# Meta Boosts Ad Service Performance With Open-Source Kernel Scheduler Custom scheduling policy delivers 28% latency reduction and 3.28MW power savings. - **Source:** [Facebook Engineering](https://engineering.fb.com) - **Published:** 2026-07-13 - **Topic:** [Software & Engineering](https://brifing.si/c/engineering) - **Original article:** - **On Brifing:** https://brifing.si/s/b0ab00c7-f0ad-4f7b-8eed-fe8366a26810 ## The Criticality of Ad Latency Meta's ad platform handles over 5 million requests per second. Millisecond-level latency improvements enhance ad relevance and strengthen advertiser ROI. The performance regression in Linux 6.9 kernel upgrade posed a major challenge for this high-throughput system. ## Limitations of CFS and EEVDF Traditional Linux schedulers (CFS/EEVDF) provided generic solutions unaware of workload context. In Meta's ad workflow, certain threads are more critical than others, but standard schedulers couldn't make this distinction. ## Enter sched_ext This BPF-based open-source framework was developed in collaboration with Google's ghOSt team. By running custom policies in user space, it enables ad workload-specific optimizations without waiting for kernel updates. ## CPU Pool Optimization The scheduler partitions CPUs into two flexible pools for latency-sensitive and background work. These dynamically adjusted pools improve L3 cache locality and reduce costly DRAM access. ## Rapid Iteration in User Space Policies packaged as BPF programs can be updated without kernel recompilation. This enabled additional 60% latency improvements through optimizations delivered in days rather than months. ## Tangible Results sched_ext deployment achieved 28% tail latency reduction in ad retrieval, 3.28MW power savings, and 1.1% more ads ranked. Timeout errors decreased by 18%, demonstrating significant QoS improvements. ## Strategic Transformation Initially a kernel upgrade workaround, sched_ext has become Meta's continuous optimization platform. Ad services now maintain peak performance independently of future Linux scheduler changes. ## Sources covering this story - https://engineering.fb.com/2026/07/13/ml-applications/modernizing-the-meta-ads-service-with-an-open-source-kernel-scheduler/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._