Subject: [linux-audio-dev] voluntary-preempt-2.6.x-Q5..R6 SMP/HT trouble (was: realtime-lsm in the kernel)
From: Rui Nuno Capela (rncbc_AT_rncbc.org)
Date: Wed Sep 08 2004 - 02:44:51 EEST
Lee,
>>
>> I'm having some trouble with latest VP patches on my P4 HT/SMP box. The
>> trouble is that since Q5 that I can't get my machine to boot reliably,
>> if at all. It goes almost all through the init scripts to drop dead on
>> the beach, so to speak. It just freezes completely somewhere before the
>> login prompts.
>>
>> This only happens if the kernel is configured for SMP/SMT
>> (HyperThreading). The very same kernel configured and built for UP
>> boots and runs fine. As I said before this was introduced on the Q5
>> patch, and the same showstopper is present on latest R6. Only with Q3
>> I'm still happy, altought only with softirq-preempt=0 AND
>> hardirq-preempt=0.
>>
>> The "offending" box is a SUSE 9.1 based one, P4 2.80C HT on a ASUS
>> P4P800 mobo, 1GB DDR.
>>
>
> I posted the above report to LKML and cc'ed you and Ingo. None of the
> LKML testers are reporting this problem, it sounds very similar to the
> problems others have had with SMP/HT but those were thought to all be
> solved.
>
Thanks. Yes I was pretty excited with those reports too (I've been lurking
on LKML :), but I just seem to be unlucky. That's why I've been trying one
by one of the patches, from Q5 to R6 and tweaking the available options as
much as I know and time permitted.
OK, could just someone with a P4 HT/SMP box hand me their woring kernel
.config file for me to try? That could be a good starting point, if not a
plain baseline.
>
> Has any version worked with softirq or hardirq preemption enabled? What
> are the symptoms if you boot Q3 with either of the above enabled?
>
On this box in question, softirq and hardirq-preempt options had NEVER
lead to a stable SMP/HT system, ever since my first rehearsal with VP,
which I think was around O3. UP is quite different, it works and always
worked, as advertised :) FWIW, R6 is pumping hard on my laptop :)
Q3-SMP doesn't pass the KDE 3.3 startup splash if I set softirq=1 or
hardirq=1. The system just hangs. I still keep softirq-preempt=0 and
hardirq-preempt=0 as my Q3-SMP kernel bootloader parameters though.
Hope this gets cleared out. All I can do is offering my best efforts to
dig this out, provided someone give me some hunch ;)
Thanks again.
-- rncbc aka Rui Nuno Capela rncbc_AT_rncbc.org
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