CPU usage: single processor, dual-core

[iatel]

Hi, I have searched the forums but have not found the exact match of problems that I'm having. I use Intel Visual Compiler from within MS Visual Studio on a dual-core Xeon 3.73GHz processor. The program that I have uses a bunch of fortran-90 code which, yes, once upon a time I used the Compaq compiler with - but I recompiled it on the new compiler for EM64T, as I have a 64-bit OS. When running the code, I am seeing ONLY 25% CPU usage (one-half of one core??). The whole reason I have this mega-machine is to increase the running speed of my code to lightning - and so far, I think, I have a slowdown. I have seen you give advice for parallelization with dual-core processors, but this is not an MPI situation. Thanks! (Feel free to give instructions for dummies).

[Steven_L_Intel1]

Have you actually timed it?

What you are seeing is all of one core being used. Your processor supports Hyper-Threading and Windows thinks that means it has twice the processors it actually has. This will cause the Task Manager display to show the program taking half as much CPU as it really is.

What you need to do is thread your application, not use MPI, to take advantage of the second core. You can try the compiler's auto-parallel option or add OpenMP to the application. There's extensive discussion of this in the compiler documentation sub-book "Optimizing Applications".