Chapter 13. System calls in RHEL for Real Time

The sched_yield() function is designed for a processor to select a process other than the running one. This type of request is prone to failure when issued from within a poorly-written application.

When the sched_yield() function is used within processes with real-time priorities, it can display unexpected behavior. The process that calls sched_yield() moves to the tail of the queue of processes running at same priority. When there are no other processes running at the same priority, the process that called sched_yield() continues to run. If the priority of that process is high, it can potentially create a busy loop, rendering the machine unusable.

In general, do not use sched_yield() on real-time processes.

The getrusage() function retrieves important information from a specified process or its threads, including the number of context switches, page faults, and memory usage.

The function reports on information such as:

getrusage() enables you to query an application to provide information relevant to both performance tuning and debugging activities. getrusage() retrieves information that would otherwise need to be cataloged from several different files in the /proc/ directory and would be hard to synchronize with specific actions or events on the application.