Linux performance tweaks (TCP/UDP, swap, VFS)

99-sysctl.conf

# https://docs.continuent.com/tungsten-clustering-5.0/performance-networking.html
# https://wiki.archlinux.org/index.php/Sysctl
# https://pubs.vmware.com/continuent/tungsten-replicator-3.0/performance-networking.html
# https://www.vultr.com/docs/how-to-setup-tcp-optimization-on-linux
# https://russ.garrett.co.uk/2009/01/01/linux-kernel-tuning/

fs.file-max = 2097152
net.core.netdev_max_backlog = 250000
net.core.somaxconn = 1024
net.core.rmem_max = 67108864
net.core.wmem_max = 67108864
net.ipv4.tcp_rmem = 4096 87380 67108864
net.ipv4.tcp_wmem = 4096 65536 67108864
net.ipv4.udp_rmem_min = 8192
net.ipv4.udp_wmem_min = 8192
net.ipv4.tcp_fastopen = 3
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 5000
net.ipv4.tcp_mtu_probing=1
net.ipv4.tcp_no_metrics_save = 1 
net.ipv4.tcp_slow_start_after_idle = 0
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_window_scaling = 1
vm.dirty_background_ratio = 20
vm.dirty_ratio = 40
vm.swappiness = 10
vm.vfs_cache_pressure = 70