Hi,
Can anyone explain the following:
I'm running rtlinux 2.2.13 on a PIII 450 (I was very pleased with the ease of
installation and use!).
A test program periodically flips the parallel port bits, thus giving a
square-wave output on an oscilloscope (periodicity 25000, or 25 microsec).
Jitter on the square wave edge is about 2.5 microsec full-width on the scope.
No amount of cpu hogging changes this, as expected.
But if I run a PCI bus hog, the jitter increases by a factor of 4-5, to over 10
microsec fw on the scope. I hog the bus by performing continuous 100k DMA
transfers on the pci bus from vme memory into pc memory via an SBS model 617
pci-vme bridge.
I know little about pci buses...what's getting preempted by the bus hog? a
clock? memory? parallel port? something else?
(please respond to [EMAIL PROTECTED])
Sincerely,
Elliott Wolin
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