How much memory is consumed by the Linux kernel per TCP/IP network connection?

For a TCP connection memory consumed depends on

1) size of sk_buff (internal networking structure used by linux kernel)

2) the read and write buffer for a connection

the size of buffers can be tweaked as required

root@x:~# sysctl -A | grep net | grep mem

check for these variables

these specify the maximum default memory buffer usage for all network connections in kernel

net.core.wmem_max = 131071

net.core.rmem_max = 131071

net.core.wmem_default = 126976

net.core.rmem_default = 126976

these specify buffer memory usage specific to tcp connections

net.ipv4.tcp_mem = 378528 504704 757056

net.ipv4.tcp_wmem = 4096 16384 4194304

net.ipv4.tcp_rmem = 4096 87380 4194304

the three values specified are " min default max" buffer sizes. So to start with linux will use the default values of read and write buffer for each connection. As the number of connection increases , these buffers will be reduced [at most till the specified min value] Same is the case for max buffer value.

These values can be set using this sysctl -w KEY=KEY VALUE

eg. The below command ensures the read and write buffers for each connection are 4096 each.

sysctl -w net.ipv4.tcp_rmem='4096 4096 4096'

sysctl -w net.ipv4.tcp_wmem='4096 4096 4096'

原文

http://stackoverflow.com/questions/8646190/how-much-memory-is-consumed-by-the-linux-kernel-per-tcp-ip-network-connection