Originally published on the HostingPodium Enterprise Engineering Blog .

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This guide details sysctl, BBR, and IRQ-affinity settings that let a Linux host sustain near line-rate on 100 GbE while keeping tail latency sub-50 µs.

Scope and audience

This guide assumes a Red Hat Enterprise Linux 9 (or AlmaLinux 9) host equipped with a Mellanox ConnectX-6 100 GbE NIC. The target audience is senior platform engineers responsible for latency-sensitive, high-throughput services such as distributed databases, AI model serving, or video transcoding pipelines.

Baseline kernel parameters

Before any tuning, capture the default sysctl set. The following command produces a reproducible baseline:

sysctl -a | grep -E "net \. core|net \. ipv4|net \.…