linux sysctl.conf tuning

limits.conf

# /etc/security/limits.conf
*        soft    nofile    524288
*        hard    nofile    524288
root     soft    nofile    524288
root     hard    nofile    524288
*        soft    nproc     524288
*        hard    nproc     524288
root     soft    nproc     524288
root     hard    nproc     524288

su

# /etc/pam.d/su
session    required   pam_limits.so

sysctl.conf

# the minimum number of entries to keep in the ARP cache
net.ipv4.neigh.default.gc_thresh1=8096

# the soft maximum number of entries to keep in the ARP cache
net.ipv4.neigh.default.gc_thresh2=12288

# the hard maximum number of entries to keep in the ARP cache
net.ipv4.neigh.default.gc_thresh3=16384

# Have a larger connection range available
net.ipv4.ip_local_port_range=1024 65000

# Reuse closed sockets faster
net.ipv4.tcp_tw_reuse=1
net.ipv4.tcp_fin_timeout=15
net.ipv4.tcp_tw_recycle=0

# The maximum number of "backlogged sockets".  Default is 128.
net.core.somaxconn=40000
net.core.netdev_max_backlog=10000

# 16MB per socket - which sounds like a lot,
# but will virtually never consume that much.
net.core.rmem_max=16777216
net.core.wmem_max=16777216

# Various network tunables
net.ipv4.tcp_max_syn_backlog=20480
net.ipv4.tcp_max_tw_buckets=400000
net.ipv4.tcp_no_metrics_save=1
net.ipv4.tcp_rmem=4096 87380 16777216
net.ipv4.tcp_syn_retries=2
net.ipv4.tcp_synack_retries=2
net.ipv4.tcp_wmem=4096 65536 16777216
net.ipv4.tcp_mem=50576   64768   98152
#vm.min_free_kbytes=65536

# Connection tracking to prevent dropped connections (usually issue on LBs)
net.netfilter.nf_conntrack_max=3921300
net.ipv4.netfilter.ip_conntrack_generic_timeout=120
net.netfilter.nf_conntrack_tcp_timeout_established=86400
net.netfilter.nf_conntrack_tcp_timeout_time_wait=1

net.ipv4.ip_nonlocal_bind=1
net.ipv4.tcp_syncookies=1
net.ipv4.tcp_sack=1
net.ipv4.tcp_window_scaling=1
net.ipv4.tcp_keepalive_intvl=30
net.ipv4.tcp_moderate_rcvbuf=1
fs.file-max=520000

vm.swappiness=10