[openib-general] basic IB doubt

[Ralph Campbell]

On Wed, 2006-08-23 at 12:28 -0500, Tang, Changqing wrote:
>  >
> >Actually, A knows the data is in B's memory when A gets the 
> >completion notice.  B can't rely on anything unless A uses the 
> >RDMA write with immediate which puts a completion event in B's CQ.
> 
> Ralph:
> 
> Can you give a few more words on 'immediate', I know A will have
> A completion event in its CQ, Does B receive a CQ event on the 
> Same RDMA operation as well ?
> 
> --CQ Tang

B doesn't get a completion event for a RDMA write initiated from A
unless A does something like the following:

     struct ib_send_wr wr;

     wr.opcode = IB_WR_RDMA_WRITE_WITH_IMM;
     wr.imm_data = cpu_to_be32(value);
     ...
     ib_post_send(qp, &wr, NULL);

B will get a completion event with the IB_WC_WITH_IMM
flag set in struct ib_wc.wc_flags and ib_wc.imm_data set
to the value that A sent.