RE: realtime scheduling problems with 2.4 linux kernel >= 2.4.10

[Ian Collinson <icollinson@imerge.co.uk>]

Andi Kleen wrote:
> Fixing it would require boosting keventd's priority either globally 
> or temporarily. E.g. if the original reporter could put this
> (untested/uncompiled) at the beginning of
kernel/context.c:context_thread():
>
>     current->policy = SCHED_RR;
>     current->rt_priority = 99;
>
> it could fix his problem.

OK, I've tried the above fix on 2.4.17, and it seems to work.  Thanks Andi.
We can now get into the box on a high priority console after provoking a
lockup with a lower priority, CPU hogging realtime process.

Are there any potentially negative consequences of this fix, apart from
those already mentioned?

I certainly vote for this feature being preserved, as it is extremely useful
for debugging realtime priority apps.  FYI, we narrowed it down to breaking
in either 2.4.10-pre11 or pre12. 

Cheers
Ian


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