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Subject: RE: EPICS base V4: iocCore database
From: "Kenneth Evans, Jr." <evans@aps.anl.gov>
To: 'Jeff Hill' <johill@lanl.gov>, 'Marty Kraimer' <mrk@aps.anl.gov>
Cc: 'Andrew Johnson' <anj@aps.anl.gov>, 'Bob Dalesio' <ldalesio@lanl.gov>, 'Ralph Lange' <Ralph.Lange@mail.bessy.de>, 'Eric Norum' <norume@aps.anl.gov>, 'Benjamin Franksen' <benjamin.franksen@bessy.de>, 'Ned Arnold' <nda@aps.anl.gov>, 'Matej Sekoranja' <matej.sekoranja@ijs.si>
Date: Wed, 23 Feb 2005 11:31:54 -0600
All,

My two bits in response to what Jeff said about the Gateway:  As he said,
the Gateway appears to work quite well using GDD.  Our main Gateway handles
on the order of 20,000 events per sec 24/7 without using much CPU.  I can
get it up to 200,000 Hz.  It ran for a period of over 3 months (6-11-04 to
9-27-04) without being restarted or restarting itself.  This indicates
memory fragmentation is not a critical problem.

The problem with GDD is rather that it is hard to understand and hard to
work with.  It is hardly KISS.  It is daunting for new developers that try
to use CAS.  Because of the complexity, it has perpetually been the cause of
errors that take much time to track down and fix.  

But the fact is that these errors are pretty much fixed at this point.
There is this rule about not changing a working program.  Rewriting Channel
Access to be threaded caused about two years of intensive work, much of it
debugging on my part, before it became stable again around 3.14.6.  We (I at
least) really do not want that to happen again.

Don't interpret this as meaning I like GDD, however.  I don't.

	-Ken



References:
RE: EPICS base V4: iocCore database Jeff Hill

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