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
-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