Experimental Physics and
Industrial Control System

Brian Bevins <[email protected]> · Tue, 18 Mar 2014 15:50:32 -0400

On 03/18/14 13:00, Ralph Lange wrote:

On 18.03.2014 17:30, Brian Bevins wrote:

The waveforms are soft records that have their buffers filled by

dedicated threads, which then post events to process the records.

I only see the slowdown when a client is connected to the waveforms.

Even with the waveform records processing normally, the "fast"

records update normally as long as no CA clients monitor the

waveforms. I interpreted this to mean that the CA traffic was the

bottleneck, but maybe I'm wrong.

Hmmm... another idea:

Please check that you have no database links that would pull "fast"

and "slow" records into the same lock set.

During record processing, waveforms are put in the CA send queue by

reference, while atomic data is put directly into the queue.

When the low-priority CA send thread later-on copies the data out of

the record into the network buffer, it has to lock the record. (It can

just copy from the queue for atomic data, which does not require

locking.)

Possible effect: if your database has link connections that pull

waveform records and "fast" records into the same lock set, the "fast"

records might block while CA copies data from the waveforms.

Perfectly harmless looking things, like SDIS links pointing to the

same "disable" record, may easily pull far too many records into the

same lock set.

Making this kind of links ".CA" often helps by breaking up the lock

sets without affecting function.

On 03/18/14 13:14, Andrew Johnson wrote:

The IOC shell 'dblsr' command shows you the IOC's lock-sets.

'dblsr * 1' will print all the lock-sets and their members, while 'dblrs
* 2' shows you the links between the records as well. Unfortunately the
output is a bit noisy. You can use a specific record name instead of the
* to see just the lock-set containing that record.

A very good point. I checked all the lock sets and each of my "fast"

records and each of my waveforms is in its own set.

--
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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System