Dear Ralph,
I make a correction.
> What I wanted to do was to give "CAS-client" a priority
> higher than that of "scan-0.1" because commands sent from
> a CA client to an IOC start to be lost when the number of
> records being processed with the SCAN value of ".1 seconds"
> was increased.
The problem was not loss of CA messages but some funny
behavior of the device under EPICS control. I made many
mistakes since I'm now very impatient and confused because
the deadline is approaching very close.
To all.
I apologize to all of you if "you" in Ralph's mail does
not mean me.
J.Odagiri at KEK in a hurry
----- Original Message -----
> Dear Ralph,
>
> I assume that "you" means me in your message because I
> triggered this chain of e-mails. If not, please just ignore
> this e-mail.
>
> (I know "you" can mean unspecified persons in English.)
>
> What I wanted to do was to give "CAS-client" a priority
> higher than that of "scan-0.1" because commands sent from
> a CA client to an IOC start to be lost when the number of
> records being processed with the SCAN value of ".1 seconds"
> was increased.
>
> But now I understand that the problem of mine is not an
> issue of priorities of threads but an issue of something
> else.
>
> (I think default priorities of the EPICS IOC threads
> are well-chosen as you mentioned in a previous e-mail.)
>
> I do not want to choose multiple IOCs solution because
> I want to keep the system as simple as possible.
>
> The value of PRIO field is irrelevant because I do not
> rely on callback threads in my device support.
>
> I can not choose multiple parallel callback solution
> because my system is single-CPU system.
>
> I now suspect that the origin of my problem is not on
> IOC-side but on a custom device-side being controlled
> by the IOC.
>
> Lots of thanks anyway for your detailed comments and
> advice.
>
> Best regards,
>
> J.Odagiri at KEK
>
>
> ----- Original Message -----
> > 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
> >
>
>
>
- References:
- Usage of an EPICS word jun-ichi.odagiri--- via Tech-talk
- Re: Usage of an EPICS word Mark Rivers via Tech-talk
- Re: Usage of an EPICS word Ralph Lange via Tech-talk
- Re: Usage of an EPICS word jun-ichi.odagiri--- via Tech-talk
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