Audio latency with JACK, especially regarding buffer size

Hey everybody,

i use an i7-1165G7 Variant with Manjaro. I am currently trying to use Jamulus, but my concern should apply to everyone trying to use JACK-Audio on Linux and the Framework.

My Problem is, that i can’t use any buffer size lower than 256 without having massive XRuns. I’ve tried with Cadence and QJackCtl. Has anyone else, on Windows or Linux, having any luck with lower buffer sizes?

The ultimate Problem is that my Jamulus latency is too high with around 70-80 ms. Unfortunately my server already has 18-20 ms, so no optimal starting conditions there, but still having ~50 ms internal latency sounds a bit high.

You need lowlatency or RT kernel plus appropriate prioritization in limits.conf. Look up documentation about that on or similar.

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Is that really needed today anymore? Afaik all major realtime or lowlatency optimizations are included in the mainstream kernels today. I also got lower latency and buffer size working on a different computer with “same” Manjaro, so same Kernel, up to date etc.

limits.conf is already modified with memlock, realtimeprio etc. for the @audio group.

I don’t know. Last time I tried some years ago, but not too many, I had to install linux-lowlatency on Ubuntu to get low latency. Needed it for Mixxx.

In case you haven’t read this, maybe useful: JACK Latency tests [Linux-Sound]

They also have an up-to-date guide of how to tune your system (including if you really need RT kernel/scheduling) here: System configuration [Linux-Sound]

Actually it resolved itself. The issue wasn’t the kernel, it was that cadence somehow still used the wrong deivce, despite the settings. But after a bit more fiddeling and proofing with QJackCtl turned to the right device, and now it works flawless and with very acceptable latency. My new Problem is the Windows Driver, which introduces massive latency despite the use of Asio4all…