Re: [PATCH rdma-next 0/3] Support out of order data placement

Jason Gunthorpe
2017-06-12T17:14:36Z

On Mon, Jun 12, 2017 at 05:11:09PM +0000, Parav Pandit wrote:

> > This is why inverting the flag in the kernel makes much more sense.
> When you say invert the flag, which flag do you mean?
> Capability flag or QP attribute?

QP attribute.

> Let's not mix PCIe write ordering with RDMA level out-of-order
> processing. IB spec clearly says, as I reiterated in the
> Documentation/out_of_order.txt - that application should not depend
> on the write data until write_with_imm arrives or subsequent rdma
> send arrives at responder side. If some MPI or other application
> have taken shortcut based on some platform, they have to help
> themselves. This path is not intent to address such issue.

Exactly - all spec conformant ULPs are compatible with enabling this
new function of mlx5.

There is no reason to add a flag at all, except to retain
compatibility with certain non-confomant ULPs. We have none of those
in the kernel, so kernel QPs should always have the flag on.

Jason