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Subject: Re: base max thread priority
From: Eric Norum <eric.norum@usask.ca>
To: Marty Kraimer <mrk@aps.anl.gov>
Cc: "Johnson, Andrew N." <anj@aps.anl.gov>, Jeff Hill <johill@lanl.gov>, Till Straumann <strauman@SLAC.Stanford.EDU>
Date: Tue, 26 Nov 2002 14:50:25 -0600

On Tuesday, November 26, 2002, at 02:25  PM, Marty Kraimer wrote:

At the EPICS meeting last week Till asked:

1) Could we declare a maximum priority for any component of base?
2) Why does iocsh run at epicsThreadPriorityMax?

Brief discussion.

1) sounds like a good request. How about

epicsThreadPriorityBaseMax = 91

2) I will assume that this was done to be like vxWorks, which runs the vxWorks shell at highest priority. If iocsh runs at epicsThreadPriorityBaseMax it seems like it should be OK. If a very high prority application thread uses all the CPU time iocsh can't get control but this is the applications problem.

(2) -- I think we did this to ensure that you could still get some response at the console even if some other task went insane and started gobbling CPU cycles. With a strict priority-based scheduler like RTEMS and vxWorks you'd have no possiblity of dealing with such tasks if the shell were at a lesser or equal priority.

--
Eric Norum <eric.norum@usask.ca>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407


Replies:
Re: base max thread priority Till Straumann
References:
base max thread priority Marty Kraimer

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