[linux-dvb] Problems with APIC/LAPIC (was: Re: Problems with SMP (i.e. dualcore) system: dvb-ttpci: warning: timeout waiting in LoadBitmap)

Markus Rechberger mrechberger at gmail.com
Mon Aug 6 22:37:47 CEST 2007


On 8/6/07, Sven Mueller <linux-dvb at incase.de> wrote:
> Oliver Endriss wrote on 05/08/2007 06:14:
> > Sven Mueller wrote:
> >> Oliver Endriss wrote on 01/08/2007 00:27:
> >>> Sven Mueller wrote:
> >>>> Hi.
> >>>>
> >>>> I don't know which hardware interrupts those are mapped from/to and
> >>>> currently don't know how to find out.
> >>>>
> >>>> If you need any further data to give a helpful answer, don't hesitate
> to
> >>>> ask.
> >>> Which firmware are you using?
> >> Most recent AFAICT (261f).
> >
> > Nope, the most recent firmware is
> > http://linuxtv.org/downloads/firmware/dvb-ttpci-01.fw-2622
>
> I tested that one as well, but I wasn't sure wether it was actually
> newer, since the downloads I could find on the Technotrend pages only
> had 261f IIRC.
>
> >>> Does the VDR recover if you wait some time (1 or 2 minutes) before you
> >>> press the next key?
> >> Sometimes (if I interpret things correctly though, this is due to an
> >> internal watchdog in VDR triggering a restart, which now, on my system,
> >> includes module unload/reload due to my problems).
> >
> > With recent firmware VDR should recover _without_ emergency exit.
>
> It might do, I currently don't have much time to do tests (and, to be
> honest: not much inclination to do tests just to find out if and how the
> system recovers after a failure).
>
> >>> You might also try whether this driver improves things:
> >>> http://linuxtv.org/hg/~endriss/v4l-dvb-av7110-refactoring/
> >> Will take a look into that later once I find some time.
> >>
> >> One think fixed the problem for me, for now though:
> >> noapic nolapic
> >> on the kernel commandline (grub).
> >
> > Are you sure that this did not disable SMP?
>
> Hmm, /proc/cpuinfo reports two CPUs and I had two processes (just some
> Perl processes with while loops counting up until a certain file was
> created) for which top reported near 100% CPU usage. So I'm quite
> certain it didn't disable SMP.
>
> >> However the system runs stable in every other aspect, so it seems to me
> >> that enabling apic/lapic does something which the dvb_ttpci driver
> >> doesn't handle properly on SMP systems.
> >
> > There is no special handling for SMP or non-SMP systems.
> > Of course there might be a bug which will only show up with SMP. :-(
>
> Right, that is what I thought of first, too, but as said I'm almost 100%
> sure I now have a stable system running with SMP (though without
> APIC/LAPIC). So the bug (which I think is somewhere in dvb_ttpci) seems
> to be triggered by some LAPIC or APIC specific code somewhere in the
> kernel (i.e. not necessarily in the dvb_ttpci driver).
>

can you submit some logs?

cat /proc/interrupts
cat /proc/cpuinfo

are you sure the irqs are balanced over the cores?

Markus



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