[ardour-dev] Ancient history? - Problem identified

cv223 at comcast.net cv223 at comcast.net
Thu Nov 11 09:38:49 PST 2004

A few days ago I posted the following message about tracking down xruns using Ardour to record to a SCSI Raid0.  At the end of the message, I asked whether anyone had any ideas about why commenting out a single line in streamview.cc (which at the very least eliminates updating the "progress" rectangles during recording) completely eliminates my xrun problem, in a rather dramatic fashion (dozens of xruns per min to none).  Since I got a goose egg in response, I thought I would try again because I've run out of things to test and don't know where to look next.  

Basically, how can display updates in Ardour during recording cause xruns with writes to the hard drives?

Since this problem doesn't seem to be common, it seems that it has more to do with my system/hardware configuration than with Ardour/jack.  But what, I don't know.

Any suggestions would be greatly appreciated.  Thanks for your time.

-------------- Original message -------------- 

> (Note that I didn't write "Problem solved" - I don't know how to solve 
> it, besides a hack described below) 
> About a week ago, I posted a message asking about possible reasons why 
> xruns seen using 0.9beta11.2 when recording to a SCSI Raid0 went away 
> with 0.9beta12 (on a 2.4.23 kernel). Paul took pity on my poor, 
> tormented soul and let me have cvs access (thanks again, Paul!) so I 
> could try and track down the problem. I went through a number of old 
> cvs versions by the dates of "CVS commit" messages to the ardour-dev 
> list (not sequentially - I don't have _that_ much time!) and found the 
> smoking gun to be on May 7, 2004, when Jesse Chappell committed code to 
> put waveforms into regions while recording. That code pointed out where 
> the problem was. 
> To make a long story somewhat shorter, it turns out that on my system, 
> updating the regions during recording (even with "Follow playhead" 
> turned off) generates xruns when the SCSI Raid is written to (i.e., 
> xruns occur when the drives chirp). Specifically, if I comment out line 
> 700 in streamview.cc (this is in routine StreamView::update_rec_box() 
> in 0.9beta19): 
> // gtk_canvas_item_set (rect, "x2", xend, NULL); 
> and run Ardour with the Display Option "Show waveforms while recording" 
> turned off, I get no (zero!) xruns while recording to the SCSI Raid, 
> where before I got > 25 per 1 minute of recording. Of course, I don't 
> get the pinkish boxes growing across the screen, but I can live with that. 
> If I don't comment out that line, I get just as many xruns on the newer 
> versions of Ardour as before - I hadn't tried turning "Show 
> waveforms..." off before I started on my cvs quest. I guess I thought 
> the waveforms during recording were too cool. 
> Turning on the "Show waveforms..." still generates about 3 xruns per 
> minute of recording, so I still don't know what's going on there (other 
> gtk canvas access, perhaps?). Also, running under the 
> 2.6.9-rc2-mm4-VP-S7 kernel still generates a handful of xruns per minute 
> on either Raid or IDE drives even with the above hack, so something 
> different still seems to be happening with that kernel. I'll stick with 
> 2.4.23 for now. 
> If anybody has any ideas about what may be going on (how gtk canvas 
> access + SCSI Raid writes = xruns), I'm still curious. Also, I'm 
> willing to try additional tests, if it would be helpful. 
> BTW, this is with gtk+ version 1.2.10. 
> Thanks for your time, 
> Joel 
> _______________________________________________ 
> ardour-dev mailing list 
> ardour-dev at lists.ardour.org 
> http://lists.ardour.org/listinfo.cgi/ardour-dev-ardour.org 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ardour.org/pipermail/ardour-dev-ardour.org/attachments/20041111/5dff288f/attachment-0002.htm>

More information about the Ardour-Dev mailing list