[LAU] rtirq - what does it improve, and how can I measure it?

Jeremy Jongepier jeremy at autostatic.com
Mon May 7 12:24:52 UTC 2012

On 05/07/12 14:06, Kaj Ailomaa wrote:
> I understand that the rtirq script is designed to raise rtprio for audio
> devices, which is made possible on the vanilla kernel since 2.6.39(?),
> if passing the threadirqs option to the kernel at boot, and having built
>  From my experience, I have not had any performance boost using the
> rtirq script, but I have read about it helping those who are getting
> xruns due to irq sharing.

Hello Kaj,

rtirq allows you to elevate the prios of softirq's which could enhance 
the performance of those prioritized softirq's. So it doesn't really 
boost the overall performance of a system.

> So, I'm wondering. What picture do others have of the benefit of the
> rtirq script?

Without rtirq I simply can't use my FireWire card on my notebook for 
example. The FireWire controller shares its IRQ with a plethora of other 
devices (GPU, WiFi, cardreader) and if I don't use rtirq jackd simply 
won't start.

> ..and are there other ways to measure improvement for audio operation
> other than spotting xruns at different latency settings, and reading the
> rtprio for various devices using the 'ps' command?

Yes, htop and latencytop for example.



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