selftests/net: Add test for timing a bind request to a port with a populated bhash entry

2022-08-25T02:30:09Z

This test populates the bhash table for a given port with MAX_THREADS * MAX_CONNECTIONS sockets, and then times how long a bind request on the port takes. When populating the bhash table, we create the sockets and then bind the sockets to the same address and port (SO_REUSEADDR and SO_REUSEPORT are set). When timing how long a bind on the port takes, we bind on a different address without SO_REUSEPORT set. We do not set SO_REUSEPORT because we are interested in the case where the bind request does not go through the tb->fastreuseport path, which is fragile (eg tb->fastreuseport path does not work if binding with a different uid). To run the script: Usage: ./bind_bhash.sh [-6 | -4] [-p port] [-a address] 6: use ipv6 4: use ipv4 port: Port number address: ip address Without any arguments, ./bind_bhash.sh defaults to ipv6 using ip address "2001:0db8:0:f101::1" on port 443. On my local machine, I see: ipv4: before - 0.002317 seconds with bhash2 - 0.000020 seconds ipv6: before - 0.002431 seconds with bhash2 - 0.000021 seconds Signed-off-by: Joanne Koong Signed-off-by: Jakub Kicinski

kernel/tools/testing/selftests/net/bind_bhash.c, branch linux-6.2.y

selftests/net: Add test for timing a bind request to a port with a populated bhash entry