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

[Jeremy Jongepier]

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
> it with the CONFIG_FORCE_THREADIRQ.
>
>  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.

Best,

Jeremy