tizo wrote: > 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. > Probably not. But check your bios anyway just in case you can reassign the irq there. > 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?. > > The hda should give you reasonable audio quality and performance but you will get better of both worlds with a professional sound card. Make sure it is usb-2.0 capable if you must use a usb sound card. You could also look into a firewire device which tend to have better latency performance. > 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?. > > If you can get the realtime kernel running it will improve latency performance. But you might find that a standard kernel is good enough for your general needs. > Thanks very much, > > tizo > _______________________________________________ > Linux-audio-user mailing list > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user > -- Patrick Shirkey Boost Hardware Ltd. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
