itsy bitsy Unix - test-drb@ccmp.vtda.org

18 Mar 2005

...
 From: "Eric Smith" <eric at
brouhaha.com>

Paul wrote:
  all too often, priorities
 are used to hide the fact that the builder didn't analyze the job
 sufficiently, and simply hacked the priorities until things seemed to
 work in test. 
True.  You wouldn't believe how many times I've seen other engineers
trying to set the priority of their task higher than those of other
tasks just because they have some vague idea that their task is
"important", rather than any understanding of actual relationships between
the tasks.

A good rule of thumb is that in the absence of a rational basis for
one task having a higher priority than another, all tasks should have
the same priority.  Far too often a person's intuitive idea of what
the relative task priorities should be is wrong.

Eric

Hi
 If it is important enough to need immediate attention,
it should be interrupt driven and not a general task.
Many confuse interrupts with tasks. I suspect this is
mostly because most preemptive systems use the interrupts
to switch task( not very efficient in a RTOS ).
 Even in a non-preemptive, one can have some priority.
Management of the task queue can give similar effects.
Dwight