Re: scheduling

Alexander Kjeldaas (
Fri, 1 May 1998 18:30:42 +0200

On Fri, May 01, 1998 at 10:14:48AM -0400, Andrew J. Anderson wrote:
> > Perhaps we could have 3 levels of the "QNX scheduler" and run
> > the normal timesharing scheduler within each of those. If there
> > isn't a standard name for it already, I suggest "priority bands".
> I have been working on a feedback multilevel scheduler with 40 levels to
> make it easier to incorporate with the kernel and user utilities. I
> haven't touched it for a while, but it was starting to work, but kept
> running into problems remoing things from the run queue. I had ambitions
> at one time of making it a tunable scheduler, but I'm still focusing on
> stability for now. I can probably generate some patches against 2.0.33 if
> there's interest.

If you are thinking of a new scheduler, would it be possible to design
one that doesn't have to traverse the task_list as much as the current
one? The current scheduler is O(n) in the number of processes. A fix
to that would help the kernel ultimately end up being independent of
the number of processes.


 Alexander Kjeldaas, Guardian Networks AS, Trondheim, Norway

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