My Intel Fortran application which uses MKL functions Pardiso and Feast to solve large matrices (of the order of 30,000 rows) only lights up 4 of the 8 threads on an Intel i7-870 processor, whereas an MS-C# application doing non-matrix things lights up all 8 threads. The processor is quite old (2009) and has 4 cores with 8 threads.
Does anyone know why the ifort is only using 4 threads and whether or not I could change a setting when compiling to get it to use all 8 threads? I realise that if all 4 cores are fully busy with 4 threads then the other 4 threads won't help, but I'm just wondering if anyone could shed some more light on the issue.
Peter