I am performing a sparse matrix vector multiplication using mkl_dcsrmv on a system with ~80,000 degrees of freedom. My matrix is symmetric, so as a first attempt I used the option "SLNCxx" for matdescra and passed in the lower triangular part only. This works fine and gives the correct answer, but on a E5-4650 machine with 32 cores the code maxes out at 8 threads. If I instead call mkl_dcsrmv with "GxxCxx" and pass in the full sparse matrix, the code scales up to 32 threads and completes in roughly half the time as the symmetric version. This code is running with MKL 11.1 packaged with Composer XE 2013 SP1 on Linux. Should I expect the symmetric version of mkl_dcsrmv to execute with fewer threads than the general version? Thank you for your advice.
↧