Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Tue, 18 Mar 2014 17:03:20 +0100

On 18.03.2014 16:47, Brian Bevins wrote:

Is there any way to specify that CA delivery of updates from certain

records should be prioritized over other records on the same ioc?

I've got an application where a bunch of ai's are processed at 10Hz

and some relatively big (for us) waveforms are processed at about

0.3-0.5 Hz. The ioc is not heavily loaded and all record processing

seems to happen in a timely way, but from the client end (EDM) the

"fast" records all pause for ~0.5 sec whenever the waveforms push out

their CA updates.

The ai's are already being processed at a higher priority, but this

doesn't seem to help their updates get pushed out with higher priority.

Is there some tinkering I can do with the priorities of the CA threads

to get what I want? How can I tell which thread will get which record

updates? Is there something more obvious I'm missing?

Thanks,
--Brian

The CA thread pairs on the server (IOC) are created per client.

The client can set the priority as an argument to the

ca_create_channel() call [1].

If the client-set priorities are honored on the server depends on the

server side OS and/or configuration.

On real-time Linux, the MCoreUtils module [2] (EPICS 3.15 only) contains

a rule-based engine to tinker with IOC thread priorities and policies.

Cheers,
~Ralph

[1]

http://www.aps.anl.gov/epics/base/R3-14/12-docs/CAref.html#ca_create_channel

[2] http://epics.sourceforge.net/mcoreutils/

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System