K8S 性能優化 - OS sysctl 調優

前言

K8S 性能優化系列文章，本文為第一篇：OS sysctl 性能優化參數最佳實踐。

參數一覽

sysctl 調優參數一覽

# Kubernetes Settings
vm.max_map_count = 262144
kernel.softlockup_panic = 1
kernel.softlockup_all_cpu_backtrace = 1
net.ipv4.ip_local_reserved_ports = 30000-32767

# Increase the number of connections
net.core.somaxconn = 32768

# Maximum Socket Receive Buffer
net.core.rmem_max = 16777216

# Maximum Socket Send Buffer
net.core.wmem_max = 16777216

# Increase the maximum total buffer-space allocatable
net.ipv4.tcp_wmem = 4096 87380 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216

# Increase the number of outstanding syn requests allowed
net.ipv4.tcp_max_syn_backlog = 8096


# For persistent HTTP connections
net.ipv4.tcp_slow_start_after_idle = 0

# Allow to reuse TIME_WAIT sockets for new connections
# when it is safe from protocol viewpoint
net.ipv4.tcp_tw_reuse = 1

# Max number of packets that can be queued on interface input
# If kernel is receiving packets faster than can be processed
# this queue increases
net.core.netdev_max_backlog = 16384

# Increase size of file handles and inode cache
fs.file-max = 2097152

# Max number of inotify instances and watches for a user
# Since dockerd runs as a single user, the default instances value of 128 per user is too low
# e.g. uses of inotify: nginx ingress controller, kubectl logs -f
fs.inotify.max_user_instances = 8192
fs.inotify.max_user_watches = 524288

# Additional sysctl flags that kubelet expects
vm.overcommit_memory = 1
kernel.panic = 10
kernel.panic_on_oops = 1

# Prevent docker from changing iptables: https://github.com/kubernetes/kubernetes/issues/40182
net.ipv4.ip_forward=1

如果是 AWS，額外增加如下：

# AWS settings
# Issue #23395
net.ipv4.neigh.default.gc_thresh1=0

如果啟用了 IPv6，額外增加如下：

# Enable IPv6 forwarding for network plugins that don't do it themselves
net.ipv6.conf.all.forwarding=1

參數解釋

EOF

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