> do we need to take into account filterEfficiency?
I don't think so but I will look at it.

> do we need to convert to int to be on the safe side?
ceil is converting to int.

> Why do we need to count the number of previous jobs? I don't think this is actually used in the current job splitting. Is it? Is this just an estimate or some statistics?
I think it is used to create lfn it is used as post fix for file name. (But I need to check on that too)