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REAL TIME PROGRAMMING, Part IV

Problems with RT programming under Linux

Security

• SCHED_FIFO and mlockall() require either root permission or CAP_RESOURCE.
• easier to solve if "standard" kernels came with capabilities enabled.
• otherwise, "helper" apps are needed for root access
• security implications
  • yeah?

Kernel issues

• despite many improvements, the kernel is still not good enough.
• interrupts are still blocked for significant fractions of "lowest-latency" processing times
• conditional_schedule() not called in all the right places.
• SCHED_FIFO tasks not always run deterministically
• 2.5/2.6 might be better.
• more testing needed.