itsy bitsy Unix

Dwight K. Elvey dwight.elvey at
Fri Mar 18 11:31:32 CST 2005

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

 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.

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