Comment by cwillu

Comment by cwillu 10 months ago

Not really any harm in trying, but definitely note that the trail marked “trying scheduler changes to see if it improves desktop performance” is strewn with skeletons, the ghosts thereof haunt audio forums sayings things like “[ghostly] oooooohhhh, the sound is so much clearer now that I put vibration dampeners under my usb audio interface”.

The reason I wrote my original comment is precisely because “audio xruns at a higher latency with lower system load” is a very concrete measure of improvement that I can't fool myself about, including effects like “the system runs better when freshly booted for a while” that otherwise bias the judgements of the uninitiated towards “…and therefore the new kernel improved things!”

There isn't much on a desktop that is sensitive to latency spikes on the order of a couple ms, which a stock kernel should already be able to maintain.

snvzz 10 months ago

It can literally sound better (objectively).

Suppose your audio server attempts fancy resampling, but falls back to a crude approximation after the first xrun.

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cwillu 10 months ago

Theoretically possible, but show me a sound server that automatically drops resampling quality instead of just increasing the buffer size.

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- ssl-3 10 months ago
  
  Perhaps that's a theory.
  In reality, my desktop does-everything Linux rig literally does everything. It's my ZFS file server/NAS, and VM host, and web-browsing machine, and gaming box, and it does everything else I do with a computer at home (except for routing, directly controlling 3D printers, and playing movies on the BFT).
  Sometimes, especially when gaming, sound glitches. It's annoying to me when this happens. (It'd be far worse than annoying if I were doing serious audio work, but I am not.)
  An RT kernel may help with that. Not by automagically adjusting buffers (or whatevers) for a glitch after it happens, but by preventing it from ever happening to begin with.
  (And I intend to find out for sure if I ever get far enough into moving into this new place that I can plug my desktop back in, now that it is a mainlined feature instead of a potential rabbit hole.)
  
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- snvzz 10 months ago
  
  That's a different knob that can be used; Increasing buffer size simply is a different compromise to achieve the result of meeting audio deadlines.
  Quality vs latency, pick one.
  Or just use PREEMPT_RT to tighten the timings for the critical audio worker getting the cpu ;)
  
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  cwillu 10 months ago
  
  JERRY: We didn't bet on if you wanted to. We bet on if it would be done. KRAMER: And it could be done. JERRY: Well, of course it could be done! Anything could be done! But it only is done if it's done. Show me the levels! The bet is the levels.
  Again, the point isn't that there is a possible tradeoff to be made, nor that the configuration option isn't available, nor even that some people tweak that setting for this very reason. It was stated that better RT performance will automatically improve audio quality because the audio system may automatically switch resampling methods on xrun, and that is specifically what I'm doubting.
  The bet isn't that it could be done. Anything could be done! Show me that it is being done!
  
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