所以到底是什么呀？(′･_･`)

The multiplier 4 applies only to utility files used in releases prior to SAS 9, when PROC SORT needs to use disk space in order to sort the data. For in-memory sorting and sorting with SAS 9 and later, the multiplier is 2 or less.
Threaded processing takes advantage of multiple CPUs by executing multiple threads in parallel (parallel processing). Threaded procedures are completed in less real time than if each task were handled sequentially, although the CPU time is generally increased.  
When a threaded sort is used, the observations in the input data set are divided into equal temporary subsets, based on how many processors are allocated to the SORT procedure. Each subset is then sorted on a different processor. The sorted subsets are then interleaved to recreate the sorted version of the input data set.

sas adv prep