@@ -390,11 +390,13 @@ static void frwr_cid_init(struct rpcrdma_ep *ep,
*/
int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
{
+ struct ib_send_wr *post_wr, *send_wr = &req->rl_wr;
struct rpcrdma_ep *ep = r_xprt->rx_ep;
- struct ib_send_wr *post_wr;
struct rpcrdma_mr *mr;
+ unsigned int num_wrs;
- post_wr = &req->rl_wr;
+ num_wrs = 1;
+ post_wr = send_wr;
list_for_each_entry(mr, &req->rl_registered, mr_list) {
struct rpcrdma_frwr *frwr;
@@ -409,8 +411,19 @@ int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
frwr->fr_regwr.wr.send_flags = 0;
post_wr = &frwr->fr_regwr.wr;
+ ++num_wrs;
}
+ if ((kref_read(&req->rl_kref) > 1) || num_wrs > ep->re_send_count) {
+ send_wr->send_flags |= IB_SEND_SIGNALED;
+ ep->re_send_count = min_t(unsigned int, ep->re_send_batch,
+ num_wrs - ep->re_send_count);
+ } else {
+ send_wr->send_flags &= ~IB_SEND_SIGNALED;
+ ep->re_send_count -= num_wrs;
+ }
+
+ trace_xprtrdma_post_send(req);
return ib_post_send(ep->re_id->qp, post_wr, NULL);
}
@@ -1365,21 +1365,7 @@ static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb)
*/
int rpcrdma_post_sends(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
{
- struct ib_send_wr *send_wr = &req->rl_wr;
- struct rpcrdma_ep *ep = r_xprt->rx_ep;
- int rc;
-
- if (!ep->re_send_count || kref_read(&req->rl_kref) > 1) {
- send_wr->send_flags |= IB_SEND_SIGNALED;
- ep->re_send_count = ep->re_send_batch;
- } else {
- send_wr->send_flags &= ~IB_SEND_SIGNALED;
- --ep->re_send_count;
- }
-
- trace_xprtrdma_post_send(req);
- rc = frwr_send(r_xprt, req);
- if (rc)
+ if (frwr_send(r_xprt, req))
return -ENOTCONN;
return 0;
}
Send WRs can be signalled or unsignalled. A signalled Send WR always has a matching Send completion, while a unsignalled Send has a completion only if the Send WR fails. xprtrdma has a Send account mechanism that is designed to reduce the number of signalled Send WRs. This in turn mitigates the interrupt rate of the underlying device. RDMA consumers can't leave all Sends unsignaled, however, because providers rely on Send completions to maintain their Send Queue head and tail pointers. xprtrdma counts the number of unsignaled Send WRs that have been posted to ensure that Sends are signalled often enough to prevent the Send Queue from wrapping. This mechanism neglected to account for FastReg WRs, which are posted on the Send Queue but never signalled. As a result, the Send Queue wrapped on occasion, resulting in duplication completions of FastReg and LocalInv WRs. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> --- net/sunrpc/xprtrdma/frwr_ops.c | 17 +++++++++++++++-- net/sunrpc/xprtrdma/verbs.c | 16 +--------------- 2 files changed, 16 insertions(+), 17 deletions(-)