Five Steps Nicer

Two CPU-bound threads, one core, nothing else runnable. Thread A runs at nice 0, thread B at nice 5. sched(7) states that each unit of difference in nice value changes the scheduler's favour by a factor of 1.25.

Roughly what share of the core does thread B get?

A

About 75%

B

About 5%

C

About 25%

D

About 50%, because nice only breaks ties when two threads are otherwise equal