为Redis 3.2.6调整Linux内核堆栈

Question

I am setting up a Redis 3.2.6 cluster. In this blog it is mentioned to change the following parameters for "Tuning the kernel network stack"

vm.swappiness=0                       # turn off swapping
net.ipv4.tcp_sack=1                   # enable selective acknowledgements
net.ipv4.tcp_timestamps=1             # needed for selective acknowledgements
net.ipv4.tcp_window_scaling=1         # scale the network window
net.ipv4.tcp_congestion_control=cubic # better congestion algorythm
net.ipv4.tcp_syncookies=1             # enable syn cookied
net.ipv4.tcp_tw_recycle=1             # recycle sockets quickly
net.ipv4.tcp_max_syn_backlog=NUMBER   # backlog setting
net.core.somaxconn=NUMBER             # up the number of connections per port
net.core.rmem_max=NUMBER              # up the receive buffer size
net.core.wmem_max=NUMBER              # up the buffer size for all connections

Can someone explain me how the above parameters effect the behavior of redis?

Also other than the ones mentioned above do I need to look into some other parameters for preparing the OS for redis installation?

Environment

• Debian 8
• RAM - 128 GB
• Cores - 24

Answer 1

Most of that flags seem related to optimize for very frequent TCP connections and for latency of TCP connections. In some cases they may help but Redis clients and servers already do the most important thing which is to disable the Nagle's algorithm. However the MOST critical things with setting up a Linux kernel for Redis are actually:

1. Disable THP (Transparent Huge Pages).
2. Allow memory overcommitting during fork().

If the above are not set correctly, recent versions of Redis will warn you.