Hello!

>>> >> There are a whole host of things you can do to make it better. First
>>> >> of all, when the errors started, had you made any changes to your
>>> >> machine?
>> >
>> > I try as much as I can to not do any changes to the system, but there
>> > were some updates via apt-get.
> 
> Specifically, which updates did you get?

Unfortunately I didn't noticed I had a problem until days
later. So I can't really tell what was updated. I now that
powersaved was updated recently, but unsure exactly when.

>>> >> There are a couple of things that are known to exacerbate this issue:
>>> >> enabling SMP on a HyperThreading or Multiple-Processors machine, raid
>>> >> arrays, cpu frequency scaling, interrupt conflicts, bad PVR cards,
>>> >> and bad RAM.
>> >
>> > I do have powernow-k8 installed, but it's been there all the time  
>> > without
>> > causing any noticable trouble. I also have powersaved installed but  
>> > haven't
>> > had the time to configure it.
> 
> There's an easy way to disable cpu frequency scaling, but you'll have  
> to make sure that the powersave daemon is not running (kill it or  
> disable it from running). If you would rather not have to recompile  
> your kernel, you can just execute the following command every time  
> you boot up the computer:
> 
> sudo echo performance > /sys/devices/system/cpu/cpu0/cpufreq/ 
> scaling_governor

OK, I will look in to this. Right now it is set to:

htpc:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
ondemand

>> > In a desperate attempt to fix the problem I compiled the ivtv  
>> > source and it
>> > seems it installed drivers not needed by my system. I only use a  
>> > PVR-150.
>> > Is this output indicating something wrong? Could I remove some?
>> >
>> > htpc:~# lsmod | grep ivtv
>> > <snip>
> 
> You have not done anything wrong - all of these modules are necessary!

OK, that sound good.

>>> >> To better diagnose this issue, could you provide output from /proc/
>>> >> interrupts and lspci -v?
>> >
>> > htpc:~# cat /proc/interrupts
>> > <snip>
>> > htpc:~# lspci -v
>> > <snip>
> 
> Well, at least your ivtv card is not sharing its IRQ. But it is the  
> lowest IRQ, and your Serial ATA device has a high number of  
> interrupts, which could be the culprit... do you have some kind of  
> RAID or LVM array set up with multiple hard drives?

No RAID but I use LVM and have not seen these problem since I
built my system for over 6 month.

> Since it seems as though this was just an issue with upgrading your  
> OS, I would try disabling the cpu frequency scaling / powersave  
> daemon first, as that is likely the culprit.

I have done some recording two days in a row and all seems to
work fine. No DMA errors in the log. I don't have mythfrontend
running. Only the backend.

I had a feeling that the problem occured only when the frontend
was running. I have to test this before I can draw any conclusions.

> If that does not fix your problem, you can try tweaking your PCI  
> latency timings, as some people have had luck with this in the past.  
> There's a great article on how to do this at Gentoo's site:
> 
> http://www.gentoo.org/doc/en/articles/hardware-stability- 
> p2.xml#doc_chap3
> 
> To adapt this guide for ivtv, I would set all your PCI devices (even  
> audio) to a setting of 'b0' then set the ivtv card to 'ff'.
> 
> Hope this helps!

Thanks for all you help!

/Peter

>> > On Nov 21, 2006, at 3:18 PM, Peter Carlsson wrote:
>> >
>>> >> Hello!
>>> >>
>>> >> A few days ago I had problems with the well known DMA errors
>>> >> while running kernel 2.6.16 and ivtv 0.6.3.
>>> >>
>>> >> I have now upgraded my Debian system to kernel 2.6.18 and
>>> >> ivtv 0.8.0 with the hope that the problems were fixed.
>>> >>
>>> >> Yesterday I successfully recorded a one hour show but today
>>> >> the DMA error seems to still be here.
>>> >>
>>> >> Any suggestions are welcome!
>>> >>
>>> >> <snip>
> 

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