The effect of nice value in CFS scheduler

[Anh Le]

Hi everyone,

I'm studying the CFS scheduler. I'm using ubuntu 13.10 and I assume that
it's using CFS in it kernel.

I try to see the effect of nice value by running 2 instances of the same
program (just a while loop of calculations), putting them on the same CPU
and setting different nice values to them (one is 19 and one is -20). I
include in the program some printf to see how much it has executed.

According to my understanding, the process with the small nice value should
get more processor time than the one with the big value. However they seem
to be on par with each other (they execute approximately the same number of
loops in the same duration), so I'm really confused.

I'd appreciate any help.
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