ULE: A Modern Scheduler for FreeBSD

The existing thread scheduler in FreeBSD was well suited towards the computing environment that it was developed in. As the priorities and hardware targets of the project have changed, new features and scheduling properties were required. This paper presents ULE, a scheduler that is designed with modern hardware and requirements in mind. Prior to discussing ULE, the designs of several other schedulers are presented to provide some context for comparison. A simple scheduler profiling tool is also discussed, the results of which provide a basis for making simple comparisons between important aspects of several schedulers. 1 Motivation The FreeBSD project began a considerable shift in kernel architecture for the 5.0 release. The new architecture is geared towards SMP (Symmetric MultiProcessing) scalability along with low interrupt latency and a real-time-like preemptable kernel. This new architecture presents opportunities and challenges for intelligent management of processor resources ...

• Type: Conference
• Year: 2003
• Where: BSDCON
• Authors: Jeff Roberson
• Keywords: BSDCON 2003, Core Scheduling Algorithms, Operating System, Scheduler Profiling Tool, Thread Scheduler