Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Tue, 24 Aug 1999 17:01:02 -0600

Dale,

>
> I have a problem w/ our beamline ioc in that it seems only able
> to keep up
> a connection w/ one workstation at a time. If I try to connect
> two clients
> at once, the connections are lost after a minute or two, and I can't
> thereafter ping the ioc. I don't get any error msgs at the
> console. One odd
> thing I noticed is that if I then try to ping the ioc I get an
> increase in
> the "echo" entry in the icmpstatShow output, but a timeout from the other
> end, i.e. it thinks it is responding. Does this problem sound familiar to
> anyone? Any suggestions?

It sounds like some high priority task is preventing the vxWorks "netTask"
from running. Run the vxWorks "spy" utility from the console terminal of
your IOC to find out is this is your situation.

This may be the bug that I reported some weeks back. If so, you should
see these symptoms:

o A CA client task is in a tight loop which is periodically elevated by
priority inheritance to the same priority level as the vxWorks "netTask",
and this task is using all available CPU at its priority level.

o In an IOC the CA client tasks are usually "DB CA link" tasks, sequencer
tasks, or possibly also some site specific CA client application tasks.

I discovered this bug during testing, but have not seen it occur in any
of our operational systems.

A patch for this bug has been applied to the R3.13.1 CVS branch at APS, but
this version is, I suspect, not yet available for distribution.

Jeff

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System