[postgis-devel] contains optimization

Robert W. Burgholzer rburghol at vt.edu
Thu Jul 26 09:00:53 PDT 2007


Dave,
Thanks for the information.  Alas, if it had only been so simple as inlining...


Quoting David Fuhry <dfuhry at cs.kent.edu>:

> Robert,
>
>     Your proposed change is called inlining [1].  A compiler is smart
> enough to automatically inline such small functions directly into the
> code of point_in_ring.  Manual inlining can make code harder to read &
> maintain.   As Charlie suggested earlier [2], you should profile the
> code to see if this is really a bottleneck.
>
>     For optimizations, pre-change & post-change performance numbers are
> what's needed to convince people that the change is worthwhile.
>
> Dave Fuhry
>
> [1] http://en.wikipedia.org/wiki/Inline_expansion
> [2]
> http://postgis.refractions.net/pipermail/postgis-devel/2007-July/002692.html
>
> Robert W. Burgholzer wrote:
> > I am running this by the list first, before I try it myself to get
> feedback. I
> > will try it on my machine then post results.  Once again, I am a green C
> coder,
> > and thus, am just making these attempts based on googled optimization
> > suggestions.
> >
> > I have seen that it is advised to NOT make function calls within loops as
> they
> > add to overhead, so I am proposing to move the function:
> >  determineSide(POINT2D *seg1, POINT2D *seg2, POINT2D *point)
> > into the calling function:
> > point_in_ring(POINTARRAY *pts, POINT2D *point)
> >
> > since it is only a one line function anyhow, and should not muddy up the
> code.
> >
> > r.b.
> >
> >
> > --
> > Robert W. Burgholzer
> > --
> > Finding the occasional straw of truth awash in a great ocean of confusion
> and
> > bamboozle requires intelligence, vigilance, dedication and courage.  But if
> we
> > don't practice these tough habits of thought, we cannot hope to solve the
> truly
> > serious problems that face us -- and we risk becoming a nation of suckers,
> up
> > for grabs by the next charlatan who comes along.
> > -- Carl Sagan, "The Fine Art of Baloney Detection," Parade, February 1,
> 1987
> >
> > Online Workout Editor:
> > http://www.swat-swimming.org/workoutlog/
> > http://soulswimmer.dynalias.net/
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--
Robert W. Burgholzer
--
Finding the occasional straw of truth awash in a great ocean of confusion and
bamboozle requires intelligence, vigilance, dedication and courage.  But if we
don't practice these tough habits of thought, we cannot hope to solve the truly
serious problems that face us -- and we risk becoming a nation of suckers, up
for grabs by the next charlatan who comes along.
-- Carl Sagan, "The Fine Art of Baloney Detection," Parade, February 1, 1987

Online Workout Editor:
http://www.swat-swimming.org/workoutlog/
http://soulswimmer.dynalias.net/



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