Re: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.25-1

From: Shane Shrybman
Date: Fri Nov 12 2004 - 15:22:10 EST

On Fri, 2004-11-12 at 13:23, Mark_H_Johnson@xxxxxxxxxxxx wrote:
> >Typical example of the error message:
> >
> >kernel: hde: dma_timer_expiry: dma status == 0x24
> >kernel: ALSA sound/core/pcm_native.c:1424: playback drain error (DMA or
> IRQ trouble?)
> >kernel: PDC202XX: Primary channel reset.
> >kernel: hde: DMA interrupt recovery
> >kernel: hde: lost interrupt
> >
> >This was on a Promise TX2 133 ide card with one IDE disk. The problem
> >would show itself if using the RT patches and APIC. But the problem seems
> >to have been resolved now.
> I had errors like that one when the IDE IRQ was at a priority less than
> the real time task. Since then, I run with all the IRQ's at max RT priority
> and will continue to do so until I get a better assessment of what my real
> application (not these audio tests...) needs for IRQ priorities.

Ok, I wasn't comparing apples to apples. I forgot I had to remove the sb live
card from this machine a few days ago. So the hardware config wasn't exactly
the same. I have reinstalled the sb live card now and I am retesting on 0.7.25.
The sb live shares an irq with ide2(promise card)

0: 835791 IO-APIC-edge timer 0/35791
1: 2207 IO-APIC-edge i8042 1/2207
8: 4 IO-APIC-edge rtc 0/4
9: 0 IO-APIC-level acpi 0/0
15: 11 IO-APIC-edge ide1 1/9
16: 70527 IO-APIC-level ide2, EMU10K1 0/70527
17: 1093 IO-APIC-level eth0 0/1092
18: 37440 IO-APIC-level bttv0, Bt87x audio 173/37439
19: 39147 IO-APIC-level aic7xxx, ivtv0 340/39143
21: 25091 IO-APIC-level uhci_hcd, uhci_hcd, uhci_hcd, uhci_hcd 52/25091
22: 85425 IO-APIC-level VIA8237 494/71991
NMI: 836519
LOC: 836340
ERR: 0
MIS: 1

With the sb live card back in use the system has hung once with the sound looping.
It hung after I started playing a video in a second instance of the mythfrontend
application. I had the nmi_watchdog on and netconsole logging to another machine
but there was nothing in the logs.

I have rebooted and I am trying to verify the dma_timer_expiry issue is still gone
with the sb live in use.

> This may have been fixed as a side effect of Ingo setting the IRQ threads
> at
> RT priorities in the 40's.

I had originally thought this might be the cause as well so I jacked
ide2 priority but it didn't help. However it does share the irq so maybe
that is a factor here.

> --Mark H Johnson
> <mailto:Mark_H_Johnson@xxxxxxxxxxxx>


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