[Jack-Devel] CPU load with top is inconsistent

Dear all,
I've been trying to track down how the CPU usage is affected by Jack 
under different conditions of sample rate and period size. Of course I 
am aware low-level stuff such as how ALSA handles the hardware and how 
it transfers the data is relevant, and it may also show higher 
performance with some specific combinations of sample rate and sample size.

Nonetheless, I'd like to have a qualitative comparison between different 
conditions. What I do is run "top" and average the values I find for 
jackd. Unfortunately - and this is startling - when combining jack with 
other clients, such as jacktrip, the measure changes a lot. An example:
-r44100 -p64 with jack only: jack takes 74% CPU
-r44100 -p64 with jack+jacktrip: jack takes 30%, jacktrip takes 33%

I really can't understand why.

By now I'm quite aware that audio software is not subject to regular 
physical laws, is not susceptible of common software engineer best 
practices and does not bend down to any debugger or debug tool but 
printf and the likes. It's a tricky world. But some insight on this 
would be nice. BTW I remember even with Puredata (under both Linux and 
Windows) was impossible to get a correct CPU measure: any tool would say 
different numbers... But maybe it's me! ;)

Regards

-- 

Dr. Leonardo Gabrielli, PhD student
A3Lab - Dept. Information Engineering
Università Politecnica delle Marche
via Brecce Bianche 12, 60131, Ancona, Italy
Skype: leonardo.gabrielli
Web: a3lab.dii.univpm.it/people/leonardo-gabrielli 
<http://a3lab.dii.univpm.it/people/leonardo-gabrielli>

1400576018.13105_0.ltw:2,a <537B1803.7060901 at univpm dot it>