[maemo-developers] Performance of floating point instructions

[From: Siarhei Siamashka]

On Wednesday 10 March 2010, Alberto Mardegan wrote:
> Alberto Mardegan wrote:
> > Does one have any figure about how the performance of the FPU is,
> > compared to integer operations?
>
> I added some profiling to the code, and I measured the time spent by a
> function which is operating on an array of points (whose coordinates are
> integers) and trasforming each of them into a geographic coordinates
> (latitude and longitude, floating point) and calculating the distance
> from the previous point.
>
> http://vcs.maemo.org/git?p=maemo-mapper;a=shortlog;h=refs/heads/gps_control
> map_path_calculate_distances() is in path.c,
> calculate_distance() is in utils.c,
> unit2latlon() is a pointer to unit2latlon_google() in tile_source.c
>
>
> The output (application compiled with -O0):

Using an optimized build (-O2 or -O3) may sometimes change the overall picture
quite dramatically. It makes almost no sense benchmarking -O0 code, because in
this case all the local variables are kept in memory and are read/written
before/after each operation. It's substantially different from normal code.

-- 
Best regards,
Siarhei Siamashka