Re : [proaudio] : Compile a 2.6.25.4-rt5 kernel (was : 2.6.24.7-rt7 - Big performance improvement)

[Mysth-R <mysthr21@xxxxxxxxx>]

2008/6/6, Reuben Martin <reuben.m@xxxxxxxxx>:
> Back on Thursday 05 June 2008, Mysth-R was like:
>> Hi,
>>
>> Finally I compiled a 2.6.25.4-rt5 without any issues.
>> I have just downloaded the linux-2.6.25.4 kernel and apply the
>> patch-2.6.25.4-rt5 on it.
>> Is there others patches that I could apply to improve the performance of
>> my
>> kernel ?
>> In fact, I can't use a latency (referring to Qjackctl) lower than 16ms
>> (256
>> frames / 3 period / 48000Hz) without cracks in sound.
>> I use jackdmp and freebob on a Intel Core duo 2.
>>
>> Do you have some suggestions ?
>
> Have you checked to see what the priority level is set to for the IRQ-Thread
> assigned to your sound device? If it's not a negative number (something
> like -40 or lower) then all the low latency doesn't amount to much if the
> scheduler doesn't know to give the sound device special priority.
>
> -Reuben

Hi,

Well, I don't know how to check the IRQ-Thread...

I just set the rtirq script for my firewire card :

#####################################################################

#!/bin/sh
#
# Copyright (c) 2004-2007 rncbc aka Rui Nuno Capela.
#
# /etc/conf.d/rtirq
#
# Configuration for IRQ thread tunning,
# for realtime-preempt enabled kernels.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License version 2 or later.
#

# IRQ thread service names
# (space separated list, from higher to lower priority).
RTIRQ_NAME_LIST="rtc ohci1394 i8042"

# Highest priority.
RTIRQ_PRIO_HIGH=99

# Priority decrease step.
RTIRQ_PRIO_DECR=5

# Whether to reset all IRQ threads to SCHED_OTHER.
RTIRQ_RESET_ALL=0

# On kernel configurations that support it,
# which services should be NOT threaded
# (space separated list).
RTIRQ_NON_THREADED="rtc ohci1394"

# Process names which will be forced to the
# highest realtime priority range (99-91)
# (space separated list, from highest to lower priority).
# RTIRQ_HIGH_LIST="softirq-timer"

###############################################################

the /etc/init.d/rtirq start script give me :

rtirq.sh: start [rtc] irq=8 pid=346 prio=95: OK.
rtirq.sh: start [ohci1394] irq=19 pid=392 prio=90: OK.
rtirq.sh: start [i8042] irq=1 pid=455 prio=85: OK.
rtirq.sh: start [i8042] irq=12 pid=454 prio=84: OK.

#################################################################


My limits.conf file is set like :

@mysthr2          -       rtprio          90
@mysthr2          -       nice            -5
@mysthr2          -       memlock         512000



Can you tell me more about setting the priority level of IRQ-thread please ?
Cheers,

Mysth-R


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