Stuttering and Lags. Is it my System?

[Taki]

Hi there.

I really like your Game. Greetz from Germany. I enjoyed the COmbat mission Campaign and im stick to the New COmbat Mission like Game you are working on.

As i played i regognized the Armour Penetrating Sound is the same as in Combat Mission Nice!

But here is my Problem. I joined the Public Testing Server. I can tune down the Grapic Settings to a Minimum but i have Realy Hard Lags and Frames are going down to 0 sometimes. I have played otehr Games with a Ping of +200 but i guess there is another Problem.

Question: Is anyone facing the Same Problem? Is it from the Server Site and a Ping Problem or got the Demo some Problems with my Computer?

I really enjoy the Game and its "Real Balistics" but its unplayable if it keeps like that...

Need help.

Greetz from

Football Germany !

[aittam]

ping may be an issue here, what type of machine are you using?

[Paul Snively]

My one real critique of the game's underlying technology is (making an educated guess here) its network code. In my experience, hard stops sometimes lasting seconds, but typically around 1 second, occur when "something significant" happens, e.g. someone gets a kill. My theory, which could be all wet, is that these "significant events" are being communicated in such a way that no game progress is made until all players have been notified of the kill and acknowledged it, which is deadly for throughput.

I see that DropTeam is using SDL.net, but I wonder what aspects of it it's using, and how. I'd like to suggest that the dev team investigate Spread as a possible alternative networking framework with many features that make it attractive for game development. Of course, I'm also happy to discuss the issues further, as a former game developer who maintains an intense interest in distributed computing.

[ClaytoniousRex]

Experiencing long lags or pauses during play (except for in the first 30 seconds or so) is not normal.

There is one significant client-side bug right now that will intermittently cause long pauses of a few seconds but this typically happens, at most, one or two or maybe three times in a game. It often doesn't happen at all during an entire game. The pause will typically last for 2 to 5 seconds and then go away. This bug is pretty benign and doesn't sound like what you guys are describing here.

Outside of that one current issue, you definitely should not be seeing long lags or pauses. There is no pause while synchronizing clients or anything like that (you can pull the network cable off of a client machine and everyone else will keep playing fine).

Paul, are you pretty sure you're seeing lags as often as once per kill? In a typical game, that must mean you're getting hit with a lag every few seconds - is that right? This is truly bad, if so. Do you have similar pauses while playing standalone? The first step for you both you and Taki is to diagnose the problem as either network lag or something on the client-side that is pausing. The best way to know the difference is this: network lag causes objects to drift out of position or sometimes even disappear but the game continues running smoothly (camera rotating and mvoement for example are unaffected). A client-side lag causes everything to literally freeze - the camera stops moving, the graphics stop updating (like you're looking at a still image of the last frame that rendered), etc. Client-side pauses like this have a variety of causes but usually have to do with files loading from disk or with textures being uploaded into video memory and compressed. Both of these common cases happen mostly when texture cacheing is off.

So let me know if your pausing seems to be network or client-side and we'll dig deeper from there.

[aittam]

Paul just stop killing people

[Paul Snively]

I've obviously given the wrong impression: I was using a successful kill as a sometime-example of when these lengthy pauses occur. But from your description, Clay, what I'm seeing are what you're calling "client pauses" as opposed to "network pauses," because the whole "world" really does grind to a halt, vs. seeing "leaping tanks." Having said that, if network latency is resulting in "leaping tanks," there are still opportunities to improve your netcode by doing more asynchronously, keeping the local objects interacting, and using various predictive and dead-reckoning algorithms to reconcile the local view of the world with the global view of the world. But now I'm badly off-topic verging on being offensive to a guy who's written a great game.

Let me try dropping some of my settings (although I'm on a 1.67 GHz PowerBook with the BTO 128M VRAM option) and see if that helps things.

[Paul Snively]

Update: dropping all quality settings to half and resolution to 800 x 600 solves 99% of what I was seeing... which to me suggests rather strongly one of two things:

1) DropTeam is CPU-bound and my 1.67GHz G4 needs to crunch less data, which is helped both by the quality and resolution drop.

2) DropTeam is texture-cache bound, and so was primarily helped by the resolution drop.

I would love to hear about other people's experiences with fiddling with their settings, but regardless, I have to say I'm surprised: I'm accustomed to playing, e.g. UT2004 at 1280 x 854 with all the settings at full-on gorgeous. OTOH, I know you guys are doing some serious simulation number-crunching, and UT2004 isn't doing anything with pixel/vertex shaders, soooooo... not a fair comparison.

Other settings comments, anyone?

[ClaytoniousRex]

But now I'm badly off-topic verging on being offensive to a guy who's written a great game.

Not at all. It's always fun to talk about ideas and poke and prod and explore for better ways to do things. DropTeam does, in fact, do a totally asynchronous simulation on the client-side, using dead-reckoning based on the last known orientation and derivative of orientation of objects from the server. So when there's lag, you don't see "leaping" tanks, you see "drifting tanks" - they will continue along their last known linear and angular accelerations until you hear from the server again. If you want to get downright geeky and technical about the gritty details then please feel free to email me directly because we could probably talk about it for hours and bore everyone else on this forum to tears in the process. Or, if you prefer the forum and don't care if others get bored, then that works, too.

dropping all quality settings to half and resolution to 800 x 600 solves 99% of what I was seeing

When you had all of the settings on high, did that include HDR? HDR, out of everything else, is far and away the most screen resolution dependent option. HDR does a lot of image post-processing to create glow and halo effects. This means there is work going on for each pixel in the image. Higher resolutions will have a severe impact here. If you did have HDR on originally, try turning everything ELSE back up (including resolution) but leaving HDR off. How much of a difference does it make?

That was just my first thought; it will be interesting to hear what kind of impact different settings have for different users with various hardware.

[Paul Snively]

Thanks for the kind words, Clay. Sometime we'll have to talk game dev over the poison of your choice.

I had tried HDR... and it rendered the game totally unplayable (read: seconds per frame vs. frames per second) on my 15" PowerBook with the 128M VRAM option. So you can safely assume that I always have HDR off.

The next thing I tried was cranking up all options but the resolution, leaving it at 800 x 600. The result, in terms of performance, was subjectively indistinguishable from having the options at half, except, of course, the visual results were vastly better (in particular, there was much less annoying "popping" of the terrain as the CLOD stuff did its thing). I also noticed that, when I played with everything maxed out at 1280 x 854, the foliage beneath my vehicle wouldn't re-render as I drove: it was as if my vehicle were killing all the plant life I ran over. At 800 x 600, though, the foliage correctly redraws, once again leading me to believe that at my top resolution I was blowing the texture cache big-time, and that the freezes I saw were at points when a new shader or particle system was instantiated, with the obvious impact from getting the necessary data over the bus to the VRAM. Still a bit surprising on a 128M VRAM system, but you can't win 'em all, and the game is totally playable at 800 x 600. Heck, I even took out a hovercraft with a 120mm HEAT round manually aimed today. Of course, he got me back scant minutes later...

[aittam]

Paul I'm running it on a Pb 1,33/768 ram, the setting that you should absolutly turno off is the particles, otherwise i'm using the same as yours

[poesel]

I'd rather turn the foliage off as the particles give you a hint at if you got a penetrating hit.

[Paul Snively]

I'm having great fun at 800 x 600 with all options except HDR on and maxed out, so I think I'm going to leave it at that. The landscape is a bit TOO stark with foliage off, IMHO, and I concur with poesel71 on the value of the particle systems.