Subject: Re: [linux-audio-user] Ardour, Jack, and 2.6 kernels + XRuns with the Audiophile 24/96 M-Audio
From: Joel White (cv223_AT_comcast.net)
Date: Tue Jun 01 2004 - 06:00:47 EEST
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
(http://www.staudio.de/kb/english/conflicts/):
"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
configurations.
Any thoughts/ideas/suggestions would be _greatly_ appreciated!
Thanks,
Joel
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