Question

Compare and contrast the evolution of the default BSD/FreeBSD and Linux schedulers.

Answer

Resources

I found some resources, which might be useful to answer this question. As far as I know, FreeBSD uses a Multilevel feeback queue and Linux uses in the current version the completly fair scheduler.
-Some text about FreeBSD-scheduling http://www.informit.com/articles/article.aspx?p=366888&seqNum=4
-ULE Thread Scheduler: http://www.scribd.com/doc/3299978/ULE-Thread-Scheduler-for-FreeBSD
-Completly Fair Scheduler: http://people.redhat.com/mingo/cfs-scheduler/sched-design-CFS.txt
-Brain Fuck Scheduler: http://en.wikipedia.org/wiki/Brain_Fuck_Scheduler
-Sebastian

Also found a nice link with regards to the new Linux Scheduler for those interested: http://www.ibm.com/developerworks/linux/library/l-scheduler/
It is also referred to as the O(1) scheduler in algorithmic terms (CFS is O(log(n)) scheduler). Both have been in development by Ingo Molnár. -Abhinav

Some more resources;
http://www.ibm.com/developerworks/linux/library/l-completely-fair-scheduler/index.html (includes history of Linux scheduler from 1.2 to 2.6)
http://my.opera.com/blu3c4t/blog/show.dml/1531517
-Wes

Information on changes to the O(1) scheduler:
"Linux Kernel Documentation"
http://www.mjmwired.net/kernel/Documentation/scheduler/sched-nice-design.txt

General information on Linux Job Scheduling:
"Linux Job Scheduling | Linux Journal"
http://www.linuxjournal.com/article/4087

Scheduling on multi-core Linux machines:
"Node affine NUMA scheduler for Linux"
http://home.arcor.de/efocht/sched/

More on Linux process scheduling:
"Understanding the Linux kernel"
http://oreilly.com/catalog/linuxkernel/chapter/ch10.html

FreeBSD thread scheduling:
"InformIT: FreeBSD Process Management"
http://www.informit.com/articles/article.aspx?p=366888&seqNum=4
- Austin Bondio