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
"As we enjoy great advantages from the invention of others, we should be
glad of an opportunity to serve others by any invention of ours, and
this we should do freely and generously."
Benjamin Franklin, on declining patents offered by the governor of
Pennsylvania for his "Pennsylvania Fireplace", c. 1744
