SCHED_ULE problem: slow single processor, realtime prio vs network stack

[Andrew Reilly]

On Thu, Aug 28, 2008 at 05:18:04PM +1000, Andrew Reilly wrote:
> Hi Jian,
> 
> On Thu, Aug 28, 2008 at 03:01:59PM +0800, 邱剑 wrote:
> > I found the network interrupt thread might take too long to run if
> > net.isr.direct=1
> > 
> > I suspect your problem might be because the network kernel thread spend so
> > long time that the sound interrupt could not find time slot to process.
> 
> That sounds like what I think is happening, but I'm still
> curious about why the same network stack manaages to be
> interrupted by the audio driver when running the 4BSD scheduler,
> but not the ULE sheduler.
> 
> > You might just try to turn netisr off when running ULE
> > 
> > sysctl -w net.isr.direct=0
> 
> I'll give that a try, as soon as possible.

As promised to Jian, here's my report on how or whether that
helped: no.  If anything, it seemed to make the network-induced
breakup of the audio timing a little worse, but I did no
measurements to verify that impression.  Thanks for the
suggestion, though.

Cheers,

Andrew