So far, the backend seems to be stable in uniprocessor mode. I'm still not too happy, since one of the tuner cards (always seems to be the one in the bottom-most PCI slot, no matter which of the cards I put there) tends to stop working on reboots. A really cold boot (switching the power off from PSU for some time) seems to help. In general, I try to avoid booting, so I don't have statistically significant data on this .

As I mentioned earlier, I won't be home next week, so I probably won't post any updates here either. When I get back, I will probably buy Club 3D 8400GS 256MB GDDR2 PCI-E (since this seems to available for reasonable price of 30 euros) and see, if it perhaps solves all my problems. That is, unless someone has a better suggestion.

I was somewhat disappointed to learn that there are no cheap cards with dual DVI-connectors or dual link DVI connector for that matter. Not that I need those with Myth (at least for now), but since those features seems to come for free in more expensive cards, I had hoped to find them from cheaper models also.

I'll be posting again in about a week to tell whether GeForce helped or not.

-JLarja

Hello again

I don't have very much to report yet, but since I'm going to be away for another week, I decided to share what little news I have.

I bought the 8400GS and replaced X800XL with it. I haven't had the time and energy to re-install Knoppmyth yet so results so far are perhaps not yet final. Frontend is much more stable. It crashes with some settings (for example OpenGL renderer, OSD and vsync), but I haven't really tested what are the problematic ones. Slim and high quality profiles seem to work and CPU load is low. Still no HDTV playback though.

Last time I wrote that uniprocessor mode seemed to solve backend stability problems. I was unfortunately wrong. Backend crashed once last week. It also crashed once using 8400GS. I am now testing in multiprocessor mode and backend has crashes once with it too. Two of the crashes were "clean" (backend process ended), once I had to kill the process manually. There also seems to be some problems with encrypted channels and live TV (only one of the tuners has encryption module), which I hadn't noticed before. Since I rarely watch live TV, these problems probably aren't new.

One of the tuner cards still disappears during bootup every now and then. The clash seems to be either with motherboard or with the other tuners. I've done some googling on nForce 4 and Asus A8N SLI and apparently there have been some trouble with Linux. Moreover, the problems seems to depend on BIOS version (which has been newest whole time), so I wouldn't be too suprised, if some are yet to be solved.

I will probably do a re-install once more, if just to get TV-out working (that's probably easiest way), but I don't think that will help with backend stability problems. There were some with R5F27 too as I told. Perhaps those will get solved with some future kernel or MythTV update.

-JLarja

My old motherboard was giving me problems. I modified the lilo conf with suggestions from the following link. Put in append line.
http://www.knoppix.net/wiki/Cheat_Codes
See the part with

Ok, this will probably be my last post on this subject. 8400 did help with frontend stability problems (it still crashes sometimes but that seems to be connected to backend crashes), but both mythtv-setup and backend are like they used to be. Perhaps mythtv-setup is not quite as bad, but tuning the channels still takes several crashes. Backend crashes every now and then. It seems to be a bit more stable in uniprocessor mode, but it would probably take weeks to collect statistically relevant data on subject.

So, the problem seems to be also with motherboard or tuners. Perhaps next version of KnoppMyth, with updated Linux kernel, will work better. If not, I will probably build a new box sooner rather than later (not too soon anyway, think 2010 or something. Later would be something like when the motherboard or processor blows up ). Anyway, I don't think I am going to spend any more time on this. The box works better than my old PVR. I can live with that.

By the way, I didn't get the TV-out working. Since it would only be a convenience for a while (I'm planning on getting a new TV, which would obviously have an HDMI connector), I didn't want to spend too much time on it. I just tried nvidia-settings and when that didn't work, gave up.



Thanks for the suggestion but this didn't help. IRQ mappings were the same whether I used pci=biosirq or not. Using nosmp disables APIC, which of course results in completely different IRQ handling. I don't know whether better stability in uniprocessor mode (if there even is any) is due to legacy IRQ handler or solved SMP issues.

(And yes, I have tried noapic in lilo.conf, but that doesn't do anything (still uses APIC). Noapic and acpi=off doesn't boot. When I installed with noapic and acpi=off I got uniprocessor installation which still had stability issues, but that was before GeForce.)

So thank you everybody for your suggestions. Next time I will stick to the tier 1 hardware, if possible .

The bottom PCI slot usually shares an IRQ with one of the other
slots. If you can, don't put any cards there. If this is not
possible, put a card there that does not need an IRQ. If that
is not possible, remove a card for a test for a while.

Well, there are three PCI slots and I have three tuner cards, so using only two would be very unsatisfactory solution. According to /proc/interrupts tuners don't share IRQ (not in APIC or legacy mode) between them, but two of the cards share IRQs with other devices (on-board Ethernet and display controller in apic mode. I don't recall details but there is some sharing in legacy mode too).

It is pretty hard for me to test with less than three tuners, since backend crashes aren't that common. For example, between evening of 3th and evening of 9th of September there were no crashes but since 8 pm yesterday (9th) backend has crashes four times. I actually need to record from three different transports every now and then, so I really wouldn't care to test this. Getting any useful results could take weeks. Even if using just two cards would work, I would have to buy some new hardware to resolve the problem, which I could, of course, do any time already .

Anyway, I earlier tested with mythtv-setup channel tuning with different number and placement of cards, but that didn't help. If the tuning problems and occasional crashes are caused by the same problem, then removing one or two cards won't help.

P.s. I've been having trouble posting to this forum. Been trying different browsers and deleting cookies, but nothing seems to help. I always get "Invalid Session. Please resubmit the form" message. I hope I can finally sent this message.

Edit: \o/ Finally .
-JLarja

I was having unexplained crashes while trying to scan DVB-S channels in mythtv-setup as the original poster mentioned. Once the channel would finally scan in (after trying it about 20 times), the frontend/backend would always get the channel with no problems. It was always the mythtv-setup that was crashing.

Anyway, I installed the "taskset" command for the command line.


Then, run mythtv-setup in single processor mode


Has scanned without crashing. It did jack up the mythtv-setup on screen display a little....like the scanning % meter window was shrunk way down, but it still worked.

Now, if it would just correctly scan in Setanta....we'd be all set.

_________________
Proud member of the Loyal Brotherhood of Snipe Hunters - Local 414

I've actually installed taskset myself and have been running backend in single CPU mode for several weeks now. Unfortunately it doesn't seem to help. Backend crashes every now and then (as does the frontend, but that usually happens when I am doing something stressful with it).

Scanning % meter in mythtv-setup has been broken randomly regardless of multiprocessing, display mode, graphics card or anything else. It seems (but again, I don't have statistically significant data) that it is more often broken in low resolution modes. I haven't mentioned this earlier, since it is totally non-issue compared to other problems.

Anyway, thanks for the suggestion. Unfortunately it seems that going to single processor mode only solves big problems, not the small but annoying ones.

-JLarja