ULE scheduler

Infobox Software
name = ULE scheduler



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author = Jeff Roberson [cite web|url=http://www.freebsd.org/cgi/man.cgi?query=sched_ule&apropos=0&sektion=0&manpath=FreeBSD+7.0-RELEASE&format=html|title=SCHED_ULE(4) man page|accessdate=2008-09-02]
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released = 26 January 2003 [cite web|url=http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/kern/sched_ule.c|title=FreeBSD CVS log retrieved on 27 August 2008]
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frequently updated = yes
programming language = C
operating system = FreeBSD
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license = BSD 2-clause
website =

ULE is a scheduler for the FreeBSD operating system. Currently, it is not the default scheduler, but can be enabled by modifying the kernel configuration. ULE will be the default scheduler for FreeBSD 7.1. [cite web|url=http://www.freebsd.org/releases/7.0R/announce.html|title=FreeBSD 7.0-RELEASE Release Announcement retrieved on 23 June 2008]

History

Originally introduced in FreeBSD version 5 [cite web|url=http://www.usenix.org/event/bsdcon03/tech/full_papers/roberson/roberson.pdf|title=ULE: A Modern Scheduler for FreeBSD retrieved on 23 June 2008] , it has been disabled by default in favor of the traditional BSD scheduler. The default BSD scheduler does not make full use of SMP or SMT, which grows increasingly important in modern computing environments.

General

Making better use of SMP and SMT environments is the primary goal of the ULE project. It is intended to be effective in improving performance in both uniprocessor and multiprocessor environments [cite web|url=http://www.freebsd.org/releases/7.0R/relnotes.html|title=FreeBSD 7.0-RELEASE Release Notes retrieved on 23 June 2008] , as well as improving interactive response under heavy load [cite web|url=http://jeffr-tech.livejournal.com/3729.html|title=ULE 2.0|accessdate=2008-09-02|author=Jeff Roberson] . There has been some speculation that Mac OS X v10.6 will use or contain code from the ULE scheduler [cite web|url=http://neosmart.net/blog/2008/os-x-snow-leopard-to-use-ule-scheduler/|title=OS X Snow Leopard to Use ULE Scheduler? retrieved 1 July 2008] .

References