This is a NIF which reimplements the gen_*:socket() systemcall as it was basically too slow when running with the namespece-support OTP added some release ago.
Basically, we preallocate a number of sockets in each and every namespace and will hand these ones out once someone needs them. This will speed things up considerably.
timer:tc(sysSock, sock, [100]). 329µs 100 sockets via a NIF malloc
Connect calls:
- 1000st => 445000 445ms 0.45µs/connection
- 100st => 50982 50ms 0.50µs/connection
Connect calls:
- 1000st => 460980 461ms 0.46µs/connection
- 100st => 52123 52ms 0.52µs/connection
Connect calls:
- 1000st => 254259 254ms 0.25µs/connection no nif alloc involved
- 100st => 31100 311ms 0.31µs/connection
Allocates 1000 fd's in nif + one gen_tcp:connect: 0.4ms
[pid 14582] 09:32:26.204530 open("/proc/self/ns/net", O_RDONLY) = 208
[pid 14582] 09:32:26.204870 open("/var/run/netns/topi", O_RDONLY) = 209
[pid 14582] 09:32:26.205192 setns(209, 1073741824) = 0
[pid 14582] 09:32:26.212117 close(209) = 0
[pid 14582] 09:32:26.212312 socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 209
[pid 14582] 09:32:26.212560 setns(208, 1073741824) = 0
[pid 14582] 09:32:26.235994 close(208) = 0
[pid 14582] 09:32:26.236152 fcntl(209, F_GETFL) = 0x2 (flags O_RDWR)
[pid 14582] 09:32:26.236262 fcntl(209, F_SETFL, O_RDWR|O_NONBLOCK) = 0
[pid 14582] 09:32:26.236396 bind(209, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("0.0.0.0")}, 16) = 0
[pid 14582] 09:32:26.236511 getsockname(209, {sa_family=AF_INET, sin_port=htons(40961), sin_addr=inet_addr("0.0.0.0")}, [16]) = 0
[pid 14582] 09:32:26.236609 connect(209, {sa_family=AF_INET, sin_port=htons(80), sin_addr=inet_addr("192.168.0.100")}, 16) = -1 EINPROGRESS (Operation now in progress)
09:37:10.133103 setns
09:37:10.155943 close 22ms
09:37:10.156119 setns
09:37:10.183946 close 27ms
09:38:46.797149 setns
09:38:46.804128 close 6ms
09:38:46.804604 setns
09:38:46.828103 close 24ms
setns takes: 7ms+23ms => 30-50ms
100st no netns : 22ms 0.22µs/connection
100st via netns : 3305ms 33ms/connection
100st via topins: 83ms 0.83µs/connection