Staff Software Engineer - Linux Kernel

About the Role

Fastly's Kernel and Host Networking team builds and ships the Linux kernel that runs on every server in our global edge network, and every customer request passes through it. As a Staff engineer you own technical problems end to end: from a crash signature or a new NIC on the bench, through root cause and design, to a change that is upstreamed and safely running on thousands of servers.

The work spans networking, XDP and eBPF, memory, performance and hardware enablement. Formal CS education is not required; demonstrable experience is what matters.

What You'll Do

• Set technical direction for kernel projects, own them end to end from problem statement to fleet rollout, and mentor engineers on the team
• Take new servers, CPUs and NICs from first boot to full fleet: drivers, IRQ affinity, RSS and queue layout on high core count hosts
• Improve datapath and transport performance with XDP, eBPF and protocol work based on IETF specifications
• Debug problems that cross layers with application teams, such as MTU behavior, cgroup memory accounting and packet filtering
• Develop and maintain kernel changes and Fastly kernel modules on our long term kernel line, and reduce our private delta by upstreaming
• Make sure state pushed from control planes to eBPF and XDP programs is applied, verified and safe to roll back
• Own kernel health in production: triage crashes, WARNs and regressions across the fleet, find the root cause and ship the fix
• Own and improve the kernel release process and the signals behind it: CI, bake, canary, staged rollout and rollback across thousands of servers, plus crash metrics and drift detection
• Join the on-call rotation, lead the kernel side of incidents and drive follow-up actions to closure

What We're Looking For

• 7+ years of related engineering experience, including substantial production C, with 3 of those years leading technical projects
• Production Linux kernel development, including debugging use-after-free, refcount and leak bugs with KASAN, kdump, ftrace, perf or bpftrace
• Working knowledge of the scheduler and memory management (EEVDF, memcg)
• Experience managing a kernel patch stack and working with upstream communities
• Solid understanding of the Linux network stack (TCP/IP, sk_buff lifecycle, qdiscs, NIC drivers) and XDP or eBPF, with deep expertise in at least one of these areas
• Operational discipline: staged rollouts, canaries, kill switches, observability, postmortems and closing action items
• Understanding of distributed systems: control plane and datapath consistency, partial failure and safe config rollout at fleet scale
• Ability to design broadly scoped work and drive it across teams

Preferred Qualifications

• Upstream kernel contributions or subsystem maintainership
• Deep knowledge of transport protocols from IETF RFCs: QUIC, TCP, ECN and L4S, MASQUE
• Hardware enablement on AMD EPYC or Intel platforms, and NIC drivers such as mlx5, ice or i40e
• Load balancing or traffic steering systems
• CDN or large edge network environments
• Container networking: network namespaces, veth, cgroups, and eBPF-based CNI datapaths

Interview Policy

To ensure a fair and equitable interview process for everyone, the use of AI technologies—including real-time transcription tools, automated scripts, AI copilots, or external assistants—is strictly prohibited during the interview process unless explicitly authorized by the company in advance.