RE: Prioritizing Channel Access per Record?

[Mark Rivers <rivers@cars.uchicago.edu>]

Are you certain that it is the CA update of the waveform records that is slowing it down, and not the record processing?  if your waveform records are using synchronous device support and they take a long time to process that can slow down all other records.  What type of device support do your waveform records have, synchronous or asynchronous?

Mark


-----Original Message-----
From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Brian Bevins
Sent: Tuesday, March 18, 2014 10:47 AM
To: EPICS Techtalk
Subject: Prioritizing Channel Access per Record?

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

-- 
Brian S. Bevins, PE
Computer Scientist / Mechanical Engineer
Thomas Jefferson National Accelerator Facility

      "The urge to save humanity is almost always only a false-face
       for the urge to rule it."
                                      -- H. L. Mencken