2008/12/17 Jens M Andreasen &lt;jens.andreasen(a)comhem.se&gt;se>: Mr Rui Nuno Capela figured this out for you/us: http://alsa.opensrc.org/Rtirq Not sure why, but rtirq is hard to be found on the internet, these days. The Gentoo-proaudio people have packaged it here: http://download.tuxfamily.org/proaudio/distfiles/rtirq-20071012.tar.gz Or see the main shell script below; the line you want goes like this: grep irq /proc/asound/cards | tac | sed 's/.* irq \(.*\)/\1/' Kind regards. ### ### ### ### ### ### ### cat /etc/init.d/rtirq.sh #!/bin/bash +x # # Copyright (c) 2004-2007 rncbc aka Rui Nuno Capela. # # /etc/init.d/rtirq # # Startup script 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. # # chkconfig: 35 81 19 # description: Realtime IRQ thread tunning. # ### BEGIN INIT INFO # Provides: rtirq # Required-Start: $syslog $local_fs # Should-Start: $time alsa alsasound hotplug # Required-Stop: $syslog $local_fs # Should-Stop: $time alsa alsasound hotplug # Default-Start: 3 5 # Default-Stop: 0 1 2 6 # Short-Description: Realtime IRQ thread tunning. # Description: Change the realtime scheduling policy # and priority of relevant system driver IRQ handlers. ### END INIT INFO # # Won't work without those binaries. for DIR in /sbin /usr/sbin /bin /usr/bin /usr/local/bin; do [ -z "${RTIRQ_CHRT}" -a -x ${DIR}/chrt ] && RTIRQ_CHRT=${DIR}/chrt done # Check for missing binaries (stale symlinks should not happen) [ -n "${RTIRQ_CHRT}" -a -x ${RTIRQ_CHRT} ] || { echo "`basename $0`: chrt: not installed." [ "$1" = "stop" ] && exit 0 || exit 5 } # Check for existence of needed config file and read it. RTIRQ_CONFIG=/etc/conf.d/rtirq [ -r ${RTIRQ_CONFIG} ] || RTIRQ_CONFIG=/etc/default/rtirq [ -r ${RTIRQ_CONFIG} ] || RTIRQ_CONFIG=/etc/rtirq.conf [ -r ${RTIRQ_CONFIG} ] || { echo "`basename $0`: ${RTIRQ_CONFIG}: not found." [ "${RTIRQ_ACTION}" = "stop" ] && exit 0 || exit 6 } # Read configuration. source ${RTIRQ_CONFIG} # Colon delimited trail list of already assigned IRQ numbers, # preventind lower priority override due to shared IRQs. RTIRQ_TRAIL=":" # # Reset policy of all IRQ threads out there. # function rtirq_reset () { # Reset all softirq-timer/s from highest priority. rtirq_exec_high reset # PIDS=`ps -eo pid,class | egrep '(FF|RR)' | awk '{print $1}'` PIDS=`ps -eo pid,comm | grep IRQ | awk '{print $1}'` for PID in ${PIDS} do ${RTIRQ_CHRT} --pid --other 0 ${PID} done } # # IRQ thread handler policy prioritizer, by IRQ number. # function rtirq_exec_num () { ACTION=$1 NAME1=$2 NAME2=$3 PRI2=$4 IRQ=$5 # Check the services that are to be (un)threaded. if [ -n "`echo :${RTIRQ_NON_THREADED}: | sed 's/ /:/g' | grep :${NAME1}:`" ] then PREPEND="`basename $0`: ${ACTION} [${NAME2}] irq=${IRQ}" for THREADED in /proc/irq/${IRQ}/*/threaded do if [ -f "${THREADED}" ] then case ${ACTION} in *start) echo "${PREPEND}: ${THREADED}: OFF." echo -n 0 > "${THREADED}" ;; stop) echo "${PREPEND}: ${THREADED}: ON." echo -n 1 > "${THREADED}" ;; esac fi done fi # And now do the proper threading prioritization... if [ -z "`echo ${RTIRQ_TRAIL} | grep :${IRQ}:`" ] then PIDS=`ps -eo pid,comm | egrep "IRQ.${IRQ}\$" | awk '{print $1}'` for PID in ${PIDS} do PREPEND="`basename $0`: ${ACTION} [${NAME2}] irq=${IRQ} pid=${PID}" case ${ACTION} in *start) PREPEND="${PREPEND} prio=${PRI2}" if ${RTIRQ_CHRT} --pid --fifo ${PRI2} ${PID} then echo "${PREPEND}: OK." else echo "${PREPEND}: FAILED." fi ;; stop) if ${RTIRQ_CHRT} --pid --other 0 ${PID} then echo "${PREPEND}: OK." else echo "${PREPEND}: FAILED." fi ;; status) echo "${PREPEND}: " && ${RTIRQ_CHRT} --pid --verbose ${PID} ;; *) echo "${PREPEND}: ERROR." ;; esac PRI2=$((${PRI2} - 1)) done RTIRQ_TRAIL=":${IRQ}${RTIRQ_TRAIL}" fi } # # IRQ thread handler