[openib-general] ibv_reg_mr limits?

[Roland Dreier]

    Arlin> Is there a memory registration limit with ibv_reg_mr?  My
    Arlin> pingpong test returns error when trying to register 100 MB
    Arlin> of memory on my server with 1GB of memory.

mthca (in the kernel) currently implements memory registration in a
fairly stupid way that requires it to allocate a contiguous chunk of
memory to hold the entire page table of the memory region being
registered.  This can be fixed but right now I would expect the limit
on a single registration to be ~64 MB (or less if memory is fragmented).

 - R.