Chapter 4 - DSpace at Waseda University
Chapter 4 - DSpace at Waseda University
Chapter 4 - DSpace at Waseda University
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<strong>Chapter</strong> 5<br />
mode [31]. In opposite, preemptive kernel controls to process th<strong>at</strong> can be stopped forcefully<br />
by using scheduling policy or other interrupt when process is working as kernel mode. FCFS<br />
(First-Come-First-Served) is the represent<strong>at</strong>ive non-preemptive scheduling and Round-Robin<br />
is the represent<strong>at</strong>ive preemptive scheduling.<br />
5.2.1 Preemptive Kernel<br />
The importance of embedded kernels [1], as same as all other OS is to have preemption. If<br />
the Linux kernel has a preemption function th<strong>at</strong> is the preemptive kernel. The preemptive<br />
kernel, the real-time characteristic, means there will be guarantee on deadline of high-priority<br />
task. As the response time of the real-time kernel in embedded systems is directly rel<strong>at</strong>ed to<br />
the safety and reliability of the systems, it is needed to minimize interval between response<br />
times by using the preemptive kernel.<br />
Figure 5.3 Process of interrupt of preemptive kernel<br />
Figure 5.3 shows the order of interrupts in the preemptive kernel. If the interrupt of a high<br />
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