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Re: PL/I nostalgia

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From: "glen herrmannsfeldt" <gah@ugcs.caltech.edu>
Sent: Wednesday, 19 September 2012 1:56 PM


> robin <robin51@dodo.com.au> wrote:
>>> [The code fron PL/I F was comparablw to Fortran G, but much worse than
>>> Fortran H.  The PL/I optimizing compiler's code was better, but still
>>> not as good as Fortran H and its descendants. -John]
>
> Well, the dynamically allocated variables and save areas for PL/I are
> naturally slower than static allocated Fortran IV.

But not where it counts.  By the time some procedure (such as INVERT)
is called, the array(s) has(have) been allocated.  Allocation is a
once-off task, probably not measurable in terms of time.  And the
FORTRAN IV code was, essentially, rigid, and required re-compilation
for larger arrays.

> Also, many PL/I features naturally don't optimize as well as Fortran.

That may be so, but to have to re-compile the FORTRAN code to deal
with larger-sized arrays counted strongly against it.  As well, PL/I
offered full roll-out of fixed-size array operations Not all arrays
needed to be dynamic.  As well as that, PL/I offered such things as
double precision complex, string-handling, and error recovery.

Error recovery more than compensated for any difference in speed that
may have existed between FORTRAN and PL/I.  Having to re-run FORTRAN
code because of some error to find out what went wrong outweighed any
speed advantage that FORTRAN might have had, because in PL/I, the
error information was already there (including values of variables),
and without necessarily a program termination.  Hence, a re-run of the
PL/I code was avoided.  That was important, not only in terms of
machine time, but also in terms of turn-around time, because
turn-around time in those days was as much as a week.

> Finally I have to hand Tucker's "Programming Languages".
>
> I have one of those. Not my favorite, but not bad.
> "History of Programming Languages" is better.
>
>> Case study 2, matrix inversion with 20 x 20 data:
>
> What page is that on?

Look in the index.

>> with IBM 370-145 FORTRAN (G) execution time 8.41 secs
>>                          (H) execution time 5.28 secs.
>
>> With IBM 370-145 PL/I (F)       execution time 6.31 secs
>>                  PL/I Optimiser execution time 5.77 secs.
>
>> (refer to pages 112 and 279 for times)
>
> Not in the second edition.

>> However, in the case of the PL/I program, Tucker //omitted// to supply
>> the option (REORDER) which is necessary to obtain full optimisation.
>> Thus, the PL/I optimiser execution obtained was larger than it should
>> have been.
>
> When did that appear? I don't remember it in (F).

It wasn't in F, but it was in the optimising compiler, where it counted.

>> It is clear that the times for FORTRAN (G) and PL/I(F) are equivalent,
>> and that FORTRAN(H) and PL/I optimiser times are equivalent.
>
> I suppose. A better test would use a larger matrix, though.

20 W 20 is more than large enough.
It's the size of a typical matrix in a typical job.

>> As well as that, FORTRAN (H) required c. 150K of memory (i.e. a 256K
>> machine) which was far more than the 128K that we had initially,
>> whereas PL/I (F) required only 64K and IIRC FORTRAN (G) a little more.
>
> If you really want to be fair, add the compilation time to the
> run time, then see which one is faster.

Compilation time is only relevant when the run-time is very short.
When speed mattered, it was in long-running executable codes,
in which case, compilation time was unimportant.

To get the entire time for a job, you'd have to add in the link time,
which Tucker didn't provide.

And if compilation time was important, such as in short jobs,
you'd have used PL/C or WATFOR.

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Decades of compiler technology and what do we get? Robert AH Prins <robert@prino.org> - 2012-04-22 18:57 +0000
  Re: Decades of compiler technology and what do we get? Robert AH Prins <robert@prino.org> - 2012-04-22 22:14 +0000
  Re: PL/I nostalgia, was Decades of compiler technology and what do we get? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-23 00:03 +0000
    Re: PL/I nostalgia "robin" <robin51@dodo.com.au> - 2012-04-25 09:07 +1000
      Re: PL/I nostalgia glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-24 23:52 +0000
        Re: PL/I nostalgia "robin" <robin51@dodo.com.au> - 2012-04-28 21:30 +1000
          Re: PL/I nostalgia glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-28 16:11 +0000
            Re: PL/I nostalgia Robert A Duff <bobduff@shell01.TheWorld.com> - 2012-04-29 10:16 -0400
            Re: PL/I code "robin" <robin51@dodo.com.au> - 2012-05-05 00:45 +1000
              Re: PL/I code glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-05-05 05:20 +0000
                Re: Fortran calls, was PL/I code glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-05-06 05:13 +0000
                Re: Archaic hardware (was Fortran calls) "robin" <robin51@dodo.com.au> - 2012-05-09 10:46 +1000
          Re: PL/I nostalgia "robin" <robin51@dodo.com.au> - 2012-09-19 11:04 +1000
            Re: PL/I nostalgia glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-09-19 03:56 +0000
              Re: PL/I nostalgia "robin" <robin51@dodo.com.au> - 2012-09-21 13:53 +1000
                Re: PL/I nostalgia glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-09-21 07:00 +0000
                Re: PL/I nostalgia "robin" <robin51@dodo.com.au> - 2012-09-30 10:45 +1000

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