Experimental Physics and
Industrial Control System

Eric Norum <[email protected]> · Mon, 02 Dec 2002 09:45:45 -0600

On Monday, December 2, 2002, at 09:11  AM, Marty Kraimer wrote:

I have mixed feelings. Again in the past when we created tasks with

higher priority than netTask we got failures.

I'm confident that RTEMS has no problems (other than possible CPU

starvation) with running application tasks at an equal or higher

priority than the network tasks.

I do see that it is impossible on vxWorks to create a thread with a

priority < 100. Thus it is not possible to create a thread with

priority > tNetTask.

What to do????

If user really wants a thread with higher priority than tNetTask

he/she could do what Eric suggests and change the priority of > tNetTask.

In fact I plan to commit a change today to run the network tasks at a

priority just less than the lowest-priority scan task. This will make

the scan times much more deterministic.

Could we just define

static const unsigned epicsThreadPriorityIocsh = 91;

And then state that nothing in base has a priority higher than

epicsThreadPriorityIocsh?

I'm not sure that the side issue has been dealt with. I would argue ,

and I think Till would agree, that the IOC shell should also run at a

priority less than the scan tasks to ensure the determinism of the scan

tasks.

If this is not OK I can't think of a better name than
epicsThreadPriorityBaseMax

I'd rather use that name, as poor as it is, than assign any particular

priority to epicsThreadPriorityIocsh.

I dont see any reason to define epicsThreadPriorityNetworkDaemons. The

only operating system that will currently use it is RTEMS.

I agree.

I plan to set the RTEMS network tasks priority to:

epicsThreadGetOssPriorityValue(epicsThreadHighestPriorityBelow(epicsThre

adPriorityScanLow))

unless the application developer specifies otherwise.

--
Eric Norum <[email protected]>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System