[LAU] eliminating xruns on 64-bit Arch ?

Greetings,

I like my Arch system, but its rt performance is simply not so good as
my old 64 Studio installation. I think I have it optimized, but I wonder
if there isn't more I could do to eradicate the occurrrence of xruns
when recording with Ardour. Technical details follow.

uname -a reports these facts :

     Linux BigBlack 3.0-ARCH #1 SMP PREEMPT x86_64 AMD Athlon(tm) 64
Processor 3200+

The relevant entries in /etc/security/limits.conf

     @audio - rtprio 99
     @audio - nice -10
     @audio - memlock unlimited

I know about nice. IIRC these settings were default values.

The hardware is an M-Audio Delta 66 system, with a separate preamp. Some
relevant JACK (0.121.3) settings :

     /usr/bin/jackd -P89 -t5000 -dalsa -dhw:0 -r48000 -p128 -n2 -Xseq

I usually get two or three xruns per half-hour session, as compared to 0
with 64 Studio. Btw, I'm not comparing the distros, just the performance
stats. I have no interest in returning to older systems, but I have much
interest in improving the ones I'm running now.

This bothers me :

     [dlphilp@email-addr-hidden etc]$ cat /proc/interrupts
                 CPU0
        0: 50 IO-APIC-edge timer
        1: 4 IO-APIC-edge i8042
        7: 1 IO-APIC-edge parport0
        8: 2 IO-APIC-edge rtc0
        9: 0 IO-APIC-fasteoi acpi
       12: 6 IO-APIC-edge i8042
       14: 0 IO-APIC-edge pata_amd
       15: 27164 IO-APIC-edge pata_amd
       16: 788897 IO-APIC-fasteoi ICE1712, nvidia <---- Ouch !!!
       17: 144 IO-APIC-fasteoi firewire_ohci
       20: 49995 IO-APIC-fasteoi ohci_hcd:usb2
       21: 87877 IO-APIC-fasteoi sata_nv
       22: 2124 IO-APIC-fasteoi sata_nv, hda_intel
       23: 82436 IO-APIC-fasteoi ehci_hcd:usb1, eth0

Yep, that's my video card. Can I reassign the IRQ - preferably via
software - for one of those devices ? If so, how and in what order ? I
know about the rtirq script but there seems to little information
regarding its use with a kernel such as mine (Rui ?). Btw, I know that
an updated kernel is available from pacman and will gladly install it if
recommended.

Please advise if other information is required.

Suggestions and recommendations are most welcome. However, before
recommending an rt kernel please note that I need hardware accelerated
3D. Ditching the nVidia binary is not really an option yet, so any
suggested kernel must get along with the nVidia driver.

Best,

dp

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Received on Wed Dec 14 16:15:01 2011