Re: Back to FIFO overflows

Frank,

Tried the patch.  Only real change in the symptoms is that 
the programs seem to run longer before the fifo overflows.
The two runs I've managed so far lasted about 6 hours. If
I had not seen the failure before I would suspect say that
things were working Ok after an hour or so.  If the test 
I'm doing now lasts more than 5 hours or so I'll probably
try to just live with it. May have to figure out the RTAI
stuff after all :-).

I was hoping the boards would just plug and play.  They seem
to work OK at 1000 scans per second. They start to get the
fifo overflow at 2K and above.  The PCI-DAS1602/16 has a 512
sample FIFO. If I have set things up correctly there should
be a half-full interrupt every 4 millseconds.  At each interrupt
there are 256 samples to read. Hard to imagine a 4 to 8 millisecond
interrupt latency but that seems to be the case. I tried the 
RTAI latency_calibration (24.1.8) and it gave a maximum latency 
of 11554 ns and an average of 2377 ns.

I'll try to look at the autocalibration features in the next 
day or two. I need to get the collection system up to 4K first
for a test in Estonia later this month.

John

> > I'd like to know if anyone else can reproduce the problem.
> > I'm using comedi-0.7.66 and comedilib-0.7.19 and have an
> > RTAI installed in a 2.4.17 kernal. Not really using the
> > RTAI stuff at the moment.
> >
> 
> I have heard at least one other report of similar problems.  I took
> a peek at Warren Jasper's driver, and his interrupt handler clears
> the amcc s5933 interrupt in a slightly different order than I do. =20
> Would you try the patch below (it is against the current cvs)?
> Also, a test of comedi_calibrate using the current cvs of comedi
> and comedilib would be appreciated if you are interested in the
> board's autocalibration features.
> 
> It might not be a driver problem though, since the board has
> a relatively small fifo with no DMA, and there are no guarantees=20
> on interrupt latency in vanilla Linux.
> 

Received on 2003-01-13Z15:16:24