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<== Date ==> <== Thread ==>
Subject: Re: Usage of an EPICS word
From: Ralph Lange via Tech-talk <tech-talk at aps.anl.gov>
To: EPICS Tech Talk <tech-talk at aps.anl.gov>
Date: Mon, 29 Mar 2021 09:38:37 +0200
So, coming back to what (I think) was the original question:
How to change the priority of the general purpose callback threads (named "cb...") to be higher than a periodic scanning thread?

You don't have to. Use the PRIO field.
There are three (sets of) general purpose callback threads, related to the three values of the records' PRIO field: Low, Medium and High.
Their priorities are designed to be lower than all periodic processing (Low), halfway between the slow and the fast periodic processing (Medium) and higher than all period processing (High). For each record, the thread used for callback processing is selected based on the setting of its PRIO field.
On multi-CPU systems, you can also enable multiple parallel callback threads (e.g., one per CPU) to boost the callback and 'I/O Intr' processing power of your IOC.

Only if these mechanisms show not being sufficient for your application, additional steps need to be taken. In most cases, I would assume further parallelization (splitting up the application to multiple IOCs, adding more CPU power) to be more efficient than tuning priorities.

Cheers,
~Ralph

Replies:
Re: Usage of an EPICS word jun-ichi.odagiri--- via Tech-talk
References:
Usage of an EPICS word jun-ichi.odagiri--- via Tech-talk
Re: Usage of an EPICS word Mark Rivers via Tech-talk
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