged with the cgroup maintainers. Anyone who relies on this interface who sits back and waits is going to be disappointed and frustrated if their needs aren't anticipated and met.

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 16, 2013 16:12 UTC (Fri) by Cyberax (✭ supporter ✭, #52523) [Link]

I think people told them multiple times that this is a bad idea, including guys from Google and other Linux maintainers.

Maybe talking with them at the Kernel Summit will help?

All About the Linux Kernel: Cgroup's Redesign (Linux.com)

Posted Aug 17, 2013 6:16 UTC (Sat) by Rudd-O (guest, #61155) [Link]

Cgroups are not being rolled into systemd. You will still be able to do cd mkdir and mv and whatever.

Stop misinforming people.


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