On Wednesday, May 31, 2023 8:58 PM, Peter Xu wrote: > > > Hmm.. so we used to do socket_start_incoming_migration_internal() > > > before setting the right num for the preempt test, then I'm curious > > > why it wasn't failing before this patch when trying to connect with the > preempt channel.. > > > > > > Wei, do you know? > > > > I think there are two reasons: > > #1 "backlog" specifies the number of pending connections. As long as > > the server accepts the connections faster than the clients side > > connecting, connection will succeed. For the preempt test, it uses > > only 2 channels, so very likely to not have pending connections. (This > > is easier to trigger for the multifd case, e.g. use a much larger number > > like > 16). > > #2 per my tests (on kernel 6.2), the number of pending connections > > allowed is actually "backlog + 1", which is 2 in this case. Adding > > more pending connections will then be dropped. I'm not sure if " backlog + > 1" is true for older versions of kernel, though. > > Interesting to know, thanks. > > If there'll be a new version, please consider adding some of those into the > commit message.
OK, will resend with commit update. Plan to wait a bit in case there would be other feedbacks. > > Reviewed-by: Peter Xu <pet...@redhat.com> > > -- > Peter Xu