Performance Engineer, Kernel and Memory

Available Locations

• Austin, US
• New York, NY
• Washington DC

About the Role

At Cloudflare, we have our eyes set on an ambitious goal: to help build a better Internet. Today the company runs one of the world’s largest networks that powers approximately 25 million Internet properties, for customers ranging from individual bloggers to SMBs to Fortune 500 companies. Cloudflare protects and accelerates any Internet application online without adding hardware, installing software, or changing a line of code. Internet properties powered by Cloudflare all have web traffic routed through its intelligent global network, which gets smarter with every request. As a result, they see significant improvement in performance and a decrease in spam and other attacks. Cloudflare was named to Entrepreneur Magazine’s Top Company Cultures list and ranked among the World’s Most Innovative Companies by Fast Company.

We realize people do not fit into neat boxes. We are looking for curious and empathetic individuals who are committed to developing themselves and learning new skills, and we are ready to help you do that. We cannot complete our mission without building a diverse and inclusive team. We hire the best people based on an evaluation of their potential and support them throughout their time at Cloudflare. Come join us!

About the Department

Cloudflare’s engineering teams build and maintain the systems and products that power our global platform. A global platform which is within approximately 50 milliseconds of about 95% of the Internet connected population, serving on average, over 46 million HTTP requests per second.

About the Team

Delivering this platform with high performance and efficiency depends on advanced Linux kernel and hardware capabilities, and that is where this team works.

The Performance Team owns overall system and application performance across that fleet: resource optimization, instrumentation, and the tooling that lets us see what the hardware is actually doing. System memory sits alongside CPU cycles, network processing, and storage IOPS as a first-class resource, and how the kernel manages it is increasingly the thing that decides how hot we can safely run every machine we own.

We work upstream first. Several of us maintain or regularly contribute to the Linux kernel, and our default is to fix problems in mainline rather than carry private patches. This role is built on that principle.

The problem you would own

Using memory efficiently is one of the highest-leverage problems we have. At our scale, how the kernel's memory-management subsystem behaves under pressure has direct consequences for both performance and cost. As DRAM prices climb, getting more out of the memory we already own is a real lever on infrastructure spend.

Using custom low-overhead instrumentation on production servers, we have identified several scalability bottlenecks in the kernel memory layer that show up under real workloads. We are looking for an expert to take on these problems, fix them against production workloads, and drive the changes upstream. Solving them lifts efficiency and latency across the entire fleet rather than in one place.

What you will do

• Diagnose and fix performance and scalability bottlenecks in the Linux kernel memory-management subsystem, informed by real production telemetry at a scale few environments can offer.
• Land your work upstream. We expect MM changes to go to mainline first and want you to keep doing the maintainership and review work that earns standing in the community.
• Build and extend low-overhead kernel instrumentation (tracepoints, BPF, perf) so we keep measuring before we change, and prove the impact afterwards.
• Partner with kernel, networking, storage, and product engineers across the company to turn observed system behavior into concrete MM improvements.
• Set technical direction for how Cloudflare uses, tunes, and evolves kernel memory management as we push utilization higher.

Requirements

• Deep expertise in the Linux kernel memory-management subsystem: the page allocator, virtual memory and memory mapping, reclaim, and the locking and concurrency that hold it together.
• A track record of upstream Linux contribution, ideally including maintainership or sustained work in MM or an adjacent subsystem.
• Strong systems programming in C, with the judgement to make high-risk changes to shared infrastructure safely.
• Ability to dive deep into a complex codebase while keeping the fleet-wide picture in mind, and to own a problem and its outcome rather than a single patch.
• Clear communication with engineers across many teams, since the symptoms of an MM problem usually show up far from the MM code.

Bonuses

• Strong understanding of Linux kernel internals pertaining to memory management
• Experience troubleshooting and resolving performance issues in large-scale distributed systems.
• Experience with large scale configuration/deployment management.