[linux-audio-user] Ardour, Jack, and 2.6 kernels + XRuns with the Audiophile 24/96 M-Audio

Joel White cv223 at comcast.net
Mon May 31 23:00:47 EDT 2004

Aha, a thread convergence!

I started the "Ardour..." thread lamenting long xruns under the 2.6 
kernels.  Based on recommendations on the list, I went back to a 2.4 
kernel, still having the occasional long xrun.  In the "XRuns..." 
thread, the following from a post by Jan Depner caught my eye:

"What kind of disk drives? Adaptec SCSI controllers can give you 
problems with xruns."

Uh-oh.  I'm using an Adaptec controller on my main board (a 7890).  With 
a little digging, I came up with the following from the ST Audio website 

"The famous Adaptec 2940 SCSI controller series is causing performance 
problems when installed in the same system as our DSP24 series and when 
the audiodata is stored on a SCSI-HDD connected to the controller. To 
get good results in benchmark tests, the Adaptec controller keeps steady 
access to the PCI bus. The result is a reduction of data transfer of 
other PCI cards like the DSP24 hardware. This means that the ASIO/MME 
buffer size (which is the latency) needs to be set to a relative high 
value to avoid stuttered audio playback and drop-outs during recording. 
The performance problems can be reduced if both the DSP24 and the 
Adaptec controller both have a unique and unshared IRQ. Still the 
performance will not be as good compared to the regular onboard 
IDE-controller of a modern mainboard. This means that the best solution 
is to use a IDE-HDD to save the audiodata from within your recording 
software. The simple presence of the controller (that is used while the 
audiodata is stored on a IDE-HDD) is no problem."

Uh-oh again.  The 7890 is the on-board version of the 2940.  I thought I 
had the xruns pretty much under control with the 2.4 kernel, then I 
picked up a M-Audio Delta 1010LT (I was jonesing for the 8 channels of 
input!).  Ugh.  I can't record more than a few seconds of 8 channel 
input before a 100msec+ xruns brings everything to a halt.  Even 
recording 2 channels won't make it through a 4:00 min song.

So, am I completely hosed with my Adaptec SCSI drive setup?  Anybody 
have any insight into these Adaptec controllers?  I've fussed with the 
setpci latency_timer settings (from Jan Depner's "Installing and 
configuring ALSA, JACK, & Ardour..." web site), but still see long 
xruns.  Trying an IDE drive is not that simple, as I don't have any 
drive slots left in the box (I've got 4 SCSI drives setup as a RAID).  
So, I'd like to exhaust all possibilities before trying new drive 

Any thoughts/ideas/suggestions would be _greatly_ appreciated!



More information about the Linux-audio-user mailing list