Timing the BLAS

The linear equation timing program is also used to time the BLAS. Three input files are provided in each data type for timing the Level 2 and 3 BLAS. These input files time the BLAS using the matrix shapes encountered in the LAPACK routines, and we will use the results to analyze the performance of the LAPACK routines. For the REAL version, the small data sets are SBLTIMAD, SBLTIMBD, and SBLTIMCD and the large data sets are SBLTM2AD, SBLTM2BD, and SBLTM2CD. There are three sets of inputs because there are three parameters in the Level 3 BLAS, M, N, and K, and in most applications one of these parameters is small (on the order of the blocksize) while the other two are large (on the order of the matrix size). In SBLTIMAD, M and N are large but K is small, while in SBLTIMBD the small parameter is M, and in SBLTIMCD the small parameter is N. The Level 2 BLAS are timed only in the first data set, where K is also used as the bandwidth for the banded routines.

a)

Make any necessary modifications to the input files. You may need to set the minimum time a subroutine will be timed to a positive value. If you modified the values of N or NB in Section A.8.1, set M, N, and K accordingly. The large parameters among M, N, and K should be the same as the matrix sizes used in timing the linear equation routines, and the small parameter should be the same as the blocksizes used in timing the linear equations routines. If necessary, the large data set can be simplified by using only one value of LDA.

Associate the appropriate input file with Fortran unit number 5.

b)

The output file is written to Fortran unit number 6. Associate a suitably named file with this unit number (e.g., SBLTIMA.OUT, SBLTIMB.OUT, and SBLTIMC.OUT for the three runs of the REAL version).

c)

Run the timing programs in each data type you are using for each of the three input files.