Differences

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--- os:linux:kernel-tuning [2021-04-24 20:47] – created Manuel Frei
+++ os:linux:kernel-tuning [2025-02-22 16:56] (current) – Manuel Frei
@@ Line 2: / Line 2: @@
-===== BBR Network Congestion Algorithm =====
+===== BBR Congestion Control Algorithm =====
 BBR is included since Linux 4.10. It won't show in net.ipv4.tcp_allowed_congestion_control or net.ipv4.tcp_available_congestion_control if the module tcp_bbr isn't loaded. This module is loaded automatically if activate bbr.
@@ Line 33: / Line 33: @@
 **Links**
-  *  [[https://github.com/google/bbr|Github: BBR]]
+  * [[https://github.com/google/bbr|Github: BBR]]
+  * [[https://cloud.google.com/blog/products/networking/tcp-bbr-congestion-control-comes-to-gcp-your-internet-just-got-faster|TCP BBR congestion control comes to GCP – your Internet just got faster]]
+===== FQ - Fair Queue traffic policing =====
+FQ (sometimes referred to as sch_fq because of the name of its kernel module name) is a packet scheduler which was implemented by Eric Dumazet like FQ_Codel and can be configured as queueing discipline (qdisc). FQ can be used as a drop in replacement for pfifo_fast.
+The CoDel wiki says this:
+>For servers with tcp-heavy workloads, particularly at 10GigE speeds, for queue management, we recomend sch_fq instead of fq_codel as of linux 3.12.
+-- [[https://www.bufferbloat.net/projects/codel/wiki/|CoDel Overview]]
+  * fq_codel - best for routers, hypervisors and best general purpose qdisc
+  * fq - best for fat servers with TCP only workload at 10Gbps
+Activate on the current system and replace qdisc on eth0 (not recommended).
+<code>
+sysctl -w net.core.default_qdisc=fq
+tc qdisc replace dev eth0 root fq
+</code>
+Persistent configuration. Reboot required to activate (recommended).
+<code>
+echo "net.core.default_qdisc = fq"  > /etc/sysctl.d/90-fq.conf
+</code>
+**Links**
+  * man 8 tc-fq
+  * [[https://github.com/torvalds/linux/blob/master/net/sched/sch_fq_codel.c|sch_fq_codel.c]]
+===== Ephemeral Ports =====
+<code>
+sysctl -w net.ipv4.ip_local_port_range="1024 65000"
+</code>
+Permanently set this configuration.
+<code>
+echo "net.ipv4.ip_local_port_range = 1024 65000" > /etc/sysctl.d/90-ephemeral_ports.conf
+</code>
+**Links**
+  * [[https://www.nginx.com/blog/tuning-nginx/|Tuning NGINX for Performance]]
+  * [[https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html|IP sysctl]]