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Recompile again

Started: Wednesday, October 22, 2003 17:19

Finished: Wednesday, October 22, 2003 17:33

I write this rambling as my kernel recompiles yet again.

Yesterday, feeling adventurous, I grabbed the 2.6.0-test8 kernel (there seems to be a lot of that going around these days) and had myself a nice long make config session.

After getting it all compiled, and finding the fix to a minor problem with loading modules, it seemed to work wonderfully. A tad more responsive on the desktop, and smooth as anything.

With everything except kohan, which sort of ran, but gave all sorts of wierd clicks on the sound, and the interface was mighty choppy. How ironic, considering that the reason I decided there was no longer anything to stop me from upgrading was that kohan had purportedly been patched to work with the new kernel series.

Today, I decided to do some more looking. I suspected that perhaps the preempt feature, which I had enabled, might have something to do with it. So I recompiled with preempt off. No luck. Still the same behavior.

On a hunch, I also tried running a couple of my other games. The old Loki version of kohan (which I still say was a much better porting job all around), exhibited the same strange behavior, interestingly enough. Ditto with Call to Power. (Although less pronounced there, due to it not being a real time game, and no music.) However, quake3 works as well as ever.

So it's not just kohan that's affected. Must be something systemic that these games all use. Hmmmmm....

My latest theory? It might be caused by the ALSA driver's OSS emulation. (Up until this new kernel made it as easy as hitting "Y" at the prompt, I had never done anything with alsa on my system.) So now, at this moment, I'm recompiling 2.6.0-test8 with no ALSA. I really hope this fixes the problem, because I really would like to start using the 2.6 kernel full time.

Oh goodie. Looks like it's about done. Here goes....

No good
by Bitscape (2003-10-22 17:39)

Well, even with the old OSS sound drivers, kohan is still all choppy and clickey. Unless there are any other bright ideas, looks like I'll go back to using 2.4, at least whenever I want to play kohan. :(

No problems for me
by Zan Lynx (2003-10-22 21:48)

I'm using the ALSA drivers and not having problems.

Faster machine?

Dual processors?

Gentoo vs Debian?

alsa-lib version?

Who knows?

It's not the alsa drivers
by Bitscape (2003-10-22 22:33)

When I went back to the OSS drivers, the problem was still there. It only happens with kohan and a few other games. Everything else on my system (including sound, opengl, etc) works great. Very strange.

ALSA report
by Jäger (2003-10-23 07:46)

I've been using alsa with 2.4 on Ziyal for ... the forseeable past. (Ever since I decided I really wanted to use my motherboard's built-in sound card, which oss didn't support.) I haven't had any issues with Kohan.

Another thought about clicky sound
by Zan Lynx (2003-10-23 18:04)

Could you try increasing your buffer size? I also saw online a comment suggesting that if you have Option "pci_retry" defined in XF86Config, you should comment it out. I saw another comment talking about PCI bus latency. Read this: Info Play with setpci a bit and see if you can fix it...

Hardware
by Jäger (2003-10-23 21:56)

Bitscape, what hardware sound device are you using? (And did you get any clicking in any other sound-playing application?) What are the odds you have a misconfigured sound options?

All hail the glory of distributed troubleshooting. :)

(For the record, I'm using my on-board VT8233.)

Creative SB Live
by Bitscape (2003-10-23 22:38)

It's a Creative SB Live, but I suspect that my problems are unrelated to the sound hardware or drivers because when I run the game under 2.6, the mouse cursor is also very choppy, and the whole game seems to lag a bit. It's like the scheduler isn't allocating enough CPU cycles to it or something. Very strange.

Yet More Ideas
by Zan Lynx (2003-10-23 23:23)

What is your CPU speed? Jaeger and I are both running systems much faster than yours, I believe.

The 2.6 interactive scheduler detects an interactive process by looking for one that waits on events.

Perhaps on your system, Kohan is never waiting at all, using all the CPU available, and being detected as a lower priority process.

Maybe you could try starting Kohan and renicing it to nice -1 or so...

nice -1
by Bitscape (2003-10-24 00:47)

The nice -1 was a good idea. Unfortunately, that didn't seem to fix it either. It's very strange, because I noticed that when I moved focus away from the kohan game, and into another program or another desktop, the sound got smooth again. But the instant I move it back into kohan, things get all choppy again. Very, very wierd.

I suppose it's possible that it could be because my system isn't fast enough, but that too seems unlikely, given that it works with no noticable lag whatsoever under 2.4. I'm running an Athlon 750. Enough CPU for everything I do, at least up until now. Maybe 2.6 has more stringent requirements though?

For now, I'm content to just go back to 2.4. I'll give 2.6 another run when it comes out of the "test" series. Maybe by then, whatever's causing my problems will be ironed out. (I'd almost be tempted to try to debug it myself, but given that I've never really done any kernel level programming, that sounds rather daunting at the moment.)

Try to figure it out...help everyone!
by Zan Lynx (2003-10-24 10:51)

I think you should try to figure out why. It could help everyone! If you wait for 2.6 to be really out, but haven't tried to fix the problem, it probably won't be fixed.

Just poke at it in any spare time you might have lying around. Heh.

Maybe try playing with oprofile and some of the latency debugging patches.

Run top in batch mode to a file while you try Kohan and look at the priority levels your winex processes are getting.

Spin-waiting
by Jäger (2003-10-24 07:15)

On my system (single-processor Athlon XP 1800+), Kohan sucks all of the available processor in 2.4 and 2.6. I'm hoping it's doing its best to do high-framerate video and not merely spin-waiting.