Experimental Physics and
Industrial Control System

Simon Reiter <[email protected]> · Wed, 31 Jan 2018 22:26:36 +0100

> On Jan 31, 2018, at 19:18, Benjamin Franksen <[email protected]> wrote:
> 
> Interesting. That confirms my suspicion that this is a problem in base,
> not the sequencer; my guess is that any fast enough sequence of ca_put
> operations on the same PV exhibits this problem (on this architecture).
> 
> Just a blind guess: could it be something about fast mutexes / spin
> locks and how these are implemented for linux-ppc? I am not using these
> in the sequencer, but they are used inside EPICS base (they have been
> introduced in 3.15 or 3.16).
> 
> Another guess: wasn't there a problem report regarding put_notify a
> while ago? Perhaps this is related.
I am not a software expert and I am not familiar with this.

> Do we have tests in base for CA clients? If so, it might be possible to
> adapt such a test so that it rapidly issues ca_put calls (with callback)
> to the same PV and then see if camonitor sees all the events it should see.
If you tell me, how I can test this for ppc, let me know and I will try to analyze it.

> Another angle that could be involved: does the sequencer program run on
> the same IOC that serves the PV or a different one?
The IOC provide the sequencer and the PVs. I guess, if the PV would be provided
by a different IOC, this observation would be worse, right?

Best regards,
Simon

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System