RE: [PATCH rdma-core 0/5] Common systemd/udev based boot support

Steve Wise
2017-07-28T13:51:28Z

> > On Wed, Jul 26, 2017 at 09:05:03AM -0500, Steve Wise wrote:
> >
> > > > I think you should change this to create the RDMA device when the
> > > > module is installed and the hardware is present..
> > > >
> > >
> > > Not gonna happen. cxgb4 doesn't setup the queues, rss, irq mappings, etc,
until
> > > an interface is brought up. So iw_cxgb4 cannot initialize and register
with the
> > > rdma core until that happens.
> >
> > But it doesn't tear all that stuff down on ifdown?
>
> hmm. I need to relook at this. I'm very sure the intent was offload
connections do
> not get torn down if the link goes down.
>

Hey Jason,

Bringing down the NIC interfaces doesn't totally stop the adapter nor destroy
the queues needed for RDMA. It does bring the links down on the ethernet
interfaces though. So it behaves like I thought. I tested this by running an
rping, and while it was pushing rdma traffic, I did 'ifconfig ethX 0.0.0.0 down'
on the interface in use. The data flow stopped (and the iWARP/TCP stack started
retransmitting). I then brought the link back up, and after a few seconds the
rping traffic continued on.

Steve