Chris Down
Production Engineer, Reliability Foundation
London, England, United Kingdom
Summary
🤩
RockstarChris Down is a production engineer and reliability specialist with 14 years of experience building and debugging infrastructure at Meta, where his Linux kernel and systemd work runs on billions of devices. He focuses on memory management, cgroups, and system responsiveness—authoring innovations like printk indexing and driving fleet-wide CPU and memory improvements. Trusted to lead incident response and design long-term fixes, he bridges hardware and software (TLB/MMU to userspace) and consults on services handling hundreds of petabytes. A habitual open-source maintainer, he contributes to systemd, osquery, and oomd, improving observability and OOM handling across the industry. He mentors senior engineers and shapes reliability culture, able to ramp quickly in C, Rust, or Python while solving cross-team distributed-system problems. Less obvious: he combines deep kernel internals with production playbooks, redesigning on-call models and kernel console behavior to reduce toil and improve real-world responsiveness.
14 years of coding experience
14 years of employment as a software developer
English, Chinese
Stackoverflow
1,700reputation
144kreached
10answers
3questions
apache-kafka
top-5%
Github Skills (33)
network-configuration10
filesystem10
c-language10
system-programming10
python10
init10
linux10
c1110
file-operations10
c1710
system10
performance-optimization10
fileio10
systemd10
cprogramming-language10
Programming languages (19)
Github contributions (5)
systemd/systemd
Nov 2017 - Sep 2021
The systemd System and Service Manager
Role in this project:
Back-end Developer & Systems Engineer
Back-end Developer & Systems EngineerContributions:19 reviews, 76 PRs, 38 pushes in 3 years 10 months
Contributions summary:Chris's contributions primarily focus on enhancing the systemd codebase, with significant changes related to DHCP, network configuration, and cgroup management. They addressed bugs, such as double-free issues in networkd and improved logging in DHCP. Moreover, they made important improvements to cgroup handling, specifically related to memory limits and configurations, ensuring correct behavior in various scenarios. They also added features for systemd-analyze and expanded on virtualization detection.
servicesservice-managervagrantlinuxinit
osquery/osquery
Nov 2014 - Nov 2015
SQL powered operating system instrumentation, monitoring, and analytics.
Role in this project:Back-end & DevOps Engineer
Back-end & DevOps EngineerContributions:7 commits, 4 PRs, 1 push in 1 year
Contributions summary:Chris's contributions primarily focused on improving the codebase's quality and maintainability within the osquery project. They added a missing LLVM license and implemented PEP8 and lint conformance to in-house scripts, addressing stylistic issues and disabling problematic linters. Additionally, they modified the processes and users tables to correct for errors. They also made improvements to the profiling and benchmarking tools.
instrumentationanalyticsoperating-systemsecuritysql
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