Re: [Qemu-stable] [Qemu-devel] [PATCH] rdma: fix multiple VMs parallel migration

[Michael R. Hines]

No top-posting, please.

On 09/03/2013 12:20 AM, Frank Yang wrote:
> Yes, it depends on low-level implementation. During my earlier test,
> using one CQ to send and receive may cause packet loss with heavy load:
> the destination thinks it send READY message successfully but the source
> still waits for it. This situation always happens when the destination 
> polls
> receive CQE first.
>
> So I think using only one CQ may cause packet conflict or something 
> like that,
> and it should be the driver bug. However, using two CQs fix the problem.

This doesn't seem like a very clear answer ..... are you sure its packet 
loss?

The queue pairs are supposed to be reliable - I've never experienced a 
situation
where packets were simply "dropped" for no reason without breaking the
connection and putting the QP into an error state.

- Michael