[$] Addressing priority inversion with proxy execution

Priority inversion comes about when a low-priority task holds a resourcethat is needed by a higher-priority task, with the result that the wrongtask is the only one that can run. This problem is arguably most acute inrealtime settings, but it can happen in just about any system that hasmultiple tasks running. The variety ofscheduling classes provided by the Linux kernel make handling priorityinversion a difficult problem; the latest version of the proxyexecution patch series points toward a possible solution.