What is rcv_space in the 'ss --info' output, and why it's value is larger than net.core.rmem_max
Hi,
can anyone help me understand what is rcv_space in the 'ss --info output', e.g.:
# ss --info dst 1.1.1.1 State Recv-Q Send-Q Local Address:Port Peer Address:Port ESTAB 0 0 2.2.2.2:39464 1.1.1.1:ssh cubic wscale:7,0 rto:204 rtt:7.5/3 ato:40 cwnd:10 ssthresh:15 send 15.4Mbps rcv_rtt:4 rcv_space:517488
Second question is what units rcv_space is measured in. I noticed that that it value is always devidable by 8.
Third question is why is rcv_space larger than the limits net.core.rmem_max and net.ipv4.tcp_rmem
net.core.wmem_max = 131071 net.core.rmem_max = 13107 net.core.wmem_default = 229376 net.core.rmem_default = 229376 net.ipv4.tcp_mem = 7270 9693 14540 net.ipv4.tcp_wmem = 4096 16384 4194304 net.ipv4.tcp_rmem = 4096 8192 16384
Fourth question is how can one verify that the above sysctl parameters take effect. I thought ss would do it, but now I am not so sure.
Thanks!
References:
TCP(7)
/usr/share/doc/kernel-doc-2.6.32/Documentation/networking/ip-sysctl.txt
/usr/share/doc/kernel-doc-2.6.32/Documentation/sysctl/net.txt
/usr/include/netinet/tcp.h
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