[PlanetCCRMA] low latency audio on crusoe laptop

jfm3 jfm3@ouroboros-complex.org
Wed Feb 26 20:59:01 2003

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Using the attached scripted setpci commands I have gotten the audio
latency of my crusoe laptop down to 3 ms. Throughput to anything but the
audio device is worse, but who cares when you're just running one audio
synthesis/analysis process? I might crank up the pci latency of the ide
controller if I ever need to stream audio to or from disk. Results of
latencytest are posted at http://www.ouroboros-complex.org/latency.

My present kernel and alsa packages can be found at
http://www.ouroboros-complex.org/moon. These are compatible with the
Planet CCRMA project. See http://www.ouroboros-complex.org/moon/README.

I have effectively reduced the weight of my rig from 120 to 2 pounds.
Jack still doesn't work, but I can do pretty much everything in one Pd
process anyway. It's no huge MOTM system, but then again, it's not a
huge MOTM either.

Thank you everyone.

(jfm3  2838 BCBA 93BA 3058 ED95  A42C 37DB 66D1 B43C 9FD0)

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#"open up" the PCI bus by allowing fairly long bursts for all devices, incr=
easing performance
#setpci -v -d *:* latency_timer=3Db0

#maximize latency timers for audio, allowing it to transmit more data per b=
urst, preventing buffer over/underrun conditions
setpci -v -s 00:06.0 latency_timer=3Dff =20

# north bridge
setpci -v -s 00:00.0 latency_timer=3D40

# firewire
setpci -v -s 00:09.0 latency_timer=3D10

# ethernet
setpci -v -s 00:0b.0 latency_timer=3D10

# usb
setpci -v -s 00:0f.0 latency_timer=3D10

# ide
setpci -v -s 00:10.0 latency_timer=3D10

# cardbus bridge
setpci -v -s 00:12.0 latency_timer=3D40

# usb
setpci -v -s 00:14.0 latency_timer=3D10