Cambridge Mathematics Direct 6 Numbers and Number System Pupil's Book

The real-time patch adds CONFIG_PREEMPT_RCU, which improves latency by making certain RCU sections preemptable. 17.3.2. O(1) Scheduler The O(1) scheduler has been around since the days of Linux 2.5. It is mentioned here because it is a critical component of a real-time solution. The O(1) scheduler is a significant improvement over the previous Linux scheduler. It scales better for systems with many processes and helps produce lower overall latency. In case you are wondering, O(1) is a mathematical designation for a system of the first order. In this context, it means that the time it takes to make a scheduling decision is not dependent on the number of processes on a given runqueue. The old Linux scheduler did not have this characteristic, and its performance degraded with the number of processes.[121] 17.3.3. Creating a Real-Time Process You can designate a process as real time by setting a process attribute that the scheduler uses as part of its scheduling algorithm. Listing 17-4 shows the general method. Listing 17-4 ...»