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

Subject: record ring buffer flushing
From: Hinko Kocevar <hinko.kocevar@i-tech.si>
To: EPICS tech-talk <tech-talk@aps.anl.gov>
Date: Thu, 26 May 2011 11:05:55 +0200
Hi all,

We are running EPICS 3.14.10 on ARM based system. Our device driver is using asyn driver.

There are several records that are processed on I/O intr SCAN. Sometimes the I/O rate is quite high and the system load (CPU) goes over the top, with high (> 3.0) loadavg. When this happens IOC is sluggish to respond to any CA requests.

Even if we manage to 'disable' the processing inside the device driver (in terms that no new data is written to record buffers, I/O intr SCANing still active), it takes quite some time to process all the pending requests already in the ring buffers for the corresponding record.

Only then can we successfully use the CA to set/get any other PV on the IOC, and not worry about the delayed response and/or timeouts.

Is there a way to tell IOC or a PV record to forget the pending events/requests in its ring buffer (eg. some kind of flush)?

This way we could be sure that the IOC will be responding in timely fashion, when we try to access some PV, and avoid waiting for the ring buffer to empty by itself..

Has anyone dealt with similar situation?

Any comments and suggestions are welcomed!


Thank you,
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: hinko.kocevar@i-tech.si

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Replies:
RE: record ring buffer flushing Mark Rivers

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