Re: 2.2.1 scheduler behavior

Rik van Riel (
Fri, 19 Feb 1999 00:50:36 +0100 (CET)

On 18 Feb 1999, Claude Gamache wrote:

> We have an application made up of 15 processes that interact
> through shared memories and sockets. Each process computes for a
> few milliseconds and then pass its data to the next one (a
> pipeline computation scheme).

> It looks as if the use of the RTC at high frequencies causes the
> Kernel scheduler to be executed more often.

Andrea, Ingo?

> Also, with Kernel 2.2.1, I noticed with that a process has a
> tendency to keep switching from one CPU to another (that process
> being the only one using a noticeable amount of CPU according to
> ps and top). With 2.0.36, it almost never switch CPU ! That could
> explain why performances seems more random with 2.2.1.
> In the scheduler, is the PROC_CHANGE_PENALTY is large enough, is it
> something else ?

It could have something to do with that. Once 2.2.2 comes
out (solving my reboot problems) I'll be working on a new
(or adapted) Linux scheduler that should solve all these
problems and possibly have less overhead than the current

> Is there something to do to adress this ?

Not yet, you'll have to wait for the patch...


Rik -- If a Microsoft product fails, who do you sue?
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