Experimental Physics and
Industrial Control System

"Dale L. Brewe" <[email protected]> · Fri, 09 Apr 1999 17:22:49 -0500

Alan 
I'm willing to believe I've got something configured wrong, but so far I don't
see any likely things to change. Unix connections to the same iocs have no
problem. Either que_get/do_get batch processing or individual cache-based calls
seem to work more than adequately for my purposes, after the first connection.
Mark Rivers suggested changing capendio and/or capendevent, but I don't see how
I might have access to these parameters thru the sca library.
Dale
At 02:49 PM 4/9/99 , Alan Biocca wrote: 
>
> Chris Timossi will likely comment further re NT specifics, but just to give a
> reference point, these functions make 7,000 successful connections in
> something less than 2 seconds from Unix on an old Sparc 2. It is important to
> queue all the requests before processing them, do not do them one at a time.
> (ie queue everything then one do_get). The interfaces in the underlying
> Channel Access are significantly optimized for batch processing and SCA uses
> this. In addition, single requests cause a flurry of packets on the network
> that can cause tinygrams to impact network performance for hosts and network
> neighbors without getting much work done.
>
> That having been said, 250-300 msec sounds slow even for individual requests.
> Possibly a configuration problem.
>
> -- Alan K Biocca
>
> At 09:51 AM 4/9/99 -0500, Dale L. Brewe wrote:
>>
>> I've been using the Simple Channel Access libraries under NT, and have
>> noticed that the time to make an initial connection is quite long. For
>> example, using the routine cache_getbyname, it takes about 45sec to get 140
>> values initially (~0.33sec/value). I've also tried the batch routines
>> que_get and do_get, with a marginal improvement (to ~0.25sec/value), which
>> is still pretty difficult to live with. Can anyone tell me if they have a
>> similar experience? Is this an inherent limitation of these
>> functions/library, or is it possible to improve the performance? My ioc
>> uses epics 3.13beta11 and my client (based on LabVIEW) has used sca3.dll
>> and ca.dll for 3.13.0 and previous versions.
>> Thanks
>> Dale Brewe
>


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Dale L. Brewe     PNC-CAT/U. of Washington
 ph: 630 252 0582         fax: 630 252 0580
 Mail:
 APS/Argonne National Laboratory
 Bldg 435E sector 20
 9700 S. Cass Ave.
 Argonne, IL 60439
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System