[LAU] midi keyboards, jackd, low latency

Hi there, Sorry about my previous mail. I was just starting to write a draft about the topics I want to ask, and I accidentally push the send button. Well, my goal is to play two midi keyboards, sending the events through jackd, to qsynth. My computer is a Laptop HP 550, with HDA Intel sound card, 3 GB of memory, and a Core 2 DUO CPU of 1.40 GHz. My OS is UbuntuStudio 8.04, with kernel 2.6.24-23-rt. First of all, I cannot run jackd without xruns, if I configure it with 32 frames per period, or less. I am running it as root, with realtime, and a priority of 70. As soon as I run it, it starts to count xruns, and I am only executing jackd. Looking at the different IRQ, I have saw that my sound card is sharing the IRQ 16 with an USB port, and the video driver. This is a cat of /proc/interrupts: CPU0 CPU1 0: 1026591 1099066 IO-APIC-edge timer 1: 2060 839 IO-APIC-edge i8042 8: 0 1 IO-APIC-edge rtc 9: 121 95 IO-APIC-fasteoi acpi 12: 118454 56308 IO-APIC-edge i8042 14: 6410 5638 IO-APIC-edge libata 15: 5167 6228 IO-APIC-edge libata 16: 624 482 IO-APIC-fasteoi uhci_hcd:usb1, HDA Intel, i915@pci:0000:00:02.0 17: 24009 14458 IO-APIC-fasteoi eth1 18: 0 0 IO-APIC-fasteoi ehci_hcd:usb2, uhci_hcd:usb5 20: 0 0 IO-APIC-fasteoi uhci_hcd:usb3, ehci_hcd:usb6 21: 0 0 IO-APIC-fasteoi uhci_hcd:usb4 508: 378 139 PCI-MSI-edge eth0 NMI: 0 0 Non-maskable interrupts LOC: 295845 239602 Local timer interrupts RES: 34174 96493 Rescheduling interrupts CAL: 10832 457 function call interrupts TLB: 873 742 TLB shootdowns TRM: 0 0 Thermal event interrupts THR: 0 0 Threshold APIC interrupts SPU: 0 0 Spurious interrupts ERR: 0 I have searched a lot on Internet, and even in the list, and I have not found a way to change the IRQ assignments. In fact, I have read some mails that said that I can't do that in a laptop (except in some Thinkpads, where IRQ can be changed in the BIOS), as in PCs this can be done changing the card to other slot. In other places, some kernel parameters were suggested to obtain other IRQ assignments, but the only parameter that change those in my computer, was "acpi=off", and it was not better. In this case, /proc/interrupts shows the following: CPU0 0: 602 XT-PIC-XT timer 1: 209 XT-PIC-XT i8042 2: 0 XT-PIC-XT cascade 8: 0 XT-PIC-XT rtc 10: 2912 XT-PIC-XT uhci_hcd:usb1, uhci_hcd:usb3, uhci_hcd:usb4, ehci_hcd:usb6, eth1, HDA Intel, i915@pci:0000:00:02.0 11: 0 XT-PIC-XT ehci_hcd:usb2, uhci_hcd:usb5 12: 5196 XT-PIC-XT i8042 14: 9987 XT-PIC-XT libata 15: 704 XT-PIC-XT libata 508: 31 PCI-MSI-edge eth0 NMI: 0 Non-maskable interrupts LOC: 87955 Local timer interrupts RES: 0 Rescheduling interrupts CAL: 0 function call interrupts TLB: 0 TLB shootdowns TRM: 0 Thermal event interrupts THR: 0 Threshold APIC interrupts SPU: 0 Spurious interrupts ERR: 0 So, my first question is: is there a way to change my IRQ assignment?, or that really cannot be done in my laptop? I would like to have it in a not shared one, not necessarily in IRQ 9, as with rt kernel a priority raise of an IRQ can be done with chrt. I have also read, that the HDA sound card is not good for audio processing. I am just starting to configure my whole "synthetizer box", so by this time, I am only making some tests with it. But, for the near future, which usb sound card would you recommend?. I also wonder that, if the IRQ of USB ports cannot be change too, I would have some of them sharing some IRQ. Would that affect the performance, having an usb sound card?. And what about the performance of the midi events for the keyboards connected to the laptop?. Thanks very much, tizo