[pulseaudio-discuss] "Hot" function optimization recommendations

Justin Chudgar justin at justinzane.com
Thu Apr 4 16:08:43 PDT 2013

I had experimentally thrown an optimization into my module's only significantly 
warm functions. Since I am a novice, this was a just-for-kicks experiment, but 
I would like to know whether to optimize at all beyond the general "-O2", and 
what platforms are critical to consider since I only use pulse on systems that 
are sufficient to run at "-O0" without noticeable problems beyond unnecessary 
power consumption.

>From another thread:

> I'm not sure what to think about the __attribute__((optimize(3))) usage.
> Have you done some benchmarking that shows that the speedup is
> significant compared to the normal -O2? If yes, I guess we can keep
> them. <tanuk>

I don't know what to think of them either. I did a really simplist benchmark 
with the algorithm on my core i3 laptop initially to determine if it was 
useful to keep everything double or float. There was no benefit to reducing 
presicion on this one system, but that attribute was dramatic. Did not try O2, 
though, just 03 and O0. I thought about messing with vectorization, but I only 
have x86-64 PCs and that seems most valuable for embedded devices which I 
cannot test at the moment.

11: Determine optimization strategy for filter code.

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