Re: [PATCH 1/2] migration/rdma: Increase the backlog from 5 to 128

[Pankaj Gupta]

> > > >  migration/rdma.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/migration/rdma.c b/migration/rdma.c
> > > > index c7c7a384875b..2e223170d06d 100644
> > > > --- a/migration/rdma.c
> > > > +++ b/migration/rdma.c
> > > > @@ -4238,7 +4238,7 @@ void rdma_start_incoming_migration(const char 
> > > > *host_port, Error **errp)
> > > >
> > > >      trace_rdma_start_incoming_migration_after_dest_init();
> > > >
> > > > -    ret = rdma_listen(rdma->listen_id, 5);
> > > > +    ret = rdma_listen(rdma->listen_id, 128);
> > >
> > > 128 backlog seems too much to me. Any reason for choosing this number.
> > > Any rationale to choose this number?
> > >
> > 128 is the default value of SOMAXCONN, I can use that if it is preferred.
>
> AFAICS backlog is only applicable with RDMA iWARP CM mode. Maybe we
> can increase it to 128.these many

Or maybe we first increase it to 20 or 32? or so to avoid memory
overhead if we are not
using these many connections at the same time.

> Maybe you can also share any testing data for multiple concurrent live
> migrations using RDMA, please.
>
> Thanks,
> Pankaj
>
> Thanks,
> Pankaj