Decent description in the readme, but could not find the part that explains "what does this buy me?"
Finally, it came down to:
"This gives the applications the impression of running exclusively on a machine."
OK but as an outsider that still doesn't tell me what it buys me (or what it buys you, or Google).
(By outsider, I mean I have reasonable ability to administer my own Linux system, but wouldn't trust myself to do so in a production environment... so I'm not up on the latest practices in system administration or especially Google-scale system administration.)
Setting aside whether I need it (I'm pretty sure I don't, so no need to tell me that) I'm really curious what this is good for. Can someone explain it in more lay person's terms? Sounds like applications can still stomp on each others files, and consume memory that then takes away from what's available for other applications, so what is the benefit?
I'm not questioning that there's a benefit, just wondering what it is, and how this is used.
cgroups (and lmctfy) does support limiting memory usage on a per-application basis, as well as a bunch of other resources (ability to run on particular CPUs, access certain network ports, disk/IO, etc).
You can also prevent applications from stomping on each others' files, with a combination of permissions, chroots and mount namespaces.
This is basically a low-level API for a controller daemon. The daemon knows (via a centralized cluster scheduler) what jobs need to be running on the machine, and how much of each kind of resource they're guaranteed and/or are limited to. lmctfy translates those requirements into kernel calls to set up cgroups that implement the required resource limits/guarantees.
While you could use it for hand administration of a box, or even config-file-based administration of a box, you probably wouldn't want to (lxc may well be more appropriate for that).
You can run many different types of applications on the same host without the risk of one of them utilizing all of the system resources and leaving none for the others.
Finally, it came down to:
"This gives the applications the impression of running exclusively on a machine."
OK but as an outsider that still doesn't tell me what it buys me (or what it buys you, or Google).
(By outsider, I mean I have reasonable ability to administer my own Linux system, but wouldn't trust myself to do so in a production environment... so I'm not up on the latest practices in system administration or especially Google-scale system administration.)
Setting aside whether I need it (I'm pretty sure I don't, so no need to tell me that) I'm really curious what this is good for. Can someone explain it in more lay person's terms? Sounds like applications can still stomp on each others files, and consume memory that then takes away from what's available for other applications, so what is the benefit?
I'm not questioning that there's a benefit, just wondering what it is, and how this is used.