FreeBSD schedulers (was: Re: FreeBSD)

cpghost at cpghost at
Tue Oct 5 11:24:10 PDT 2004

On Tue, Oct 05, 2004 at 10:59:27AM -0300, Rafa Teixeira wrote:
> I'm from Brasil and I would like to know what kind of scheduling
> FreeBSD uses.

Hi Rafa,

you may want to read Chapter 4 (Process Management), pages 99-108 of:

  The Design and Implementation of the FreeBSD Operating System
  Marshall Kirk McKusick, George V. Neville-Neil
  Addison-Wesley Pearson. ISBN 0-201-70245-2

Fortunately for you, Chapter 4 also happens to be the online demo
chapter for this book. You may find it here:

In a nutshell: FreeBSD (5.x) can use two schedulers, the old SCHED_4BSD
and the new, but still somewhat experimental SCHED_ULE. You can find the
source code here:


If you don't have the sources available, feel free to use cvsweb:


Cordula's Web.

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