Experimental Physics and
Industrial Control System

Marty Kraimer <[email protected]> · Mon, 02 Dec 2002 09:11:44 -0600

Eric Norum wrote:

On Wednesday, November 27, 2002, at 03:17  PM, Till Straumann wrote:

Again: IMO, EPICS should have the _full_ range of OS priorities

available.

Part of the job of porting EPICS to a particular OS would be assigning

the actual values of basic EPICS priorities (like

epicsThreadPriorityIocsh, epicsThreadPriorityBaseMin,

epicsThreadPriorityBaseMax...).

It's absurd: I use EPICS on a real-time OS but have no access to the

priorities needed to get real-time performance when I use the

epicsThread API ;-)

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

priority than netTask we got failures.

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.

Is 100 levels not enough? If priorities 91-99 were reserved for

application threads only would it not be possible to do what you need?

I think that it's better to coerce other system tasks into the EPICS

range if appropriate since it makes moving a given EPICS application

from one processor to another so much easier.

Sounds good to me.

I think that the 'base max' (I'm still hoping that someone can come up

with a good name for this) priority level (90, right???) should be added

to epicsThread.h.

Could we just define

static const unsigned epicsThreadPriorityIocsh = 91;

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

epicsThreadPriorityIocsh?

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

I dont see any reason to define epicsThreadPriorityNetworkDaemons. The only

operating system that will currently use it is RTEMS.

Marty

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System