Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0

[Fernando Pablo Lopez-Lezcano]

On Mon, 2004-10-25 at 20:01, Lee Revell wrote: 
> On Mon, 2004-10-25 at 20:40 +0100, Rui Nuno Capela wrote:
> > OTOH, jackd -R xruns are awfully back, even thought I (re)prioritize the
> > relevant IRQ thread handlers to be always higher than jackd's.
> 
> Actually they should be lower, except the soundcard.  I was only able to
> get the xrun free behavior of T3 by setting all IRQ threads except the
> soundcard to SCHED_OTHER.  Especially important was setting ksoftirqd to
> SCHED_OTHER, this actually may have been the only one necessary.
> 
> The relative priorities of jackd and the soundcard irq do not matter as
> these two should never contend (aka they are never both runnable at the
> same time).

What happens when one is blessed with a laptop where everything is
sharing an interrupt?

$ cat /proc/interrupts
           CPU0
  0:    2372239          XT-PIC  timer  0/72239
  1:       5362          XT-PIC  i8042  0/5362
  2:          0          XT-PIC  cascade  0/0
  8:          1          XT-PIC  rtc  0/1
  9:     616176          XT-PIC  acpi, uhci_hcd, uhci_hcd, uhci_hcd,
eth0, yenta, yenta, Intel 82801CA-ICH3, radeon@PCI:1:0:0  0/16176
11:         37          XT-PIC  sonypi  0/35
12:      28392          XT-PIC  i8042  0/28392
14:      21078          XT-PIC  ide0  0/21078
15:        472          XT-PIC  ide1  0/472
NMI:          0
LOC:          0
ERR:          0
MIS:          0

I'm running U10.3 and I'm consistently seeing xruns when Jack clients
start and stop, something I would not see before (I have not tried the
latest V series yet). I have tried changing the priority of IRQ9 and the
scheduler but I still see the xruns. Yesterday I tried enabling
preempt_thresh to a low value but did not see hits when the xruns
occurred. Maybe I'm missing something I need to do...

-- Fernando


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