MBUF Cluster Network freeze problem

[Joel Sherrill]

Antti P Miettinen wrote:
> 
> Have you tried playing with rtems_bsdnet_config.network_task_priority?
> 
> What is the rationale of not having time slicing for the networking
> tasks? I know they should not stay busy for long periods so time
> slicing should not be _needed_ but if there _are_ several tasks
> competing for CPU I think the reasonable thing to do would be to share
> the CPU between them. 

Timeslicing breaks the atomicity assumptions of the network stack.
The stack was designed to run in non-interruptable UNIX kernel space
so the tasks are non-preempt, non-timesliced.

Timeslicing implies that preemption is enabled.  Otherwise, your
timeslice expires and the kernel is not allowed to eject the task.

> Is there a performance penalty for time slicing?

Except for adding context switches at the end of time slices, it
is not measurable.  

> Or does the correct operation of the stack depend on network tasks not
> pre-empting each other?

Yes.

> --
> Antti P Miettinen
> Nokia Networks

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Joel Sherrill, Ph.D.             Director of Research & Development
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