On Fri, 18 Apr 2014, Nicolas Carlier wrote: > > If the receiving QP does not have buffers available then the HCA will > > silently drop UD packets. This is somethig that tripped us up initialy. So > > its lossless only from HCA to HCA not QP to QP. > > > > Christoph, I'm very interesting by this. Do you have any documentation > related to this mechanisms? I'm troubleshooting an infiniband fabric where > I use heavily ipoib to collect multicast traffic. I see lot of gaps on the > application, but I can't map any of this gaps to drop counters or dropwatch > output.
There was a promise that MOFED 2.1 or 2.2 should support a counter for QP overrun but I have never seen that work. The counter is there but does not increment. > I'm sure drops don't occur upstream because I'm able to dump traffic before > the Infiniband Fabric without observing them. > I'm also able to dump traffic on another server inside the Infiniband Fabric > connected to the same leaf switch without observing them. Well looks like silent drops to me. One way to check is to verify the sequence ids in each multicast packet. We finally ended up with looking at all the counters in the fabric and if we could not account for it we assumed it was QP overrun. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
