Hi, i'm Diogo Teixeira from Portugal, student of computer science in Lisbon. I owntwoIntelP4 processors, on both desktop and laptop.
I'm developing a Software Renderer in C++, and i'm having weird results on Intel CPU's, i've tested P2, P3 and P4 so far. The strangest results come from the Pentium4.
It is based on Chris Hecker's Perspective Texture Mapping article,the code does nottake advantageof SIMD instructions, simple FPU computations are being made for each triangle. I was able to strip off most of the code and compiled the problem in3 files.
The small source can be found at:
Performance comparison table:
AMD XP 1500+ (1.3GHz)....... 412fps
AMD XP 2600+ (2.0GHz)....... 607fps
IntelP4 1.5GHz.......................... 6 fps
IntelP4 2.5GHz.........................14 fps
As you can see these numbers are extremely weird, i think it might have something to do with some FPU states i'm not aware of. I've checked and changed my timing code and the numbers remained the same. I've read Intel docs that advise developers to use SIMD code, but even without using them i think the performance shouldnt be that low, should it?
So the problem must lie in my code, any help on this would behighly appreciated!
Thanks in advance:
FPU - Weird Performance
Wed, 03/03/2004 - 02:43