On Wed, Sep 04, 2019 at 03:19:21PM +0200, Juan Quintela wrote: > Eric Blake <ebl...@redhat.com> wrote: > > On 8/20/19 5:48 AM, Juan Quintela wrote: > >> Reviewed-by: Daniel P. Berrangé <berra...@redhat.com> > >> Signed-off-by: Juan Quintela <quint...@redhat.com> > >> --- > >> blockdev-nbd.c | 2 +- > >> chardev/char-socket.c | 2 +- > >> include/io/net-listener.h | 2 ++ > >> io/net-listener.c | 3 ++- > >> migration/socket.c | 2 +- > >> qemu-nbd.c | 2 +- > >> ui/vnc.c | 4 ++-- > >> 7 files changed, 10 insertions(+), 7 deletions(-) > > > > Just now noticing this one, even though the pull request is already sent... > > > >> > >> diff --git a/blockdev-nbd.c b/blockdev-nbd.c > >> index 7a71da447f..c621686131 100644 > >> --- a/blockdev-nbd.c > >> +++ b/blockdev-nbd.c > >> @@ -101,7 +101,7 @@ void nbd_server_start(SocketAddress *addr, const char > >> *tls_creds, > >> qio_net_listener_set_name(nbd_server->listener, > >> "nbd-listener"); > >> > >> - if (qio_net_listener_open_sync(nbd_server->listener, addr, errp) < 0) > >> { > >> + if (qio_net_listener_open_sync(nbd_server->listener, addr, 1, errp) < > >> 0) { > >> goto error; > >> } > > > > Does this interfere with the ability to have more than one client > > connect to an NBD server during pull-mode incremental backup? Or can > > you still have multiple simultaneous clients, provided that the server > > has finished accepting the connection from the first before the second > > one starts? > > It is exactly the same than the old code. Old code always use one. We > need to have more than one for multifd. > > Once told that, if the connections don't start "very" simultaneosly > (i..e. With multifd we start <num channels> connections in paraller), > you will never notice that the backlog is one (sie of queue of pending > connections nowadays).
If incremental backup needs multiple concurrent connections, then you certainly *do* want to increase this value to something other than 1, or you will get random failures. As Juan says, this is a pre-existing problem with NBD though. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|