Learn All About ‘SCHED_DEADLINE’ from Steven Rostedt at Open Source Summit 2017
The Open Source Summit North America touches down in the City of Angels this year, taking place September 11-14 at the JW Marriot LA Live in Los Angeles, Calif. Hosted by the Linux Foundation, Open Source Summit 2017 boasts the combined might of LinuxCon, ContainerCon, CloudOpen and Open Community Conference under one umbrella event. The summit will offer attendees the chance to collaborate, share insights and learn from the best and the brightest in the open source technology realm.
This year, VMware’s Steven Rostedt, an open source developer, will join 2,000 other technologists and open source community members at Open Source Summit 2017. Steven will deliver his talk entitled “Understanding SCHED_DEADLINE” on Monday, Sept. 11 at 11:50 a.m. Steven has spent most of his professional career dealing with real-time operating systems (RTOS) and worked to turn the Linux kernel into a RTOS.
Starting in Linux version 3.14, a new scheduling class called “SCHED_DEADLINE” was introduced. This scheduling class implements Earliest Deadline First (EDF) along with a Constant Bandwidth Scheduler (CBS) that is used to give applications a guaranteed amount of CPU for a periodic time frame.
This type of scheduling is extremely advantageous and has numerous use cases for robotics, media players and recorders, as well as virtual machine guest management. Steven’s talk will explain the history behind “SCHED_DEADLINE” and compare it with other various methods to deal with periodic deadlines. He will also discuss some of the issues with the current Linux implementation and some of the improvements that are currently in development.
Most Linux applications use the standard real-time priorities. Linux supplies 100 different priorities for real-time tasks over the normal task priorities that run as “SCHED_OTHER.” This means that the highest priority task that is ready to run will be scheduled, and won’t stop running until it voluntarily schedules out.
While priority-based scheduling is well-known, it doesn’t handle periodic scenarios properly. That’s where “SCHED_DEADLINE” comes into play. A system utilizing priority-based scheduling can only take advantage of at most 69 percent of a CPU. During his presentation, Steven will dive into the reasoning behind this and discuss how the “SCHED_DEADLINE” approach for periodic scheduling allows a periodic real-time designed system to fully utilize 100 percent of a CPU.
Understanding “SCHED_DEADLINE” holds crucial advantages for many using open source technologies. If you’re attending Open Source Summit 2017 in Los Angeles this year, be sure to catch Steven’s presentation for his expert insight on the matter. Also, as a gold sponsor of the summit, VMware will have its own booth where attendees can stop by and chat with open source developers and learn about some of our investments in open source. We hope to see you there!