[linux-audio-user] xruns from ardour + softsynths

[Atte André Jensen]

Hi

I played a bit with ardour to the extend that I ended up with 12 tracks 
of backing vocals (playing at the same time) + a lead vocal + some talk 
+ zynaddsubfx (running two pads + bass) + specimen (drums) + ams (lead) 
+ seq24 for midi.

This is too much for my setup, I get audible xruns every now and then 
(just after loading the song often, after a while about every minute, 
with no window activity) and qjackctl reports them all the time. However 
the cpu usage is below 50% so I'm led to believe that with some fine 
tuning it should be possible.

My computer is a Pentium M 1.6 w 1G ram, 100G 7200 RPM HD running 
xubuntu/dapper/6.06 and I use the (I know shitty) onboard i8x0 . 
Basically all I did was:

echo @audio - rtprio 99 >> /etc/security/limits.conf
echo @audio - memlock 250000 >> /etc/security/limits.conf
echo @audio - nice -10 >> /etc/security/limits.conf

I think my soundcard works at 48000 hz, but I run jack at 44100 because 
of previous (now resolved) problems with zynaddsubfx. Could this be the 
cause of my problems?

hdparms says:
root at ajstrup:~# hdparm /dev/hda
/dev/hda:
  multcount    =  0 (off)
  IO_support   =  0 (default 16-bit)
  unmaskirq    =  0 (off)
  using_dma    =  1 (on)
  keepsettings =  0 (off)
  readonly     =  0 (off)
  readahead    = 256 (on)
  geometry     = 16383/255/63, sectors = 195371568, start = 0

And:
root at ajstrup:~# cat /proc/interrupts
            CPU0
   0:    1435743          XT-PIC  timer
   1:       3861          XT-PIC  i8042
   2:          0          XT-PIC  cascade
   3:      28534          XT-PIC  irda0
   7:          0          XT-PIC  parport0
   8:          3          XT-PIC  rtc
   9:     916321          XT-PIC  acpi
  11:    2391090          XT-PIC  uhci_hcd:usb1, uhci_hcd:usb2, 
uhci_hcd:usb3, ehci_hcd:usb4, ath0, yenta, Intel 82801DB-ICH4, yenta, 
eth0, radeon at pci:0000:01:00.0
  12:       2488          XT-PIC  i8042
  14:      82500          XT-PIC  ide0
  15:      98767          XT-PIC  ide1
NMI:          0
LOC:          0
ERR:          0
MIS:          0

This is how jackd is setup (run through qjackctl):
atte at ajstrup:~$ cat .jackdrc
/usr/bin/jackd -v -R -P65 -dalsa -dhw:0 -r44100 -p256 -n2 -S

Any ideas?

-- 
peace, love & harmony
Atte