I have the same P4 vs. Athlon question as many others, but have a specific application whose performance I must optimize. I run lots of scientific analysis code that I write in (god help me) Fortran. Nothing too memory intensive, just lots and lots of simple floating point arithmetic. At present I run these on a P3 500M with execution times running up to 10s of minutes (and many runs required for a final result).
I see that Intel has just brought out a new Fortran compiler that supposedly generates code optimized for the P4. Assuming I recompile all my code with this new compiler would the resulting runtimes be fastest on a 1.5G P4, or would I do better just using my already compiled code on a 1.2G Athlon?
The P4 simply has an inferior FPU compared to the Athlon. I'm not sure if SSE2 optimised code will improve the P4 FP performance enough to beat an Athlon or not.
December 4, 2000 12:11:42 AM
As for as I know the P4 with SSE-2 optimized code is supposed to beat the Athlon's x87 FP unit. I think that the P4 (running SSE-2 code) will beat the Athlon in P3 optimized code. If the preformance difference justifies the cost is another question altogether.
Maybe if u send Tom some of your code and ask real nice he will add this to one of his benchmarks on his next review of the P4.
This looks like a good real world test that could help people decide if the P4 is really worth the cost.
You may take this into consideration before decided.
P4 with SSE2 is 64bit, x87 in Athlon (and P4, P3 too, of course) is 80bit, which is more accurate.
If accuratcy is important for you then......
December 4, 2000 1:32:07 AM
Thats true, SSE2 is only good up to 64-bit precision. Most scientific and 3D modeling programs use 80-bit precision exclusively and won't be incorporating any SSE2 code for those portions. If accuracy is of any importance, the Athlon is the only way to go, but I personally would wait for the palamino to show up.
I'll bet money that the P4 will do it faster- seeing how your saying that Intel has a P4 compiler for Fortran. I've never seen an Athlon optimized compiler for Fortran. I also doubt that SSE2 will really matter, since SSE is really made for multimedia and graphics crap- not compiling. It's really all about the FPU, like u said before. Not only that, i believe the P4 has dual ALU's which would come in handy for you. Someone said earlier it would be an interesting benchmark- i agree.
PS, i'm making a logical decision here, not one based on which is better. I hate intel and love AMD- but i really do think the P4 would be better for this. Also, what the hell are u programing with FORTRAN?! LOL.
December 5, 2000 7:32:06 AM
The easiest and cheapest solution is of course an AMD Athlon. Its FPU is the fastest of all x87 fpu units. But if you plan to port to a new compiler anyway you may whish to investigate the compiler options before bying a new PC.
If it can do SMP, the fastest would probably be dual PIII.