Real time kernel exploitation
Alessio Igor Bogani
abogani at ubuntu.com
Mon Aug 11 16:09:23 BST 2008
Hi,
I suggest a simple hack that result in a better system response on
audio related tasks. This hack is based on one of the most important
real time kernel feature: IRQ threaded. For this reason it works only
on this type of kernel.
Prioritizing IRQs reduce possibility of X-Runs happens. As far i know
it the most frustrating event for an UbuntuStudio users.
Let's start with a proof of concept!
A script like this called during boot do the dirty work:
*** /etc/init.d/setirqprio ***
#!/bin/sh
# PRIOVALUE is stored into /etc/default/setirqprio
. /etc/deafult/setirqprio
for irqpath in $(ls /sys/class/sound/card[0-9]/device/irq)
do
irq=$(cat $irqpath)
pid=$(pidof IRQ-$irq)
chrt -p $PRIOVALUE $pid
done
*****************************
As you can see this script increase (to 75) the priority of IRQs of
the all sound cards present in the pc.
Obviously we should place setirqprio into /etc/event.d/ directory, add
capability to turn it on/off and put /etc/default/setirqprio under ucf
to do a great work.
Ciao,
Alessio
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