| ================================================================== |
| Effects of Disabling Interrupts or Pre-Emption on Response Latency |
| ================================================================== |
| |
| Rate Monotonic Scheduling |
| ========================= |
| |
| **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 |
| --------------------------- |
| |
| .. figure:: normal_interrupt.png |
| :align: center |
| |
| Effect of Disabling Interrupts |
| ------------------------------ |
| |
| .. figure:: disabling_interrupts.png |
| :align: center |
| |
| Effect of Disabling Pre-emption |
| ------------------------------- |
| |
| .. figure:: disabling_preemption.png |
| :align: center |
