Extended Scheduling Latency on LinuxPPC 2.4.10

Banks, Kelly kelly.banks at gilbarco.com
Wed Feb 27 08:21:27 EST 2002

Running LinuxPPC 2.4.10 in an MPC860 board, I am experiencing an extended
period of time when the kernel seems to be 'out to lunch'.

The system receives a periodic poll request over SCC2 & is designed to
respond to the poll in a timely fashion.

Occasionally, the system appears to 'hang' for a period of time from between
2 & 8 Seconds.  During this delay, poll requests seem to be queued into
SCC2's input buffer because, eventually, the system comes back to life &
responds to each poll request received.

I am searching through system & driver interrupt routines looking for a
potential extended processing loop but so far, it has been to no avail.

The 2.4.10 low-latency patch has been ported into the system (successfully,
I think), but the problem still exists.

Any guidance which you may be able to provide would be greatly appreciated.


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