[Openal-devel] OpenALsoft CPU usage?

[Chris Robinson]

On Tuesday 26 May 2009 7:57:14 am Christian Ohm wrote:
> I did the tests mentioned before. I repeated them after updating to ALSA
> 1.0.20, the results are below (just copied the test notes, I hope it is
> clear enough). I'll also attach my OpenAL config, though I think it's just
> the defaults.
>
> I also bisected to find what caused the difference between 1.5 and 1.6. The
> smaller differences are not that easy to find, since the results vary some
> percentage points depending on the in-game action. I can try to isolate
> those as well, but that needs some more time (need to do several test runs
> per version to get a good average, and a good cut-off point).
>
> If you need some more info, or want me to do other tests (of a more
> predictable nature perhaps), feel free to ask.

Hi, thanks for the info. :)

Those results are pretty odd. All that patch does is add 8 floating-point 
additions per sample, which is comparatively minor compared to what it already 
did.

Maybe because the sends are being updated through a pointer to an array in the 
source struct, it's not optimizing it as well as when it was on the stack.. 
I'll have to see if putting them back on the stack helps at all.

Also FYI, I made a bit of a change in the GIT version to the ALSA backend 
which may help the mixer's efficiency a bit. Not sure how much of an effect 
it'll have if the sample mixing loop is being a killer, though.