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So far we configured limits on the usage of operating syste resources and the CPU. Let´s get back to the class room example used before. A different course at the unseen university is "Memory Management for beginners". And at start our students have problem with severe memory leaks. It would be useful to impose resource management to the memory management.

Okay, but your system wasn´t purchased for students at night. You´ve bought it for computational science at night. The Large Hadron Collider project spend 75% of the costs, and the Small Hadron Collider project spend 25%. Thus the compute power should be distributed in a similar manner.

The kernel of an operating system provides a huge amount of resources to the processes running on it. Such resources are file descriptors, shared memory segments or the process tables. Albeit it´s hard to fill up this resources with modern operating systems it´s not impossible. When a resource is consumed by a single malicous or erronous application, all other can´t run as well when they need more resources from the operating system.

Even when you never heard of constructs like tasks and projects you already use them, as there are a few projects installed per default. For example whenever you log into your system as a regular user, all you do is part of the project default because your user is member of this project:

# su jmoekamp
# id -p
uid=100(jmoekamp) gid=1(other) projid=3(default)