[ofw] ndrping issues

Sean Hefty sean.hefty at intel.com
Tue Jan 5 12:21:08 PST 2010


Here are some more details on the ndrping issues that I mentioned during the
con-call this morning.  (Btw, the test fails with IBAL as well.)

The test fails if the client runs on mthca, and the server runs on mlx4.

The client code calls CreateEndpoint() using values of 0 for inbound and
outbound RDMA reads.  The 0's get mapped into the CM REQ messages.

The server calls CreateEndpoint() using the local HW max values.  These end up
getting pushed into the CM REP message.

Both the client and server QPs get configured using the value carried in the
REP.  I'm not sure where the best place is for a fix.

ndrping must at least be changed to pass in non-zero values (I think in place of
InboundReadLimit) on the client side.  It should probably be changed on the
server side to call GetConnectionData() to check the provided values and select
the minimum.

Also, there seems to be a bug in the mthca driver that allows the QP to be
configured with values that are too large, which results in the QP being unable
to send data.  Note that I'm running the test using RDMA writes, not reads, and
the first send from the client is what never completes.

ndrping works if I hard code the limits to 1 on both sides of the connection.

- Sean




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