[LAU] rtirq usage

[James Cameron]

On Thu, Sep 03, 2009 at 04:06:29PM +1000, Patrick Shirkey wrote:
> What I am seeing is a massive spike in xruns when running a gui app taht 
> connects to jack (even qjackctl) but nothing when playing a track from 
> the commandline ie mplayer -ao jack. This only happens if the wifi 
> module is installed. Without it there are no xruns for days.
> 
> Unfortunately the snd the video device are on the same irq.
> 
> Does anyone have an idea for why the gui system would become unstable 
> when the wifi device is added?

/me handwaves

It implies a larger than before amount of time being spent inside the
driver for either the wifi device or the video device.  The extra time
or the temporary disabling of interrupts within that driver might be
affecting the delivery and processing of interrupts for the other two
devices.

Consider how the wifi device is communicating with the CPU.  Is it via
PCI or USB?  If USB, then the type of USB controller becomes
interesting.  You may have a controller that meets multiple
specifications, and if so you may get different results by manually
choosing the controller driver.  Controller is often called host.

Look at your modules installed.  Scan for modules with names ending in
hcd.  Test them one at a time.  That is to say, remove all USB devices
except the offending device, remove (rmmod) all of the -hcd modules,
then manually insert one at a time from this set:

ehci-hcd.ko
isp116x-hcd.ko
ohci-hcd.ko
r8a66597-hcd.ko
sl811-hcd.ko
u132-hcd.ko
uhci-hcd.ko

... to find which ones work with the hardware and the device (using
lsusb), then compare your findings against what was originally
installed.

-- 
James Cameron
http://quozl.linux.org.au/