Published at LXer:
The Linux scheduler, in both the mainline and realtime versions, provides a couple of scheduling classes for realtime tasks. These classes implement the classic POSIX priority-based semantics, wherein the highest-priority runnable task is guaranteed to have access to the CPU. While this scheduler works as advertised, priority-based scheduling has a number of problems and has not been the focus of realtime research for some time. Cool schedulers in this century are based on deadlines instead. Linux does not yet have a deadline scheduler, though there is one in the works. A recent discussion on implementing the full deadline model has shown, once again, just how complex it can be to get deadline scheduling right in the real world.
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