I'm working on a software which connects to a Real Time data server (using TCP) and I have some connections dropping. My guess is that the clients do not read the data coming from the server fast enough. Therefore I would like to monitor my TCP sockets. For this I found the "ss" tool.
This tool allows to see the state of every socket - here's an example line of the output of the command
ss -inm 'src *:50000'
ESTAB 0 0 126.96.36.199:50000 188.8.131.52:1105 mem:(r0,w0,f0,t0) sack rto:204 rtt:1.875/0.75 ato:40
My question is: what does the memory part mean?
Looking at the source code of the tool I found that the data is coming from a kernel structure (
sock.h). More precisely, it comes from the fields :
r = sk->sk_rmem_alloc w = sk->sk_wmem_queued; f = sk->sk_forward_alloc; t = sk->sk_wmem_alloc;
Does somebody know what they mean? My guesses are:
rmem_alloc: size of the inbound buffer
wmem_alloc: size of the outbound buffer
Here are my buffers sizes :
net.ipv4.tcp_rmem = 4096 87380 174760 net.ipv4.tcp_wmem = 4096 16384 131072 net.ipv4.tcp_mem = 786432 1048576 1572864 net.core.rmem_default = 110592 net.core.wmem_default = 110592 net.core.rmem_max = 1048576 net.core.wmem_max = 131071