Dear Odagiri san,
* Is your Linux is a real-time kernel?
* which way do you communicate with many PSC? A dedicated network
connection? The same (as your IOC) ethernet connection? USB? FireWire?
* do you have a specific kernel driver for this connection?
We've had some discussion on this issue on the Core-talk, you may see
the solution which you want to find in there
https://epics.anl.gov/core-talk/2021/msg00143.php
HTH,
Han
On Sat, Mar 27, 2021 at 12:36 AM jun-ichi.odagiri--- via Tech-talk
<tech-talk at aps.anl.gov> wrote:
>
> Dear William,
>
> Thank you for your comment,,, but sorry, I did not understand
> the meaning of the "multiple callback threads" solution.
> Would you tell me about it a little bit more in detail?
>
> Best regards,
>
> J.Odagiri at KEK
>
>
> ----- Original Message -----
> > A few other ideas is that you can try multiple callback threads or
> > splitting into multiple IOCs.
> >
> > On Sat, Mar 27, 2021, 2:32 AM jun-ichi.odagiri--- via Tech-talk <
> > tech-talk at aps.anl.gov> wrote:
> >
> > > Dear Ralph
> > >
> > > Thanks for your reply.
> > >
> > > > Changing priorities of callback, driver or communication threads
> with
> > > > respect to database processing.
> > > >
> > > > Which is exactly what your question is about.
> > >
> > > I got it. Thanks!
> > >
> > > > Why do you want to change the priority of "CAS-TCP"? Note that
> this is
> > > not
> > > > a "general purpose thread", but one of the core threads of the
> Channel
> > > > Access server.
> > >
> > > Here is the reason.
> > >
> > > An IOC controls many power supplies of something. The IOC is polling
> the
> > > status of the power supplies at a SCAN rate of 0.1 seconds. When the
> > > number of the power supplies increases, the IOC starts to lose
> commands
> > > sent from an CA-client. I thought that the problem would be solved
> if
> > > I give the "CAS-TCP" a priority which is higher than that of "scan-0.
> 1".
> > >
> > >
> > > But, on the second thought, I realized that there is no need to do
> that
> > > because the commands sent from the CA-client will be queued on the
> IOC-
> > > side.
> > > As far as some time is left for the "CAS-TCP" to run, the loss of
> > > commands
> > > should not occur.
> > >
> > > Am I right?
> > >
> > > I guess the origin of the problem would not be an issue of priority
> but
> > > an issue of throughput. So, I decided to solve the problem by
> improving
> > > the efficiency of the polling of the status of the power supplies.
> > > Fortunately, there is a way to do that.
> > >
> > > > The default priorities of the EPICS IOC threads are well-
> chosen.
> > > They
> > > > have been proven to ensure reliable IOC operation and
> communication,
> > > in
> > > > many installations, under a variety of circumstances.
> > >
> > > I am really aware of this. That is the reason why I noticed my
> > > misunderstanding
> > > of the situation.
> > >
> > > Best regards,
> > >
> > > J.Odagiri at KEK
> > >
> > >
> > > ----- Original Message -----
> > > > On Fri, 26 Mar 2021 at 08:09, jun-ichi.odagiri--- via Tech-talk <
> > > > tech-talk at aps.anl.gov> wrote:
> > > >
> > > > > Here is my question.
> > > > >
> > > > > Can I change the priority of "CAS-TCP" thread and "scan-10"
> > > > > thread so that the former is given a higher priority than
> > > > > that of the latter without modifying any source files in
> > > > > base?
> > > > >
> > > > > Does the site you guided me to answer the question?
> > > > >
> > > >
> > > > As per the README of the MCoreUtils, one of its features is
> > > >
> > > > Changing priorities of callback, driver or communication threads
> with
> > > > respect to database processing.
> > > >
> > > > Which is exactly what your question is about.
> > > >
> > > > The MCoreUtils facility allows rule-based manipulation of thread
> > > > properties, so that things like changing a priority will apply to
> all
> > > > threads with a name matching a specific pattern, whenever they
> will be
> > > > created on that IOC.
> > > >
> > > > Why do you want to change the priority of "CAS-TCP"? Note that
> this is
> > > not
> > > > a "general purpose thread", but one of the core threads of the
> Channel
> > > > Access server.
> > > > (From the MCoreUtils documentation:)
> > > > Warning
> > > > The default priorities of the EPICS IOC threads are well-
> chosen.
> > > They
> > > > have been proven to ensure reliable IOC operation and
> communication,
> > > in
> > > > many installations, under a variety of circumstances.
> > > > Manipulating the real-time properties, especially scheduling
> > > policies
> > > > and priorities, may have unwanted side effects. Use this feature
> > > sparingly,
> > > > and test well.
> > > >
> > > > Cheers,
> > > > ~Ralph
> > > >
> > >
> > >
> > >
> >
>
>
- Replies:
- Re: Changing EPICS general Purpose Thread's Priorities jun-ichi.odagiri--- via Tech-talk
- References:
- MRF kernel module, failed to map BARS GAGET Alexis via Tech-talk
- Re: MRF kernel module, failed to map BARS Michael Davidsaver via Tech-talk
- RE: MRF kernel module, failed to map BARS GAGET Alexis via Tech-talk
- Changing EPICS general Purpose Thread's Priorities jun-ichi.odagiri--- via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities Jeong Han Lee via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities jun-ichi.odagiri--- via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities Ralph Lange via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities jun-ichi.odagiri--- via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities William Layne via Tech-talk
- Re: Changing EPICS general Purpose Thread's Priorities jun-ichi.odagiri--- via Tech-talk
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