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 files are sblasa_small.in, sblasb_small.in, and sblasc_small.in and the large data files are sblasa_large.in, sblasb_large.in, and sblasc_large.in. 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 sblasa_small.in, M and N are large but K is small, while in sblasb_small.in the small parameter is M, and in sblasc_small.in 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)

Go to LAPACK/TIMING and 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 6.7.1, 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 equation routines. If necessary, the large data set can be simplified by using only one value of LDA.

b)

Run the programs for each data type you are using. For the REAL version, the commands for the small data sets are

• xlintims < sblasa_small.in > sblasa_small.out
• xlintims < sblasb_small.in > sblasb_small.out
• xlintims < sblasc_small.in > sblasc_small.out

or the commands for the large data sets are

• xlintims < sblasa_large.in > sblasa_large.out
• xlintims < sblasb_large.in > sblasb_large.out
• xlintims < sblasc_large.in > sblasc_large.out

Similar commands should be used for the other data types.