Re: [linux-audio-user] IRQ settings and low latency

Hi, I've been working on getting my linux system set up for recording with jack/ardour. I came across the "Low Latency mini howto": http://www.djcj.org/LAU/guide/Low_latency-Mini-HOWTO.php3 At the end, it talks about setting up IRQs such that the sound card is at a high priority relative to other devices in the system. However, all the information in the doc pertains to non-APIC machines. What about an APIC-enabled machine? The output of 'cat /proc/interrupts' shows my sound card (ICE1712) dead last: CPU0 CPU1 0: 6628091 0 IO-APIC-edge timer 1: 6 0 IO-APIC-edge keyboard 2: 0 0 XT-PIC cascade 9: 0 0 XT-PIC acpi 12: 803 0 IO-APIC-edge PS/2 Mouse 15: 5 0 IO-APIC-edge ide1 16: 0 0 IO-APIC-level usb-uhci, usb-uhci 18: 4178 0 IO-APIC-level libata, usb-uhci 19: 320 0 IO-APIC-level usb-uhci 20: 6406 0 IO-APIC-level eth0 21: 0 0 IO-APIC-level ICE1712 NMI: 0 0 LOC: 6628191 6628246 ERR: 0 MIS: 0 output of: lspci -v -s 02:01.0 02:01.0 Multimedia audio controller: IC Ensemble Inc ICE1712 [Envy24] (rev 02) Subsystem: IC Ensemble Inc: Unknown device d634 Flags: bus master, medium devsel, latency 32, IRQ 21 I/O ports at 8000 [size=32] I/O ports at 8400 [size=16] I/O ports at 8800 [size=16] I/O ports at 8c00 [size=64] Capabilities: [80] Power Management version 1 I've tried manually setting IRQs in the BIOS, moving the card around, etc. No amount of tweaking can move it any higher in the list. (It's set to IRQ 10 in the BIOS) I guess my question is: Does the IRQ priority matter when IRQs are abstracted by the APIC? If so, how does one change the priority in this situation? I'm running 2.4.22, with the low latency and kernel preemption patches installed. Thanks, Greg -- Greg Jednaszewski greg(a)attenuated.org