Re: printks in the scheduler freeze during scripts

From: Michael S. Zick (
Date: Fri Jun 28 2002 - 06:56:15 EST

On Thursday 27 June 2002 09:03 am, anton wilson wrote:
> I'm running linux 2.4.17 and Redhat 7.2 with the preemptive and low latency
> patches, and whenever I stick printks in the scheduler(void) my system
> freezes somewhere after it tries to load the system font. Where it stops
> seems to be random. I can only run under single user mode without my system
> freezing. Does anyone have any clues why? Or any better ways to go about
> tracking the scheduling of processes in the scheduler?

Something I have used in my testing:

Add, in the task structure:

task_t *sched_from;

In schedule, prior to context_switch:

next->sched_from = prior; /* at this point still == get_current ()*/

Somewhere else (so you don't inadvertantly side-effect to death schedule()):

Follow the back-link and printk whatever for the task that you are interested
in, being careful not to reference task structures that no longer exist.

> Anton
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