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- The goal is for the kernel to provide each application with a "virtual multiprocessor": the kernel controls the number of processors allocated to the application, but the application can use the processors wherever it wants.
- In Scheduler Activations, the kernel starts up what is effectively a new thread (a "scheduler activation") whenever it wants to notify the application of anything. Typically it does this by interrupting an existing activation, effectively delivering 2 notifications: one for the desired event and one for the preemption. Wouldn't it would be simpler and more efficient to do these notifications by leaving messages in shared memory, which the application can poll?
Miscellaneous Thoughts
- This new mechanism might also be useful in a VM world, where the hypervisor allocates cores to guest OSes (which adjust their requests based on demand), the guest OSes allocate course to applications (based on their requests), and applications schedule cores to fibers.
- The new OS APIs should be designed with polling in mind. For example, if an OS needs to reclaim a core from an application, it leaves a note in memory, which the application's nanoscheduler sees and then picks a thread to relinquish.