RE: PPMC progress

[John Craddock <johncrad-at-xitech.com.au>]

Ray,
Recently on the RTLinux list there has been a discussion about a latency
problem with Xfree86 and some accelerated graphics cards. Somehow, what you
describe seems to have similar traits. It might be worth having a look at
the RTLinux archives in your quest for solutions. The thread was only very
recent.
Regards
John C

> -----Original Message-----
> From: Ray [rehenry-at-up.net]
> Sent: Monday, December 11, 2000 2:43 AM
> To: Multiple recipients of list
> Subject: Re: PPMC progress
> 
> 
> 
> On Sun, 10 Dec 2000,  Jon wrote:
> > I now have all 3 axes that are supported in my versions of EMC
> > working from encoder input to DAC output.
> 
> Good News.  I'd like to show one running something at NAMES.  
> Let's talk
> off list about this.
> 
> > The crashing problem I had is actually an old one, having
> > something to do with either Linux 2.0.36 or the RT patch
> > and the TkEMC GUI.  I have had a number of versions
> > of EMC later than 15-Mar-2000 that would hang up the
> > XFree86 screen, keyboard and mouse, or the whole
> > system.  I tried running the xemc GUI instead of TkEMC,
> > and it continued to work for about 45 minutes, until I
> > glitched the hardware with an errant scope probe.
> > Ray, do you have any ideas about this?  I'd much
> > prefer to stay with the TkEMC, but if it will only work
> > with 1999 releases of EMC, that is kind of limiting.
> 
> Yes, and I was using a 99 release at NAMES last year and got 
> the same kind
> of lock up a couple times.
> 
> Ho! Wah! (a youpperism who's meaning varries greatly with the 
> inflection
> used to express it.)  And it seems to get worse with the tcl 
> lib that I've
> been building.  I thought that it might be related to the 
> problems with
> mbuff but if you have increased the problems with your 
> additions to 2.0.36
> then it is more fundamental than that.
> 
> I have a very had time believing that Tcl/Tk all by itself 
> can reach in
> and trash the mouse and keyboard IO.  There must be some 
> overlap between
> the EMC code, the tcl interpreter, emcsh, and the commands 
> being passed
> from one end of the programming stack to the other.   
> 
> Another thing that I have noticed, but this is not a hard empirical
> conclusion is that a newly installed EMC does it less 
> frequently than does
> a used system.  Go ahead and laugh and flame but the software seems to
> degrade over many starts.  With the lib work, I've had to 
> reinstall the
> 9-25 bin at least three times or after a few dozen starts, it 
> will hardly
> run cds.ngc at all. 
> 
> I thought for a while that the problem was that when the EMC 
> shut down, it
> left some garbage around.  It will often leave mbuff in the 
> core but that
> is only a post 2.0.37 problem.  Rebooting seems to help some 
> but after a
> bunch of starts and stops, it gets almost impossible to work 
> with.  Almost
> as irritating as BSOD.  I haven't reinstalled the rtlinux 
> only the EMC.
> 
> My plan was to reinstall everything from Mandrake on but I'd 
> like to get
> to the bottom of the real problem rather than just getting a 
> new run at
> it.  Since I have a "cripple" here, I'd like us to study it.  
> But I have no
> clue what to do next.  
> 
> Could someone help with a debug routine that traces the whole system
> through.  I could run it here and post the results for study. 
> Will tried a
> while back with the mbuff problem but I found no real clues 
> from all of
> what he suggested.   As Jon points out below, any debug 
> routine would have
> to save to a fifo during the run 'cause there is no good way 
> back into the
> kernel.  Maybe a network, and I could set up one of those.
> 
> > (I still have the debugging stuff you sent me in June, 2000,
> > but I'm not too sure what good it will do, as the lockups
> > kill the keyboard and mouse.  The caps lock key no longer
> > toggles the caps lock light, and the Ctrl/Alt/Backspace
> > won't kill X.)
> 
> Thanks in advance for your help.
> -- 
> 
> Ray
> 
>