Preemptible large copies in kernel
(possible project)
Currently if a large copy between two processes is requested, the kernel may spend significant amount of time in the copying routine. This is not desirable as the latency of the system may increase too much and fullfilling any real-time guarantees is impossible. Of course, the userspace should avoid requesting such large copies and rather use shared memory, however, this would involve rewriting too much code in drivers and system servers. On the other hand, it is possible to make such large copies preemptible. For instance by unmasking interrupts after each 4kB chunk copied. If an interrupt occurs in this moment, the state of the copy must be saved and the scheduler gets a chance to run a different process. This makes soft real-time guarantees possible and reduces the latency of the system.