Re: [PATCH 0/6] refactor RDMA live migration based on rsocket API

[Peter Xu <peterx@redhat.com>]

On Fri, Jun 07, 2024 at 08:49:01AM +0000, Gonglei (Arei) wrote:
> Actually we tried this solution, but it didn't work. Pls see patch 3/6
> 
> Known limitations: 
>   For a blocking rsocket fd, if we use io_create_watch to wait for
>   POLLIN or POLLOUT events, since the rsocket fd is blocking, we
>   cannot determine when it is not ready to read/write as we can with
>   non-blocking fds. Therefore, when an event occurs, it will occurs
>   always, potentially leave the qemu hanging. So we need be cautious
>   to avoid hanging when using io_create_watch .

I'm not sure I fully get that part, though.  In:

https://lore.kernel.org/all/ZldY21xVExtiMddB@x1n/

I was thinking of iochannel implements its own poll with the _POLL flag, so
in that case it'll call qio_channel_poll() which should call rpoll()
directly. So I didn't expect using qio_channel_create_watch().  I thought
the context was gmainloop won't work with rsocket fds in general, but maybe
I missed something.

Thanks,

-- 
Peter Xu