   Network causes jerky rendering
  I have been struggling with a strange problem that makes Direct3D rendering jerky. I noticed a periodic jumps in the smooth moving geometry in my app and I started debugging my timers and closed all other running programs but to no avail. Then, in a moment of panic, I unplugged the network cable and the jerkyness disappeared! Ok, I'm being flooded on university network but after doing some packet sniffing this possibility was ruled out too. Infact I even connected my computer to a router that wasn't connected to anything else and the problem was still there. I then killed all possible windows services (even DNS and DHCP) in the hope that some service was doing something nasty when a network connection was detected, but still jerky.The jerks come with a frequency of roughly 1 second and the DX samples are also affected. It's mostly visible on the moving airplane in the ShadowMap sample. Funny thing is that OpenGL rendering does not seem to be affected!Has anybody ever experienced anything like this before or has an idea how to fix this problem?System specs:Windows XP Professionel - SP2Intel P4 2.8Nvidia GF6800 - Forceware 84.21Intel PRO/1000 CT integrated network adaptor   
  When running one of the DX SDK samples in windowed mode, try clicking on the window title and holding down the mouse button.  I have noticed a little strange behaviour that apps sometimes do exactly what you describe - jerking every second or so.  From what I have seen (and from what I remember) it mostly happens in windowed mode.  Are you still getting the same jerkiness when running in fullscreen?   ;  I've had the exact same problem for a long time. I haven't noticed significant jerkiness in other apps than mine before, but I checked out the Shadowmap sample that you mentioned and the jerkyness was there too. And when I unplugged the network cable the jerkyness disappeared.I've also found a completely different way to "fix" the problem: run the app in fullscreen mode using the debug directx-runtimes. Works both in my program and the Shadowmap sample.The specs:Windows XP Home SP2P4 2.8 GHzGeforce 5900UAsus P4P800 Deluxe with 3Com Gigabit LOM integrated network adapterNetgear RP114 router   ;  What does your profiler tell you?  It's the only way to accurately diagnose this type of problem.If you don't have a profiler you should get one and learn how to use it.  There are free profilers out there, such as CodeAnalyst.  There are .net profilers like nprof, and .net 2.0 has a Microsoft profiler.For games programmers, some of the most important tools are a good compiler, a comprehensive debugger, and a great profiler.   ;  This sounds similar to a problem I have had in the past, I've discovered that Direct-X can be significantly interrupted by system activity.  I had an app that could be run at over 1000 FPS and because of other system activity, ie something like desktop windows being moved around, it could be dragged down to below 50 FPS. I never really solved the problem, all I did was to pre-render a stack of frames in one thread (only when the stack fell below a certain level), then in another thread pull from that stack every time I wanted to present. If some system activity occurred to slow the render thread down, there was ( to a certain degree) no stuttering because of the pre-rendered frames.I'm not saying this is an ideal solution for you, but I think that people have to be aware that Direct-X is not a guaranteed FPS delivery system.;  Fullscreen mode did indeed solv the problem - Thanks! I'm still puzzled as to why the network connection has any influence on windowed mode rendering.frob,Admittedly my profiler does not tell me anything because I have not really gotten into using one yet. I know that a profiler is an awesome tool so it's one my todo list.However in this particluar case with network connection and windowed mode what would you imagine a profiler could reveal? I mean it might be a problem if the jerkyness is due to some kernel mode proces.   ;Quote:Original post by DonnieDarkoHowever in this particluar case with network connection and windowed mode what would you imagine a profiler could reveal? I mean it might be a problem if the jerkyness is due to some kernel mode proces.It will reveal what function(s) the system is in when the slowdown occurs.  Since you said it is happening on a regular basis, the offending function(s) will have a very high running time.If it is happening outside of your program, some profiling tools will state how long the kernel interrupted you for, other profiling tools will say that it wasn' inside your program by not including the time in the profile results.And just in case this might be the problem: Never look at DX performance when using the Debug drivers.  It's also a generally good idea to generate optimized debug builds or optimized release builds with external debugging files when you profile.   