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By default most Linux distributions have the cpuscaling service on by default. In principle, it should "get out of the way" and run the processor at full speed once there is significant load. However, it seems plausible that that it could get in the way, possibly intermittently.

Has anyone measured any significant impact of this feature, with respect to real-time audio recording/production/processing?

What would be a good approach to try to detect/measure whether this service has any effect on my system's performance?

Dave
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  • This question appears to be off-topic because it is about general computing and is only tangentially related to audio production. You could substitute any other high performance activity for real-time audio production and the answer would be the same. – AJ Henderson Sep 06 '13 at 16:18
  • I do not agree. There has always been an active discussion related to what chipset/CPU/OS/etc.. is better for audio production in terms of performance/stability/etc.. And I think this question is perfectly valid. It is true though, that the answer might be very similar for general performance issues but audio has its own specifics which could be addressed separately. –  Sep 07 '13 at 01:29
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    This isn't actually so much about general high-performance computing, but you could argue it is about general low-latency computing. –  Oct 09 '13 at 12:58
  • definitely the latency. can it be configured to ramp up quickly and let go slowly? – georgi Feb 05 '14 at 09:30

3 Answers3

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Cpuscaling does not have an effect for professional audio production, because the cpufreq is increase so much faster than any sudden performance needs can arise. The only negative impact would be dropouts, and you will hear them and read them in audioserver logfiles. But the do not occure from temporary lower cpufreq but from bad configured system, using the wrong scheduler or jamming the system.

Zimmermann
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The easiest way would probably be to check the speed at which the CPU is running. Just about any performance monitor should be able to tell you this. If the CPU isn't being scaled up when running a CPU intensive program, then it would be having an impact, but generally such system automatically increase CPU speed as soon as the system is using more than a certain % of CPU time, so it's doubtful that it should cause a significant issue.

AJ Henderson
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  • What are useful Linux tools to "check the speed at which the CPU is running"? –  Sep 06 '13 at 18:57
  • @Dave - I'd ask about performance monitor tools on the Linux SE. I honestly don't use Linux, so I don't know personally. I just know the basis behind cpu scaling in general. – AJ Henderson Sep 06 '13 at 19:05
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Scaling the frequency for example down to half means the data rate is halved for the audio. However, audio data has very low bandwidth requirements in modern computers so the real-world effect of this will be minimal.

It would only be under very high load (or if you use a high number of channels) this may have an actual effect. If you use your system mainly for audio production you probably want to turn off this service as you want actual frequencies for your audio monitoring.

I believe the main purpose for this service is a more generic use where you may run Linux on a laptop and batteries, and can therefor contribute to "save" a little bit of energy.

epistemex
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    Once again, the issue with (professional) audio is indeed seldom total bandwidth, but what's absolutely crucial is latency. –  Dec 07 '13 at 13:45