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<== Date ==> <== Thread ==>

Subject: Re: ring buffer overflow
From: Hinko Kocevar <[email protected]>
To: Mark Rivers <[email protected]>
Cc: [email protected]
Date: Mon, 08 Jun 2009 15:39:00 +0200
Mark Rivers wrote:
> 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.
> 

OK. Thank you for explaining this.

> How fast is your driver generating callbacks?

The fastest callback is issued several times per second (not more then
~10 times). My records are mostly I/O Intr scanned, with one additional
thread that tries to update a single record also 10 times per second.

For now ring overflows appear only now and then and if they keep
appearing I'll try to increase the buffer!

Thank you,
Hinko

> 
> Mark
> 
> 
> 
> -----Original Message-----
> From: [email protected] on behalf of Hinko Kocevar
> Sent: Mon 6/8/2009 1:47 AM
> To: [email protected]
> 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: [email protected]

http://www.i-tech.si - When your users demand stability


References:
ring buffer overflow Hinko Kocevar
RE: ring buffer overflow Mark Rivers

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