Modernizing the Meta Ads Service With an Open-Source Kernel Scheduler · Engineering at Meta
Science, Technology & Innovation · Jul 13, 2026
Meta used sched_ext (a BPF-based extensible scheduler) to prioritize ad-serving work, turning a Linux kernel upgrade latency issue into a 28% reduction in ads-retrieval p99 latency, a 1.1% increase in weighted ads ranked, and 3.28 MW of fleet power savings—showing scheduler choice can affect business KPIs.
Modernizing the Meta Ads Service With an Open-Source Kernel Scheduler · Engineering at Meta
Science, Technology & Innovation · Jul 13, 2026
Meta implemented CPU soft-partitioning by request criticality (via sched_ext callbacks) to split CPUs into two dynamic pools for latency‑critical vs. less‑sensitive threads, improving L3 locality and reducing DRAM accesses—and achieving a 28% p99 latency drop on ads retrieval, a 1.1% weighted-ads-ranked gain, 1.6% lower CPU utilization, and supporting a 3.28 MW power‑saving estimate—showing scheduler-level separation of critical-path threads can unlock gains beyond application-level prioritization.
Modernizing the Meta Ads Service With an Open-Source Kernel Scheduler · Engineering at Meta
Science, Technology & Innovation · Jul 13, 2026
Meta says upstreaming sched_ext into Linux v6.12 as a BPF-based scheduler extension lets operators run workload-specific scheduling on standard kernels (no private forks), making features like cache-aware placement, ROI-based routing, and NUMA steering practical and positioning scheduler policy as a competitive software layer across hyperscalers, cloud providers, and embedded teams.
Modernizing the Meta Ads Service With an Open-Source Kernel Scheduler · Engineering at Meta
Science, Technology & Innovation · Jul 13, 2026
Meta moved scheduler policy into a user-space BPF-loaded binary so it can deploy and iterate scheduling changes by restarting a process (not rebuilding the kernel), enabling faster experiments and subsequent user-space updates that cut service p99 latency and timeout errors without maintaining a kernel fork.