[$] Migration disable for the mainline
The realtime developers have been working for many years to
create a kernel where the highest-priority task is always able to run
without delay. That has meant a long process of finding and fixing
situations where high-priority tasks might be blocked from running; one of
the persistent problems in this regard has been kernel code that disables
preemption. One tool that the realtime developers have reached for is
disabling migration (moving a process from one CPU to another) rather than
preemption; this approach has not been entirely popular among scheduler
developers, though. Even so, the solution would appear to be this
migration-disable patch set from scheduler developer Peter Zijlstra.