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

Subject: Re: Prioritizing Channel Access per Record?
From: Ralph Lange <[email protected]>
To: EPICS Tech-Talk <[email protected]>
Date: Tue, 18 Mar 2014 17:38:28 +0100
On 18.03.2014 17:26, Brian Bevins wrote:
Using client-set priorities occurred to me, but then it seems I would need to write my own client to monitor and display the slow (or fast) records. Standard clients are all pretty much going to use a default priority in ca_create_channel(). If there is an existing general purpose client that allows setting the priorities, I'd love to hear about it. I'm currently using R3.14.12.3 on RTEMS, and I don't yet know if that supports client-set priority. If it does, then writing a little display program might work.

RTEMS uses real-time priorities, so the CA priority will have effect.

IOC-to-IOC connections have a higher CA priority by default (80), which might give you a somewhat indirect influence. (A soft IOC connecting to the "fast" channels will get them with higher CA priority than regular GUI clients or Gateways.)

The 'casr' command on the IOC will list the priorities of all current CA connections.

If I were to switch to rt linux and make use of mcoreutils, it sounds like I would essentially run two virtual iocs on the same machine, one at a higher priority. Is that right?

No.
MCoreUtils uses a hook into the EPICS thread creation mechanism. You specify rules that - by regex-matching on the thread name - directly manipulate priority, scheduling policy, and CPU affinity whenever the IOC starts a thread.

Cheers,
~Ralph


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Re: Prioritizing Channel Access per Record? Brian Bevins
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Prioritizing Channel Access per Record? Brian Bevins
Re: Prioritizing Channel Access per Record? Ralph Lange
Re: Prioritizing Channel Access per Record? Brian Bevins

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