ftune.html



Chapter 7
Some Current Architectures; their influence on Fortran programs

alpha:  a Digital Equipment/Intel architecture noted for high clock speed and long pipelines
Operating systems: VMS, NT, Unix, Linux
Usually uses 3 levels of cache, uses double precision (no single) floating point registers, has hardware implementation of SIGN() (f95 style) so that ABS(x) is the same as SIGN(x,1.).

HP-PA (Hewlett-Packard Precision Architecture)
Operating Systems: Unix, NT
Uses single level direct mapped separate instruction and data cache,31 double precision registers accessible as pairs of single precision registers,plus (PA-8000) equally large set of shadow registers, and out-of-order execution. Has fused multiply-add with u-nrounded multiplication (PA8000) Add and multiply of PA8K have 3 cycle latency, and PA8K has 2 parallel divider/sqrt units.
PA8000 favors strongly:
    stride 1 inner loops
Prev Tunning Table of Contents Next