Verify the preempt-thread-only and coop-thread-only configurations

[zephyrbot]

Reported by Benjamin Walsh:

Mostly an audit and testing exercise. We expect a user to be able to configure the system with only preempt threads (tasks) or only coop threads (fibers). In the second case, the scheduler, especially the interrupt exit code should never have to even check if it has to do a context switch.

[Ben: there's probably a bit more work than just testing involved here, like completely disabling the preemptive scheduler when there are only coop threads]

(Imported from Jira ZEP-929)

[zephyrbot]

by Mark Linkmeyer:

Per email from Ben Walsh on 10/18/16, this story is on track for 1.6.

[zephyrbot]

by Mark Linkmeyer:

Per conversation with Ben, this story is being converted to a task because it's really a testing task. If the testing reveals bugs, then bug entries will be created in Jira. If the testing reveals optimization is needed, then new optimization stories will be created. This testing work (of GH-2436) is not critical to the 1.6 release and it will not be completed in time for the 1.6 release either, so GH-2436 is being moved to 1.7 too.

[zephyrbot]

by Mark Linkmeyer:

There seems to be some problem with Jira. It doesn't allow changing the issue type to Task for some reason. I've submitted a ticket to the LF for help. In the meantime I'm assigning this to myself so I don't forget to complete the issue type change. Once it's done, I'll assign it back to Ben.

[zephyrbot]

by Mark Linkmeyer:

Assigning back to Ben since Andy was able to get it converted to a task.

[zephyrbot]

by Benjamin Walsh:

Anas Nashif Andy Ross Andrew Boie Mark Linkmeyer I don't know how much more work we want to put into this feature. I'm able to run the philosophers demo with the patches now in gerrit, which means that both coop-only and preempt-only are at least sane from the kernel's point of view. However, some subsystems might rely on having both coop and preempt scheduling enabled, so I'm not sure how much coverage we can get. This is a very advanced feature anyway, where an application would probably provide every parts and tweak very closely what priorities all threads in the system would run at, especially if using coop-only mode.

[zephyrbot]

by Benjamin Walsh:

Commit 2f28041 is the last in series of patches that fixes issues running the philosophers demo in coop-only and preempt-only modes.

[zephyrbot]

by Mark Linkmeyer:

Correcting the priority field