Welcome to LWN.net, where thousands of subscribers rely on the best news from the Linux and free software communities. Jonathan Corbet explores the concept of “lazy preemption” in the kernel’s CPU scheduler, offering a balance between system throughput and response time. Lazy preemption aims to simplify scheduling while providing better results. With patches from Peter Zijlstra, the kernel’s scheduler adds a new flag, TIF_NEED_RESCHED_LAZY, to defer preemption until necessary. The goal is to transition to a scheduler with only two non-realtime modes: PREEMPT_LAZY and PREEMPT_FULL, ultimately eliminating the need for voluntary preemption points. This work aims to create a more efficient and streamlined kernel scheduling system.
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