Re: [linux-audio-user] Re: favorite window Manager for making music?

On Sat, 2006-02-25 at 20:11 -0500, Lee Revell wrote:
> On Wed, 2006-02-22 at 21:02 -0600, Jan Depner wrote:
> > On Tue, 2006-02-21 at 22:27 -0500, Lee Revell wrote:
> > > On Tue, 2006-02-21 at 19:16 -0800, Mark Knecht wrote:
> > > > Just speaking logically, if badly written apps can cause a real-time
> > > > kernel to have some xruns, then isn't it true that a badly written WM
> > > > could do the same thing?
> > >
> > > When I say badly written apps I am taking about the JACK client's
> > > processing thread. These xruns are not caused by the kernel. If a JACK
> > > client sleeps in the process() callback or tries to do 10ms worth of
> > > work with a 5ms deadline then xruns are inevitable, the best RTOS in the
> > > world will not help you.
> > >
> >
> > Yes, it will. In VxWorks, if my interrupt is higher priority than
> > whatever the application is doing then the application will be
> > interrupted. Period. That is hard real-time.
> >
>
> The -rt patch works exactly the same way. The audio interrupt will fire
> and interrupt JACK but you'll still get an xrun if you tried to do 10ms
> worth of processing with a 5ms deadline, because the data won't be
> ready.
>
> I think we might be talking past each other - unless you are asserting
> that in VxWorks, I can try to do 10ms of work in my process() callback
> when the deadline is 5ms away and somehow not get an xrun.
>

    You can always *try* to to do 10ms of work in a 5ms slice but it
won't work ;-) I think you're right. I'm talking about the OS as a
whole and you're talking about the application as a single entity. The
application can definitely screw itself. I was thinking in terms of one
application screwing up another one.

-- 
Jan 'Evil Twin' Depner
The Fuzzy Dice
http://myweb.cableone.net/eviltwin69/fuzzy.html
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