Performance difference between Vista and XP Using the visual profiler

Hi All,

My raytracer is running about 20% faster in XP than in Vista. I am using CUDA 2.2 and the updated visual profiler. It seems the number of instructions in Vista is higher than in XP, and so is the CPU time for a kernel execution. Although, the GPU time for kernel execution and memcopy is faster…


Timestamp GPU time CPU time Instructions
40194.9 memcopy 1195.87 1678.05
59841.7 memcopy 5161.7 6189.75
236990 memcopy 7892.29 6406.42
244698 render 22055 27333.9 0.125 80325 428852 313704 3724 1.38319e+06
876301 memcopy 7850.75 5036.89
881408 render 22050.6 27699.6 0.125 80325 428852 313704 3724 1.3811e+06


Timestamp GPU time CPU time Instructions
20012.5 memcopy 82.016 418.838
26163 memcopy 341.056 727.327
269437 memcopy 517.664 680.254
270262 render 22130 35705 0.125 80325 428852 313704 3724 1.70321e+06
892601 memcopy 517.312 637.441
893336 render 22128.5 33308.2 0.125 80325 428852 313704 3724 1.7029e+06

Does anyone have a reason for the big difference in CPU times for the two profiles? And the number of instructions?

Also, I have this:

dim3 block(8, 8, 0);
dim3 grid(width / block.x, height / block.y, 1);

CUDA_SAFE_CALL(cudaGLMapBufferObject( (void**)&out_data, pbo_out));

render<<< grid, block>>>(out_data);

But in the profiler it says:

Kernel details : Grid size: 72 x 72, Block size: 8 x 8 x 8. Why?

Yeah, the driver model in vista is a lot different from XP and therefore your CPU times will be higher in Vista.

Is there no way around this? Is there any performance advantage to using Vista? I don’t want to go back to using XP. Tim Murray can you advise?

No, there is no way around it. XP used XPDM, while Vista and Windows 7 use WDDM. WDDM is radically different, and basically ‘forces’ the graphics drivers to do things a certain way to ensure the stability of the operating system. However, some of the extra code also causes some kernel call overhead, which you really can’t do much about, other than to try to figure out a way to call your kernels less frequently. WDDM shouldn’t slow the kernel itself down though.

I have never compare speed of program which runs on XP and Vista before.

To get the good compare result, can you get the averange time for 10 times or more.

I think that only one time is not enough.

what is the difference about 2 computer: CPU, GPU, FSB…


Hello there. In response to the last question. The exact same .exe file was run on the same pc, same configuration (dual-booting the two OS’s). The tests were run 4 times each. I guess I may have to go back to using XP.

Thank for your reply.

It will be useful for me to chose which OS I should use.

By the way.

I am wonderring about XP will be soon not supported by Microsoft.

So how about with Window 7,

I hope someone around here has done any benchmark to compare speed between XP and Window7.


Well, I can’t give you any benchmarks…but Windows 7 uses the same driver model as Vista, so their performance will likely be similar.

Wow, im not even sure how to generate those logs. I do know this.

I have a PNY Geforce 8400 512 PCI.
I have an old Dell Dimension 3000.
2 GBS Ram

My systems crashes/freezes on Vista Ultimate when I play any avi/divx file. and stutters on Hd content.

Everything plays Absolutely Beautiful on XP Pro Service Pack 2 Hd -content, avi/xvid…

I thought i was going crazy, or had a dying power supply.

XP is just better when using Cuda, AVC Core , or Playing HD content thru VLC player.