Experimental Physics and
Industrial Control System

Hinko Kocevar <[email protected]> · Fri, 14 May 2010 10:17:45 +0200

Hi Mark,

On 05/13/10 12:16, Hinko Kocevar wrote:

>> devEpics
>>
>>
>> Undid the change that was done in R4-9 with direct calls to dbScanLock and process in the interrupt callback functions. This could lead to deadlocks in some circumstances. The original reason for changing from scanIoRequest to (dbScanLock, process) was because callback values would be lost if the callbacks came so close together in time that the single callback value stored in device support was overwritten before scanIoRequest could process the record. This problem has been fixed by adding a FIFO (ring buffer) to the device support for the scalar interfaces asynInt32, asynUInt32Digital, and asynFloat64. The ring buffer is only created when the record is put into I/O Intr scan, so the storage is not allocated for records that are not I/O Intr scanned. The ring buffer default size is 10 values, but this can be changed on a per-record basis using the dbInfo string "FIFO" with a value such as "100".
>>

I've upgraded the Asyn to 4-10 and I'm performing some tests.
How and where should I set the "FIFO" parameter? In each PV record?

I have several ports started in my IOC and some of them do periodic data
processing on external trigger signal - I/O Intr scanning. It looks like
some more intensive callbacks get all the attention and the slow (low
priority?) so not get serviced at all. Would this ring buffer size be
the solution ?

Is there a global 'ring buffer' for I/O Intr callbacks I need to worry
about - resize that is? My I/O Intr spawned callback rate is more than
15 per second, in different IOC ports/PVs. Looking at the debug output I
see that some callbacks do not get serviced. Only by disabling the port
initialization and processing relaxes the IOC and I/O Intr scanned
callback are processed in timely fashion.

Best regards,
Hinko

-- 
Hinko Kocevar
Technical support software 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

The information transmitted is intended solely for the addressee and may
contain confidential and/or privileged information. Any review, retention,
disclosure or other use by persons other than the intended recipient is
prohibited. If you received this in error, please notify the sender and
delete all copies.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System