On 11/13/2015 05:46 AM, Christoph Hellwig wrote:
- ret = ib_post_send(ch->qp, &wr.wr, &bad_wr);
- if (ret)
- break;
+ if (i == n_rdma - 1) {
+ /* only get completion event for the last rdma read */
+ if (dir == DMA_TO_DEVICE)
+ wr->wr.send_flags = IB_SEND_SIGNALED;
+ wr->wr.next = NULL;
+ } else {
+ wr->wr.next = &ioctx->rdma_ius[i + 1].wr;
+ }
}
+ ret = ib_post_send(ch->qp, &ioctx->rdma_ius->wr, &bad_wr);
if (ret)
pr_err("%s[%d]: ib_post_send() returned %d for %d/%d\n",
__func__, __LINE__, ret, i, n_rdma);
Hello Christoph,
Chaining RDMA requests is a great idea. But it seems to me that this
patch is based on the assumption that posting multiple RDMA requests
either succeeds as a whole or fails as a whole. Sorry but I'm not sure
that the verbs API guarantees this. In the ib_srpt driver a QP can be
changed at any time into the error state and there might be drivers that
report an immediate failure in that case. I think even when chaining
RDMA requests that we still need a mechanism to wait until ongoing RDMA
transfers have finished if some but not all RDMA requests have been posted.
Bart.
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