policy prioritizer, by service name. # function rtirq_exec_name () { ACTION=$1 NAME1=$2 NAME2=$3 PRI1=$4 IRQS=`grep "${NAME2}" /proc/interrupts | awk -F: '{print $1}'` for IRQ in ${IRQS} do rtirq_exec_num ${ACTION} ${NAME1} ${NAME2} ${PRI1} ${IRQ} PRI1=$((${PRI1} - 1)) done } # # Generic process top prioritizer # function rtirq_exec_high () { ACTION=$1 case ${ACTION} in *start) PRI1=99 ;; *) PRI1=1 ;; esac # Process all configured process names... for NAME in ${RTIRQ_HIGH_LIST} do PREPEND="`basename $0`: ${ACTION} [${NAME}]" PIDS=`ps -eo pid,comm | grep "${NAME}" | awk '{print $1}'` for PID in ${PIDS} do if ${RTIRQ_CHRT} --pid --fifo ${PRI1} ${PID} then echo "${PREPEND} pid=${PID} prio=${PRI1}: OK." else echo "${PREPEND} pid=${PID} prio=${PRI1}: FAILED." fi done [ ${PRI1} -gt ${RTIRQ_PRIO_HIGH} ] && PRI1=$((${PRI1} - 1)) done } # # Main executive. # function rtirq_exec () { ACTION=$1 # Check configured base priority. PRI0=${RTIRQ_PRIO_HIGH:-90} [ $((${PRI0})) -gt 95 ] && PRI0=95 [ $((${PRI0})) -lt 55 ] && PRI0=55 # Check configured priority decrease step. DECR=${RTIRQ_PRIO_DECR:-5} [ $((${DECR})) -gt 10 ] && DECR=10 [ $((${DECR})) -lt 1 ] && DECR=1 # (Re)set all softirq-timer/s to highest priority. rtirq_exec_high ${ACTION} # Process all configured service names... for NAME in ${RTIRQ_NAME_LIST} do case ${NAME} in snd) PRI1=${PRI0} IRQS=`grep irq /proc/asound/cards | tac | sed 's/.* irq \(.*\)/\1/'` for IRQ in ${IRQS} do rtirq_exec_num ${ACTION} ${NAME} ${NAME} ${PRI1} ${IRQ} PRI1=$((${PRI1} - 1)) done ;; usb) rtirq_exec_name ${ACTION} ${NAME} "ohci_hcd" ${PRI0} rtirq_exec_name ${ACTION} ${NAME} "uhci_hcd" ${PRI0} rtirq_exec_name ${ACTION} ${NAME} "ehci_hcd" ${PRI0} ;; *) rtirq_exec_name ${ACTION} ${NAME} ${NAME} ${PRI0} ;; esac [ ${PRI0} -gt ${DECR} ] && PRI0=$((${PRI0} - ${DECR})) done } # # Main procedure line. # case $1 in *start) if [ "${RTIRQ_RESET_ALL}" = "yes" -o "${RTIRQ_RESET_ALL}" = "1" ] then rtirq_reset fi rtirq_exec start ;; stop) if [ "${RTIRQ_RESET_ALL}" = "yes" -o "${RTIRQ_RESET_ALL}" = "1" ] then rtirq_reset #else # rtirq_exec stop fi ;; reset) if [ "${RTIRQ_RESET_ALL}" = "yes" -o "${RTIRQ_RESET_ALL}" = "1" ] then rtirq_reset else rtirq_exec stop fi ;; status) echo #rtirq_exec status ps -eo pid,class,rtprio,ni,pri,pcpu,stat,comm --sort -rtprio \ | egrep '(^[[:blank:]]*PID|IRQ|s(oft)?irq)' \ | awk 'BEGIN { while (getline IRQLine < "/proc/interrupts") { split(IRQLine, IRQSplit, ":[[:blank:]|0-9]+"); if (match(IRQSplit[1], "^[[:blank:]]*[0-9]+$")) { gsub("[^[:blank:]]+PIC[^[:blank:]]*[[:blank:]]+" \ "|\\[[^\\]]+\\][^[:blank:]]*[[:blank:]]+", "", IRQSplit[2]); IRQTable[IRQSplit[1] + 0] = IRQSplit[2]; } } } { if ($9 == "") { print $0"\t"IRQTable[substr($8,5)]; } else { print $0"\t"IRQTable[$9]; } }' echo ;; *) echo echo " Usage: $0 {[re]start|stop|reset|status}" echo exit 1 ;; esac exit 0

2008/12/19 Jens M Andreasen &lt;jens.andreasen(a)comhem.se&gt;se>: Not really; but, by chance (?), this gives acceptable results on my machine: # cat /proc/asound/cards 0 [Intel ]: HDA-Intel - HDA Intel HDA Intel at 0xf5100000 irq 21 1 [M44 ]: ICE1712 - M Audio Delta 44 M Audio Delta 44 at 0xb000, irq 23 # htop (mmh, how do I copy/paste a curses screen ??) => IRQ-23 gets to run with PRI=-86 => IRQ-21 gets to run with PRI=-85 So, the Delta 44 gets privilege over the HDA Intel, which is what I expect, as the latter only gets used for media playback (Firefox, Mplayer and such). Come to think of it, and as IRQ numbers *do* vary on boot, I am not quite sure if this would be the case for every run ? Also, I do not suppose that both soundcards could ever conflict, as I generally do not listen to Flash videos on one card while doing serious audio work on the other ?