On Thu, Feb 26, 2009 at 7:35 PM, Patrick Shirkey
<pshirkey@boosthardware.com> wrote:
> 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 had already checked that; it is not a possibility in my computer.
>> 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.
>
Ok, thanks.
>> 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.
>
>
Actually, I am using a realtime kernel. Anyway, I have to make some
more test with the midi keyboards. With one of them, I can play right,
with 64 or 128 fpp, although there are some xruns.
>> Thanks very much,
>>
>> tizo
>> _______________________________________________
>> Linux-audio-user mailing list
>> Linux-audio-user@lists.linuxaudio.org
>> http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
>>
>
>
> --
> Patrick Shirkey
> Boost Hardware Ltd.
>
Thanks,
tizo
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Received on Fri Feb 27 20:15:04 2009
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