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Everything posted by moon2012

  1. How did you measure this? It makes no sense for Present to block, two lines of code after it's execution... [/quote] dwStartTime of the second time - dwEndTime of the first time = 25ms.
  2. After the function return, we can see the result on screen or it's not guaranteed. I found a strange issue when testing multi-monitor performance(try to get the maximal FPS). For each monitor I create a thread, in the thread function I create a child window, Direct3D device and present continuously. The pseudo code looks like: while(true) { DWORD dwStartTime = timeGetTime(); BeginScene(); ...... EndScene(); Present(); DWORD dwEndTime = timeGetTime(); } dwEndTime - dwStartTime is about 7ms, it seems that the FPS should be 1000 / 7 = 142. but the actual FPS is about 30. I debug and find that the interval after execute the last line code(DWORD dwEndTime = timeGetTime();) and go back to the first line(DWORD dwStartTime = timeGetTime();) is about 25ms, so it slow down the FPS. It seems that the CPU can't get the time slice and can't run this thread's code, but at that time the CPU usage is only about 10%. The test result is base on the machine utilize 4 display cards and 16 outputs, all threads almost get the same result; when only utilize 2 display cards, the actual FPS can reach to 80 for each moniotor. I can't understand why this happen? In despite of Present function is sync or async, after execute the last line code, is should execute the first line code very quickly if cpu usage is low.
  3. Thanks. But It don't understand why in the while loop, the code can't return to the begin quickly unless after the last line code is executed, the thread is suspended by something.
  4. I don't use VSYNC. Since "Present will start to block after the CPU gets a few frames ahead of the GPU", why it's asynchronous? If it's asynchronous, it should return as immediately.
  5. Hi, Is there anybody who has the experience to share textures(in video memory) among multiple GPUs? I'm doing multi-monitor development. On the machine(OS is win7), there are two or more ATI display cards(FirePro 2460 or other), each display card has one GPU and more than one output(FirePro 2460 has 4 outputs). As the SDK mentioned, Direct3D resources can now be shared between devices or processes from Direct3D 9 for Windows Vista, so for each monitor, I create a Direct3D9 device; only one device create the texture and shared it to other devices. This can work well for one display card(that means the machine only use one display card's 4 outputs and connect to 4 monitors), but for two or more display cards, when calling CreateTexture and pass the shared handle to it, it return 0x80070057( An invalid parameter was passed to the returning function). Can anybody tell me that whether Direct3D support it or not? Or other methods? It seems that OpenGL can share textures among multiple GPUs.
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