> Michael Kifer writes:
> > > > > > The overhead for HiLog in the loss of some indexing.
> > >
> > > To quote, "In XSB, HiLog using specialisation clearly outperforms the
> set of
> > > generic predicates; HiLog programs run between 7 and 8 times than
> generic Prolog
> > > programs. Furthermore, compared to the specialised generic HiLog
> predicates, the
> > > non-generic Prolog predicates execute only 10-13% faster."
> > >
> > > This 10-13% is more than compensated for with efforts from AMD and Intel
> ;-)
> > >
> > > I wholeheartedly agree with the conclusion from the authors of that
> paper:
> > >
> > > "... HiLog, Prolog programmers would rightfully demand future logic
> programming
> > > systems extended to support HiLog functionality."
> >
> >
> > We did not find that specialization works for us. Perhaps for some
> > programs, but not for our benchmarks.
> > In fact, for the combination of F-logic and HiLog the gain should be
> > minimal. So, Flora, in fact, disables specialization due to some other
> > negative considerations.
>
> The assumption made in the paper, which resulted in the 10%-13%
> number, was that they were essentially Prolog programs, except using
> variable or structured predicate names. Flora has MUCH more going on,
> being a compiler that generates XSB code. The Prolog programs
> generated by Flora are programs no user would ever write by hand
> (which is one of the strengths of Flora, but also one of the
> difficulties in getting an efficient implementation by translating to
> Prolog.)
Right. In F-logic + HiLog the vars are over function symbols (usually in
the 2nd argument), not predicates, so specialization does not help much. On
top of it, we discovered (and reported) a bug, where implementation of the
specialization was causing an error. So, this was the ultimate reason to
disable this feature.
--michael
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