When I make a CPU-intensive process lowest priority (niceness of 19), it seems the amount of real memory consumption goes up. Perhaps this has other causes.

But, can making CPU-intensive processes lowest priority have adverse effects?


Reducing the priority of a process will only make it run for longer. So the only possible side effects would be:

  • Its memory usage being assigned longer because it runs slower, and since it remains active, it will remain in active memory or cause paging (swap in and out). This is seldom a problem unless you're tight on available memory.
  • If the process uses locks such as record or file locks and the same resources are used by another process, then the two processes could slow each other down. Although it's a fairly uncommon situation, if that applies to your case, reducing the priority could drastically slow down the system.

Changing the priority/niceness only changes the process's time quantum.

From Understanding the Linux Kernel (3rd ed.) §

Table 7-2. Typical priority values for a conventional process

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