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We have same codes run the two machine(both linux): Pentium III 1.0GHZ and Xeon 1.8GHZ, and we expect to see faster run on Xeon machine since it has faster CPU and more memory.
1 Our code is Fortran code, we use f2c to convert the codes to C codes first, then use GCC to compile them. Codes run well on both machines, but it just runs slower on the faster machine(Xeon 1.8GHZ).
2 Then we use G77 to compile and link, there is no error when we do so, but we get incorrect results on both machines.
3 When we test some very simple codes on both machines compiled by G77 or GCC with f2c, the results show that :
codes run faster on faster machine(Xeon1.8GHZ) if compiled by G77, otherwise they run slower on faster machine(Xeon1.8GHZ) if compiled by GCC with f2c.
Is something wrong with software or CPU structure ??
Might be because clock speed is not everything. Not being too familiar with architectures, it'd be hard to say why it's faster on one of them - it depends a lot on what kind of code it is. Cache size could make a huge (order of magnitude) difference if you're doing a lot of memory references, for example. If you have a program that does lots of memory I/O, a 1Mhz processor with a nice big L1/L2 cache will perform faster than a 2Ghz processor with no cache.
So in a way, you may be comparing apples with oranges (or with Intels )
Maybe using the Intel (I believe it may be non-free, I got a free copy on a magazine a while ago) may make a difference? I'm not sure it will make a difference but it might be worth a try if you're really bothered