Senior Linux Kernel Driver Engineer

Fractile Ltd.; Greater London; Hybrid; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Equity ownership

Private medical, dental and vision

Contributory pension

25 days holiday plus bank holidays and

Life/Critical Illness Insurance

Job summary

Fractile Ltd. is seeking a Linux kernel driver engineer to design, develop, and maintain our AI accelerator’s kernel driver and its critical host-paths. You will own PCIe device management, DMA, and memory handling, and you’ll shape the userspace interface for robust, high-performance runtimes.

You’ll work with hardware, firmware, and ML teams in a fast-paced co-design environment, delivering measurable throughput gains while ensuring reliability and maintainability of kernel code.

Qualifications

• Experience shipping and maintaining Linux kernel drivers in production.
• Familiarity with PCIe-attached devices and custom hardware interfaces.

Responsibilities

• Design, develop, and maintain the Linux kernel driver for Fractile’s AI accelerator.
• Build the performance-critical kernel-space paths: PCIe, DMA, memory handling, interrupts, recovery.
• Define and evolve the userspace interface the runtime depends on for stability, debuggability, performance.
• Collaborate with hardware, firmware, runtime and ML engineers in a tight co-design loop.
• Improve tooling/workflows to move fast without breaking things.

Skills

Linux kernel driver

PCIe devices

C and/or Rust

Performance optimization

System-level debugging

Education

Computer Science, Electronic Engineering, Maths, Physics, or related degree

Job description

About Fractile

Fractile was founded in 2022 on the bet that, eventually, the world’s most capable AI systems would be limited in their impact by the time taken to produce useful outputs. We bet everything on the logical conclusion: that the only way to truly unlock this latent value, to make speed viable at scale, was to radically re-invent the hardware that we run our frontier AI models on. Ever since, we have been building chips and systems that tackle this problem: how to efficiently generate output at thousands of tokens per second, while handling the complexity and capacity challenges of operating large models at very long contexts.

The workloads that push to the limits of the current frontier are already transformational; it is the technical and economic limits on inference speed that are constraining progress. The defining work of the 21st century will be marked by the engine of inference delivering immense and diffuse chains of intellectual inquiry, in drug discovery, in software engineering, in materials discovery, in any field where progress is driven by deep reasoning and intelligence to resolve complex problems.

The Role

This role sits at the boundary between host and silicon. The kernel driver is key to keeping pace with our ultra-fast devices on cutting-edge server platforms. It’s a high-leverage layer where each win shows up as real throughput and latency gains.

You’ll be there for the pre-silicon simulations, first bring-up, first end-to-end runs, and the moments where performance jumps because of something you shipped.

What you’ll do

• Design, develop, and maintain the Linux kernel driver for Fractile’s AI accelerator

• Build the performance-critical kernel-space paths that keep the host stack moving: PCIe device management, DMA, memory handling, interrupt handling, and robust recovery paths

• Define and evolve the userspace interface the runtime depends on, with a focus on stability, debuggability, and performance

• Work in a tight co-design loop with hardware, firmware, runtime and ML engineers: validate assumptions, iterate on behaviour, and close gaps early

• Improve tooling/workflows so we move fast without breaking things

What we’re looking for

• You’ve shipped and maintained Linux kernel device drivers in production. Experience with PCIe-attached devices and custom hardware interfaces is ideal.

• Strong systems and performance instincts. You can reason about computer architecture, concurrency, and where the time goes

• Excellent C and/or Rust, and a pragmatic approach to building high-quality, maintainable & secure kernel code

• You enjoy hard kernel and system-level problems, and you take them end-to-end until the measurements move

• Computer Science, Electronic Engineering, Maths, Physics, or related degree and 3+ years of industry experience

Nice to have

• GPUs / ML accelerators / high-throughput I/O (NICs, RDMA, storage)

• Hardware bring-up or pre-silicon simulation experience

• Performance work: profiling, tracing, benchmarking, regression tracking

If you want to build the software where every driver win unlocks huge system performance, come build it together.

What We Offer

• Competitive salary: A competitive salary reflective of your experience and the specialist nature of the role.

• Equity & Ownership: meaningful equity so everyone shares in the value creation

• Benefits: Private Medical, Dental and Vision, Contributory Pension, 25 Days holiday plus bank holidays and Life/Critical Illness Insurance.

• Diverse & fun office: we believe the hardest problems get solved by the broadest range of minds. We are committed to Equal Employment Opportunity through attracting and retaining a diverse team and building an inclusive environment.

Fractile is seeking to increase the clock speed of global progress, one chip at a time. We’ve recently raised $220M from investors including Founders Fund and Accel and our most important work lies ahead. Join us!

Export controls

Our work involves technologies subject to UK, US and other international export control regulations. Certain roles may require additional eligibility checks to ensure compliance with applicable law. We'll be transparent about this throughout the hiring process.