Ubuntu – How to one restrict the number of CPU cores each user can use

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We have a computer whose CPU has 32 cores and it's going to be used for running programs by a few different users. Is there any way to restrict the number of cores each user can use at any time so that one user will not monopolize all the CPU power?

Best Answer

While this is possible, it is complicated and almost certainly a bad idea. If only one user is using the machine at the moment, restricting them to N cores is a waste of resources. A far better approach would be to run everything with nice:

NAME
       nice - run a program with modified scheduling priority

SYNOPSIS
       nice [OPTION] [COMMAND [ARG]...]

DESCRIPTION
       Run  COMMAND  with an adjusted niceness, which affects process scheduling.  With
       no COMMAND, print the current niceness.  Niceness values range  from  -20  (most
       favorable to the process) to 19 (least favorable to the process).

This is a great tool that sets the priority of a process. So if only one user is running something, they'll get as much CPU time as they need, but if someone else launches their own (also niced) job, they will be nice and share with each other. That way, if your users all launch commands with nice 10 command, nobody will be hogging resources (and nobody will bring the server to its knees).

Note that a high nice value means a low priority. This is a measure of how nice we should be and the nicer we are, the more we share.

Also note that this will not help manage memory allocation, it only affectes CPU scheduling. So if multiple users launch multiple memory-intensive processes, you will still have a problem. If that's an issue, you should look into proper queuing systems such as torque.

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