RE: ring buffer overflow

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

Hi Hinko,

The EPICS device support keeps a "ring buffer" (FIFO) of callbacks from the driver.  This is used when the records are I/O Intr scanned.  This is intended to buffer callback values in the case when they come in a rapid burst and record processing cannot keep up.  If the callbacks from the driver come faster than the record processing can run, then you will get the message you see when the buffer overflows.  It is probably not a serious error, but you can increase the size of the buffer if needed.  The default size of the buffer is 10 values, but this can be changed on a per-record basis.

How fast is your driver generating callbacks?

Mark



-----Original Message-----
From: tech-talk-bounces@aps.anl.gov on behalf of Hinko Kocevar
Sent: Mon 6/8/2009 1:47 AM
To: tech-talk@aps.anl.gov
Subject: ring buffer overflow
 
Hi all,

I'm creating an EPICS asyn support driver for EPICS base 3.14.10, asyn
4.10 and managed to get it running on the target armel device.
Sometimes after initialization completes I get several messages like these:

...
iocRun: All initialization complete
2009/06/08 06:37:46.774 LIBERA01:SA:SA_MONITOR devAsynUInt32Digital
getCallbackValue error, 1 ring buffer overflows
epics>

What does it mean?

Thank you,
Hinko

-- 
Hinko Kocevar
Technical support engineer
Instrumentation Technologies
Velika pot 22, SI-5250 Solkan - Slovenia
T:+386 5 3352600, F:+386 5 3352601
mailto: hinko.kocevar@i-tech.si

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