Hi!

I've got a 1.86 GHz Pentium M with 1.5GB Ram and a ATI Mobility FireGL V3200 (128MB, 128bit interface, 12.8 GB/s Memory Bandwidth, 2 vertex-pipes 4 pixel-pipes )

On my Laptop, the game is running smooth arround 85-90 fps. On the XBOX however, it's arround 20-25 fps. Is this normal? If not - what could be the problem? could it have anything to do with one of these two problems:

https://forums.xna.com/thread/11328.aspx
https://forums.xna.com/ShowThread.aspx?PostID=11534

??

Please help me - We have to present the game on next tuesday and it would be quite important to have it running on the XBOX...


Thanks a lot!

I also had serious performance problems on the 360 and found 2 things which really saved me:

• Make sure that any tight loops which pass structs around do so by ref rather than by value.  I had some by-value passing in my collision code which runs frequently and replacing everything by ref gave me some serious performance boosts.
• Run the CLR profiler.  This is probably causing even more of a problem.  The garbage collector on the 360 is not as efficient as on the PC.  Once I reduced nearly all of my runtime heap allocations my application ran incredibly smooth.

Hey Jusy,

50 GCs for 60 seconds is horrendous, I'm not sure how you can be getting even 40 fps.

My advice would be to run the CLR profiler on a Windows version of your game, if at all possible. The way you allocate your objects won't be different between the two platforms (unless you are going out of your way to make it so), so the windows version will still show you the areas where the most objects are allocated, what those are, and where you should focus your efforts. Hopefully you'll find a few places where you can do some one-time allocations and see a significant speed up.

The text was actually ambiguous. Was it 50 GCs a minute or 50 GCs total at that point? It really doesn't hurt anything if your menus and game initiation steps are causing GCs since framerate isn't a big deal at that time, but 50 GCs over the course of a gameplay minute is something to look into.

MrLeebo:

The text was actually ambiguous. Was it 50 GCs a minute or 50 GCs total at that point? It really doesn't hurt anything if your menus and game initiation steps are causing GCs since framerate isn't a big deal at that time, but 50 GCs over the course of a gameplay minute is something to look into.

o KB o:

- The GCs' number goes up by 1 every 10 seconds --> 6 GC's/1 min

- And the "GC Latency Time (ms)" field is increasing by ~11 or 12ms when the collection occurs --> so I think that 1 GC is taking 12ms, right?

Yep. Those numbers look fine, so GC is not your problem.

This talk has some info that might be useful. I would start by making sure you aren't doing any of the Really Bad Things ^(tm), such as reading renderstate values back from the GPU, or using StateBlock or SaveStateMode. Once you eliminate those possibilities, use a Windows profiler (eg. NProf) to find out where your CPU time is being spent in the Windows version of your game, then try to speed up whatever methods it shows as the hotspots.

using StateBlock

Why would using StateBlock be slow, assuming you configure it once and use it many times?

The D3DX stateblock implementation is inefficient even on Windows, but spectacularly inefficient on Xbox.

Shawn Hargreaves:

This talk has some info that might be useful. I would start by making sure you aren't doing any of the Really Bad Things ^(tm), such as reading renderstate values back from the GPU, or using StateBlock or SaveStateMode. Once you eliminate those possibilities, use a Windows profiler (eg. NProf) to find out where your CPU time is being spent in the Windows version of your game, then try to speed up whatever methods it shows as the hotspots.