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From: conor@Glacier.ARPA (Conor Rafferty)
Newsgroups: net.lang.f77
Subject: Re: Wanted: Ultra-fast fortran compiler for UNIX
Message-ID: <10068@Glacier.ARPA>
Date: Sat, 27-Jul-85 00:25:13 EDT
Article-I.D.: Glacier.10068
Posted: Sat Jul 27 00:25:13 1985
Date-Received: Sun, 28-Jul-85 09:31:54 EDT
References: <621@astrovax.UUCP> <9871@Glacier.ARPA> <624@astrovax.UUCP> <867@oddjob.UUCP>
Reply-To: conor@Glacier.UUCP (Conor Rafferty)
Organization: Stanford University, IC Laboratory
Lines: 47

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