[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re:[Qemu-devel] [PATCH v2] vhost-vsock: report QMP event whensetrunning
From: |
ning.bo9 |
Subject: |
Re:[Qemu-devel] [PATCH v2] vhost-vsock: report QMP event whensetrunning |
Date: |
Fri, 13 Dec 2019 15:11:54 +0800 (CST) |
> 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?
signature.asc
Description: Binary data