Native preemption is the culprit [was Re: today's CURRENT lockups]

[Thorsten Greiner]

* Robert Watson <rwatson at freebsd.org> [2004-07-06 08:21]:
> The patch below appears to (brute force) eliminate the crash/hang I'm
> experiencing with SCHED_ULE in the post-preemption universe.  However, I
> was experiencing it only in the SMP case, not UP, so it could be I'm just
> not triggering it timing-wise.  This would be a temporary fix until jhb is
> online again post-USENIX to take a look, assuming this works around the
> problem for people other than me.

It does work here (as did backing out the native preemption stuff).

> Note that this is probably damaging to interrupt processing latency.

I have not observed anything unusual with this patch. There are
seemingly no increases of build times for my projects and I did not
experience any interactivity glitches (no jumpy mouse or the like).

Regards
        -Thorsten

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