Kernel Scheduler Engineer, Core OS

Cupertino, California, United States Software and Services

The Darwin Scheduler team within Apple's Core OS organization is responsible for the delivery of a high-quality and performant kernel for every Apple product. Our software runs on your wrist in watchOS; in your pocket with iOS; on your desk in macOS; and on the high-performance systems driving the creative industry. The team focuses on key kernel technology areas such as CPU scheduling, power management, and threading models which are central to delivering industry-leading performance and battery life.

We are looking for a highly skilled Systems Engineer to join us in designing the next generation of Apple’s kernel scheduler. As one of the few vertically integrated systems shops remaining, our engineers have the unique opportunity to influence the entire stack—from silicon design to the behavior of the world's most advanced applications.

As a Kernel Engineer on the Scheduler team, you will drive the evolution of the XNU kernel to support the expanding capabilities of Apple Silicon. You will work on the heart of the operating system, designing scheduling policies that balance extreme performance with aggressive power efficiency. We are looking for a self-driven engineer who thrives on navigating complex system interactions. You will be responsible for identifying bottlenecks in highly parallel workflows, optimizing the interaction between hardware and software, and ensuring our OS scales gracefully from low-power embedded devices to massive high-performance workstation architectures.

• Scalability & Performance:
  Architect scheduler improvements to unlock the full potential of modern Apple Silicon. Identify and resolve lock contention, optimize synchronization primitives, and ensure linear scalability on large AMP systems.
• Virtualization Architecture:
  Drive improvements to kernel subsystems to support advanced virtualization workflows. Optimize the interaction between host and guest schedulers to minimize latency and overhead.
• Intelligent Workload Management:
  Design novel policies to manage system resources for diverse workloads, ensuring responsiveness for foreground applications while maximizing efficiency for background tasks.
• Cross-Platform Unification:
  Adapt and unify advanced scheduling concepts across our ecosystem, bringing sophisticated thread management features to all Apple platforms.
• Performance Analysis & Tooling:
  Develop bespoke benchmarking tools and qualification harnesses to validate scheduler behavior and drive data-driven architectural decisions.

• BS/MS/PhD in Computer Science, Computer Engineering, or equivalent experience.
• Technical Proficiency:
  Fluency in C and C++
• Problem Solving:
  Proven track record of debugging complex system issues (deadlocks, race conditions, performance regressions) and driving ambiguous problems to resolution.

• Systems Expertise: 2+ years of experience in Operating Systems development, with deep knowledge of kernel internals, and process/thread scheduling.
• Concurrency:
  Strong understanding of SMP/AMP architectures, synchronization primitives, lock-free algorithms, and cache coherency.

At Apple, base pay is one part of our total compensation package and is determined within a range. This provides the opportunity to progress as you grow and develop within a role. The base pay range for this role is between $150,400 and $277,600, and your base pay will depend on your skills, qualifications, experience, and location.

Apple employees also have the opportunity to become an Apple shareholder through participation in Apple’s discretionary employee stock programs. Apple employees are eligible for discretionary restricted stock unit awards, and can purchase Apple stock at a discount if voluntarily participating in Apple’s Employee Stock Purchase Plan. You’ll also receive benefits including:
Comprehensive medical and dental coverage, retirement benefits, a range of discounted products and free services, and for formal education related to advancing your career at Apple, reimbursement for certain educational expenses — including tuition.

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