[postgis-users] Small speed comparison

[Markus Schaber]

Hi,

I re-ran my benchmarks with a 1.0.0 CVS checkout from today morning, to
see the impact of the alignment issues. I simply added the new timings
after the quoting of the old ones. The hardware setup is the same, and
the table was not changed, so the test environment should be comparable.

Please note that all Geometries are polygonal, so this does not say
anything about other geometries.

> lwgeom=# select geom from adminbndy1;
> Zeit: 8629,822 ms
> Zeit: 6401,693 ms

Zeit: 10556,032 ms
Zeit: 6301,014 ms
Zeit: 5809,858 ms

> lwgeom=# select asBinary(geom) from adminbndy1;
> Zeit: 11648,607 ms
> Zeit: 7845,229 ms

Zeit: 7604,296 ms
Zeit: 7465,358 ms
Zeit: 8062,700 ms

> lwgeom=# select asEWKB(geom) from adminbndy1;
> Zeit: 7824,009 ms
> Zeit: 7308,423 ms

Zeit: 7191,243 ms
Zeit: 7342,762 ms
Zeit: 7214,146 ms

> lwgeom=# select asText(geom) from adminbndy1;
> Zeit: 33655,132 ms
> Zeit: 33154,569 ms

Zeit: 32816,896 ms
Zeit: 32792,680 ms
Zeit: 32645,417 ms

> lwgeom=# select asEWKT(geom) from adminbndy1;
> Zeit: 34402,441 ms

Zeit: 37156,399 ms
Zeit: 35210,384 ms
Zeit: 33757,256 ms

> lwgeom=# select asEWKB(geom)::bytea from adminbndy1;
> Zeit: 7444,995 ms

Zeit: 8681,531 ms
Zeit: 7225,146 ms
Zeit: 7230,526 ms

I woult not try to read too much out of those results (as the test
environment was not 100% clean), but it seems go be a slight speedup. I
could think of three possible reasons:

- Possibly, some optimizations at other places between my first test CVS
  checkout (start of january) and now overrule the effect of your
  alignment work.

- The new code somehow allows better use of processor caches and/or
  pipelines

- My processor (Mobile Intel Pentium 4 @ 2Ghz) profits from the better
  alignment speed-wise.

Personally, I would think that the third variant is the most likely one.

Can anyone do some similar tests on another hardware?

Markus


--
markus schaber | dipl. informatiker
logi-track ag | rennweg 14-16 | ch 8001 zürich
phone +41-43-888 62 52 | fax +41-43-888 62 53
mailto:schabios at logi-track.com | www.logi-track.com
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