I am new to this forum. I have a dilema here. I purchased a compq R4100 notebook last year. I came with amd64 3200+ socket 939 venice core, 1GB PC2700 ram, 40GB 4200RPM HD. A couple weeks ago i upgrade the cpu to 4000+ for pure number crunching performance. I am using my lappy for solving complex physics problems that usually takes weeks to compute. the reason I am buying this laptop is because its upgradable to 4000+ amd cpu. And from my understanding, 4000+ means I get a cpu perfomance equal/close to p4 4GHz. I bencmarked this lappy with my office PC. Office PC has the following specs: P4 3.06 533FSB socket 478 2GB pc3200 ram, SATA HD. NOw at this point I know that my lappy hd cant keep up with sata pc hd. so I ran a computation that uses little hd. here are the results:
FLUENT software: 50-67% increase in performance favor 4000+
Tecplot software: 25-30% increase in performace favor 4000+
Fortran code (compiled using intel fortran compiler): 10% increase in performace favor P4.
To me this is not acceptable. I know about how intel developer engineers criple their software performance in a non intel product environment. Is there any way I can get the 30% performance gain over P4? I really need speed to complete my work. Note that all 3 benchmarks are done under windows xp os. I tried to compile the program using gcc in the x86_64 fedora core 5 linux os. I used f2c converter to conver fortran 77 code to c code. when I compile, I invoke the following flags: gcc *.c -lf2c -lm -O3 -mture=k8 -march-k8
But still I dont see any performance gain. Does cpu clock frequency really matter for speed? Why the first 2 benchmarks favors the 4000+.
Different processors are good at different things. Take a look at the Tom's CPU charts under Whetstone and Dhrystone. My guess is that the process you are complaining about requires the kind of opps that Intel chips are better at.
Edit: This probably means that recompiling won't help. You can't just change what type of operation is required to perform a calculation. An example: Say you really like adding. Not only do you like adding, you're good at it. You're not good at square roots (then again who can do these w/o a calculator these days anyway). You couldn't change the square root problem into an adding problem to make your life easier. If I'm wrong about this someone tell me how and I'll love you forever... maybe not forever... maybe not even STRONGLY like you... oh well, you get the idea.
There is a speciall instruction that make use of sse2. Both CPUs have the same instruction, except amd has additional 3dnow instruction. I think the intel compiler does something when it runs in amd machine. I used the patch from the site, still no improvement.