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Effects of Disabling Interrupts or Pre-Emption on Response Latency
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Rate Monotonic Scheduling
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**Assumption**

  No resource sharing (processes do not share resources, e.g. a hardware
  resource, a queue, or any kind of semaphore blocking or non-blocking
  (busy-waits)).

  Wikipedia “Rate Monotonic Scheduling”

**Real world**

We must protect shared resources with locks of some kind. The most aggressive:

#. Disabling interrupts, and
#. Disabling pre-emption.

What are the effects of real-time performance when this assumptions is violated?

Normal Interrupt Processing
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.. figure:: normal_interrupt.png
   :align: center

Effect of Disabling Interrupts
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.. figure:: disabling_interrupts.png
   :align: center

Effect of Disabling Pre-emption
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.. figure:: disabling_preemption.png
   :align: center