Underruns on Audio CD Burns
I have an interesting problem burning one CD, I keep getting underruns.
I can avoid it by using a low speed burn, or live with it with the
burnfree option, but I don't understand why it occurs.
The system is a P4-2.8G, 1GB memory, 40x CD burner. The O/S is FC1,
latest 2.4.22 kernel, and the burner runs in ide-scsi. The burn was done
as root, no warning messages, nothing else running. After the first bad
burn I checked that DMA and interrupts were enabled on the hard disk,
and set the fifo size to 50MB, larger than the longest track (22MB).
cdrecord is 2.01a31 and I tried the 2.01a19 which comes with FC1.
What I don't understand is why/how there could be an underrun when the
fifo is larger than the track. It almost sounds as if the application
were not filling the fifo before starting the burn, but the minimum fill
was 95%, so that seems unlikely. I looked at the code quickly and saw no
obvious cause for this. I also watched the CPU usage which burning, and
it was always 60-70% idle. Since it ran at RR priority there should be
no issue with CPU performance.
bill davidsen <firstname.lastname@example.org>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979