> This can be done efficiently as follows: > 1. kata-runtime listens on a vsock port > 2. kata-agent-port=PORT is added to the kernel command-line options > 3. kata-agent parses the port number and connects to the host > > This eliminates the reconnection attempts.
There will be an additional problem if do this: Who decides which port the `runtime` should listen? Consider the worst case: The ports selected by two `runtime` running in parallel always conflict, and this case is unavoidable, even if we can reduce the possibility of conflicts through algorithms. Because we don't have a daemon that can allocate unique port to `runtime`. > Userspace APIs to avoid the 2 second wait already exist: > > 1. The SO_VM_SOCKETS_CONNECT_TIMEOUT socket option controls the connect > timeout for this socket. Yes, it has the same effect > 2. Non-blocking connect allows the userspace process to do other things > while a connection attempt is being made. I don't think the `tunime` has anything to do except wait for the response from the `agent` at that moment Now let me sort out the currently known methods: 1. `runtime` does not connect until it receives the qmp event reported by qemu when the `agent` opens the vsock device. - The method looks inappropriate now. 2. adding a special case for vhost_vsock.ko. - Also inappropriate. 3. connect to `runtime` from `agent`. - `runtime` may not be able to choose the right port. 4. Use `SO_VM_SOCKETS_CONNECT_TIMEOUT` option. - The effect is similar to method 2, no need to modify the kernel module code. I have an additional question: If useing method 4, when `runtime` calls connect use NONBLOCK option with very short timeout in an infinite loop, the kernel maybe frequently creates timers. Is there any other side effects?
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