This paper by researchers at USENIX tackles the differences between FreeBSD ULE and Linux CFS. ULE is the default scheduler for FreeBSD, and CFS is the default scheduler for Linux. See the link provided by to view the full document.

We compare ULE and CFS in otherwise iden-
tical circumstances. We have ported ULE to Linux, and
use it to schedule all threads that are normally scheduled
by CFS. We compare the performance of a large suite
of applications on the modified kernel running ULE and
on the standard Linux kernel running CFS. The observed
performance differences are solely the result of schedul-
ing decisions, and do not reflect differences in other sub-
systems between FreeBSD and Linux

The Battle of the Schedulers: FreeBSD ULE vs. Linux CFS: