Re: [glob2-devel] Optimization suggestions (Map::updateLocalGradient())

[Joe Wells]

Erik Søe Sørensen <address@hidden> writes:

> Hello,
> I have been doing some profiling on Globulation 2, and found some useful
> results.
> (I began doing this because the Ubuntu release (0.8.21) had periods of
> 100% CPU activity, but that seems to have been fixed :-)
>
> Map::updateLocalGradient() seems to be a bottleneck (~40% of the time
> spent there).
> In this function, there are at least two opportunities for speed
> improvement.
>
> For 21% improvement (of the function's run time), get rid of the array
> introduced in Map.cpp:3889:

Thank you very much!!!!

Please continue to do this with new releases!!!

This is great!!!

By the way, can you please write a short profiling “how to” explaining
what exact commands you typed to obtain this information?  That would
be really helpful (because on different machines and/or with different
configuration options different portions of the code might be the
worst spots, so it would be nice if other people could easily do the
same profiling).

-- 
Joe

> (This happens at several other locations, by the way... the second-worst
> place in Map.cpp appears to be in Map::updateRessourcesGradient(), and
> it'might also be worth the attention :-)
>
> And another thing, now we're at reading code:
> A couple of places in Map::updateLocalGradient(), there is code like this:
>         if (xxi<0)
>            xxi=0;
>        else if (xxi>31)
>            xxi=31;
>       if (yyi<0)
>            yyi=0;
>        else if (yyi>31)
>            xxi=31; // <-- Shouldn't this be yyi??
> That last line does look like a typo (or more likely a copy'n'paste error?).
>
> Regards,
> Erik Søe Sørensen
>
> PS: Great looking game, by the way! :-)
>
>
> [Profiling done on a ThinkPad, CPU: Intel(R) Pentium(R) M processor
> 1300MHz stepping 05]
> [Today's lesson: Don't begin profiling on a non-optimized build.]