[linux-audio-dev] HELP:porting linux audio driver to RTLinux(rtlinux core driver)

[Jan Depner]

On Fri, 2005-04-08 at 14:50, Jack O'Quin wrote:
> Jan Depner <eviltwin69 at cableone.net> writes:
> 
> > On Fri, 2005-04-08 at 12:37, Lee Revell wrote:
> >> Personally I think you're wasting your time.  Ingo's RT preempt patches
> >> let you do hard realtime with Linux using the existing driver base.
> 
> >     I'm not sure why he's trying to do this because for audio the
> > latest patched kernels appear to be more than adequate.  That said,
> > I don't think you can get a guaranteed 15 microsecond interrupt
> > response with anyone's patches to the standard kernel.  I wouldn't
> > call what we have now hard real-time.  More like soft real-time.
> > Maybe when MontaVista gets done...
> 
> Agreed.  
> 
> The Linux kernel will always be "soft" realtime.  They can never
> *guarantee* specific interrupt response latencies, because too much
> kernel code can come along later and mess it all up by disabling
> interrupts or holding locks.
> 
> What many people overlook is that for most practical purposes, soft-RT
> is what they really want.  Hard-RT is only appropriate for a few
> specialized imbedded systems.
> 
> Thanks to the hard work of Ingo, Lee and many other folks, recent
> Linux kernels provide excellent soft-RT, right out of the box.  With
> Ingo's RT preempt patches, the results are world-class.  There will
> always be "two steps forward, one step back" regressions, but those
> fixes keep getting migrated into the base kernel, and the general
> trend is quite encouraging.

    Please, don't think I was being disparaging.  I am absolutely
thrilled with the kernel work that has been going on.  This thing
rocks!  The last I heard (from contractors working for us who were doing
soft real-time on - shudder - Windoze) M$ can only get you to about 30
milliseconds.

Jan