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@gheffern gheffern commented Nov 8, 2025

Apply specific kernel network tuning parameters to the OpenShift profile (/profiles/openshift/tuned.conf) to support high bandwidth-delay product links.

The following TCP settings are added:
net.ipv4.tcp_notsent_lowat=131072: Sets tcp_notsent_lowat to a value intended to balance throughput and latency while limiting total socket memory usage.
net.ipv4.tcp_slow_start_after_idle=0: Disables slow start after a connection has been idle, allowing immediate maximum throughput upon resuming data transfer.
net.ipv4.tcp_rmem="4096 131072 16777216": Increases the maximum TCP receive buffer size to improve performance on high-bandwidth-delay product connections.
net.ipv4.tcp_wmem="4096 16384 16777216": Increases the maximum TCP send buffer size for similar reasons.

These changes are based on work done by Cloudflare for improving TCP performance on high bandwidth-delay product links but are more conservative in adjusting rmem and wmem

Reference: https://blog.cloudflare.com/optimizing-tcp-for-high-throughput-and-low-latency/

…tency

Apply specific kernel network tuning parameters to the OpenShift profile
(/profiles/openshift/tuned.conf) to support high bandwidth-delay product links.

The following TCP settings are added:
net.ipv4.tcp_notsent_lowat=131072: Sets tcp_notsent_lowat to a value intended to balance throughput and latency while limiting total socket memory usage.
net.ipv4.tcp_slow_start_after_idle=0: Disables slow start after a connection has been idle, allowing immediate maximum throughput upon resuming data transfer.
net.ipv4.tcp_rmem="4096 131072 16777216": Increases the maximum TCP receive buffer size to improve performance on high-bandwidth-delay product connections.
net.ipv4.tcp_wmem="4096 16384 16777216": Increases the maximum TCP send buffer size for similar reasons.

These changes are based on work done by Cloudflare for improving TCP
performance on high bandwidth-delay product links but are more conservative in adjusting rmem and wmem

Reference: https://blog.cloudflare.com/optimizing-tcp-for-high-throughput-and-low-latency/

Signed-off-by: Graham Heffern <[email protected]>
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