which means these lines (CFS)

Hello everyone! Learning scheduler CFS. It was not clear a few lines of help -  http://lxr.free-electrons.com/source/kernel/sched/fair.c Question: what means  granularity = 750000ULL; in line 91 -  http://lxr.free-electrons.com/source/kernel/sched/fair.c#L91 and  what means latency this line 50 - http://lxr.free-electrons.com/source/kernel/sched/fair.c#L50 I ask because I rarely meet such words, and only while starting to learn the source code Thank you all for your attention!