Re: Scheduling in Kernel 2.2

Artur Skawina (skawina@geocities.com)
Fri, 03 Sep 1999 15:03:26 +0200

Christoph Pleger wrote:
>
> What has happened with the scheduling under Kernel 2.2?
>
> I had compiled the following program under Kernel 2.0. The program - as intended
> - switched the context between two processes:

> After switching to Kernel 2.2 the program was recompiled. When I let it run
> now, the server-process stays in its endless-loop and the client-process does
> not print anything. What can be the reason for that? Was the scheduling changed
> in the kernel?

yep, sched_yield() is broken for RT tasks. (this is true for 2.3 too;
i have a patch that makes it work, but there's still one more issue
i'll have to look at (code messing directly with scheduler internals;
eg there are places in kernel that assume 'policy |= SCHED_YIELD;' will
cause SCHED_OTHER tasks to run even when current->policy==SCHED_(FF|RR)).

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