Different behavior of comedi_command under 2.4 & 2.6 based-kernel

[Yoshiya Matsuzaka]

Hello,

While executing a realtime task under kernel 2.6.20.21 patched with RTAI 3.6,
I found that simultaneously executing comedi_command degrades the accuracy of
the RTAI's task-scheduling, causing hundreds of microseconds' jitter. This never
happened under 2.4 based kernel.
Is there any difference in the way COMEDI performs asynchronous acquisition
under 2.4 and 2.6-based kernel? If not, how can I execute the asynchronous
acquisition under 2.6 without interfering with the realtime task execution?

My environment is as follows:
CPU: 3.2 GHz Pentium Pro
RAM: 3.62 GB
kernel: 2.6.20.21 patched with RTAI 3.6
COMEDI & COMEDILIB: 0.7.76 & 0.8.0

Thanks.

Yoshiya Matsuzaka