[linux-audio-user] kernel - using rtlimits, realtime_lsm

Sylvain Reynal reynal at ensea.fr
Wed Dec 21 20:38:28 EST 2005


On Wednesday 21 December 2005 23:24, Florian Schmidt wrote:

> (X) Complete Preemption (Real-Time)
>
> This also introduces the prioritization of irq handler threads i talked
> about. 

Florian,
Is that to say that (cf. your tutorial, 
http://tapas.affenbande.org/?page_id=6) reprioritizing IRQ handlers with 
things like
chrt -f -p 97 `pidof "IRQ sound_car_irq"`
which prove so simple and efficient with an -rt kernel, are just pointless 
with a preemptible kernel (assuming it was compiled with threaded IRQ 
handlers)?
That'd confirm my recent measurements, but still i can scarcely make out why 
this is so.

And while we're at it, i get --amazingly enough-- far more xruns when 
un-threading my PCI sound card IRQ handler (doing echo 0 > /proc/irq/...) 
than when leaving it threaded... 

In any case, thank you for having written this tutorial. Laid out in a 
perfectly clear way (from my point of view), and a really useful counterpart 
to a kernel building tutorial.

Regards,
Syd



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