🚀 go-pugleaf

In article <867@oddjob.UUCP> sra@oddjob.UUCP (Scott R. Anderson) writes:
>These results verify that the UNIX f77 compiler is not as efficient
>as the VMS fortran compiler, but the "slowness" factor is actually
>14-19%, not 25-30%.


The comparison between compilers is quite machine dependent, 
hence my vague "25-30%". You quote the numbers for the 780/FPA, which
reflect best on the BSD compiler. I think the rest of the numbers
are also interesting. This is Dongarra again; I have added the time
differences in parenthesis.

                                        RATIO     MFLOP     TIME   UNIT 
Double:  
======
VAX 11/785 FPA    VMS v4.1               63       .20     3.50   10.2
                  UNIX 4.2 bsd f77       67       .18     3.75   10.9 (7%)

VAX 11/780 FPA    VMS v4.1               89       .14     4.96   14.4
                  UNIX 4.2 BSD f77      101       .13     5.67   16.5 (14%)

VAX 11/750 FPA    VMS v4.1               99       .12     5.52   16.1
                  UNIX 4.2 bsd f77      128      .096     7.15   20.8 (30%)

VAX 11/750        VMS v4.1              215      .057     12.1   35.1
                  UNIX 4.2 bsd f77      422      .029     23.7   69.0 (96%)

Single:
======
VAX 11/785 FPA    VMS v4.1               31       .40     1.72    5.02
                  UNIX 4.2 bsd f77       40       .31     2.27    6.50 (31%)

VAX 11/780 FPA    VMS v4.1               49       .25     2.74    7.98
                  UNIX 4.2 BSD f77       58       .21     3.25    9.47 (19%)

VAX 11/750 FPA    VMS v4.1               67       .18     3.75    10.9
                  UNIX 4.2 bsd f77       91       .13     5.12    14.9 (37%)

VAX 11/750        VMS v4.1               38      .089     7.71    22.5
                  UNIX 4.1 bsd f77       04      .060     11.4    33.3 (48%)


Can anyone explain to me why the comparison comes out so different
on the 780/FPA and the 750, for instance?
Anyway. Cheers,

conor rafferty == decwrl!glacier!conor == conor@su-glacier.arpa