Re: [PATCH] multifd: Set a higher "backlog" default value for listen()

[Juan Quintela]

Lei Wang <lei4.wang@intel.com> wrote:
> When destination VM is launched, the "backlog" parameter for listen() is set
> to 1 as default in socket_start_incoming_migration_internal(), which will
> lead to socket connection error (the queue of pending connections is full)
> when "multifd" and "multifd-channels" are set later on and a high number of
> channels are used. Set it to a hard-coded higher default value 512 to fix
> this issue.
>
> Reported-by: Wei Wang <wei.w.wang@intel.com>
> Signed-off-by: Lei Wang <lei4.wang@intel.com>

[cc'd daiel who is the maintainer of qio]

My understanding of that value is that 230 or something like that would
be more than enough.  The maxiimum number of multifd channels is 256.

Daniel, any opinion?

Later, Juan.

> ---
>  migration/socket.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/migration/socket.c b/migration/socket.c
> index 1b6f5baefb..b43a66ef7e 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -179,7 +179,7 @@ socket_start_incoming_migration_internal(SocketAddress 
> *saddr,
>      QIONetListener *listener = qio_net_listener_new();
>      MigrationIncomingState *mis = migration_incoming_get_current();
>      size_t i;
> -    int num = 1;
> +    int num = 512;
>  
>      qio_net_listener_set_name(listener, "migration-socket-listener");