On Wed, May 31, 2023 at 10:41:37AM +0000, Wang, Wei W wrote: > On Tuesday, May 30, 2023 10:41 PM, Peter Xu wrote: > > On Tue, May 30, 2023 at 05:02:59PM +0800, Wei Wang wrote: > > > The Postcopy preempt capability requires to be set before incoming > > > starts, so change the postcopy tests to start with deferred incoming > > > and call migrate-incoming after the cap has been set. > > > > > > Signed-off-by: Wei Wang <wei.w.w...@intel.com> > > > > 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. Reviewed-by: Peter Xu <pet...@redhat.com> -- Peter Xu
