We are looking at working with Intel integrated graphics adapters for future versions of our products to provide acceleration in our real-time video and 3D products. In doing this we have run into a very major performance problem with Windows Vista. What we are doing is using DirectX9 to perform computations on the GPU, we then bring that data back into system memory using IDirect3DDevice9::GetRenderTargetData. On an identical dual-boot machine, if you use WindowsXP we typically can recover about 900Mb/s of data in this way, using Windows Vista we see a ~80% speed drop to about 200Mb/s. We have tried different chip-sets, CPUs, drivers, 32/64bit applications and consistantly see this behavior across all of them.
This can easily be reproduced by simply downloading the following application and comparing the results on Vista and XP.
http://www.seriousmagic.com/3D-DloadBenchmark.zip
Although this is a relatively old DX application, we have reproduced the same results with our own code as well (both DirectX9 and DirectX9Ex). I would be more than happy to share this to help debug this problem if it would work.
For us, this is pretty much a show-stopper problem but I would imagine that this is a huge issue for anyone else who has any need for any kind of GPGPU processing on Vista as well.
Thanks a lot for any help or advice,
Andrew Cross, Ph.D
VP of SW Engineering,
NewTek,
www.newtek.com
