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svcrdma: Maintain a Receive water mark

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Post more Receives when the number of pending Receives drops below
a water mark. The batch mechanism is disabled if the underlying
device cannot support a reasonably-sized Receive Queue.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2021-03-11 18:32:30 -05:00
parent 7b748c30cc
commit c558d47596
3 changed files with 14 additions and 3 deletions
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2
include/linux/sunrpc/svc_rdma.h
View File

@ -94,6 +94,8 @@ struct svcxprt_rdma {
spinlock_t sc_rw_ctxt_lock;
struct list_head sc_rw_ctxts;
u32 sc_pending_recvs;
u32 sc_recv_batch;
struct list_head sc_rq_dto_q;
spinlock_t sc_rq_dto_lock;
struct ib_qp *sc_qp;

10
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View File

@ -285,6 +285,7 @@ static bool svc_rdma_refresh_recvs(struct svcxprt_rdma *rdma,
ctxt->rc_temp = temp;
ctxt->rc_recv_wr.next = recv_chain;
recv_chain = &ctxt->rc_recv_wr;
rdma->sc_pending_recvs++;
}
if (!recv_chain)
return false;
@ -302,6 +303,8 @@ err_free:
bad_wr = bad_wr->next;
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
/* Since we're destroying the xprt, no need to reset
* sc_pending_recvs. */
return false;
}
@ -328,6 +331,8 @@ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
struct ib_cqe *cqe = wc->wr_cqe;
struct svc_rdma_recv_ctxt *ctxt;
rdma->sc_pending_recvs--;
/* WARNING: Only wc->wr_cqe and wc->status are reliable */
ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe);
@ -344,8 +349,9 @@ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
* to reduce the likelihood of replayed requests once the
* client reconnects.
*/
if (!svc_rdma_refresh_recvs(rdma, 1, false))
goto flushed;
if (rdma->sc_pending_recvs < rdma->sc_max_requests)
if (!svc_rdma_refresh_recvs(rdma, rdma->sc_recv_batch, false))
goto flushed;
/* All wc fields are now known to be valid */
ctxt->rc_byte_len = wc->byte_len;

5
net/sunrpc/xprtrdma/svc_rdma_transport.c
View File

@ -407,11 +407,14 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
newxprt->sc_max_req_size = svcrdma_max_req_size;
newxprt->sc_max_requests = svcrdma_max_requests;
newxprt->sc_max_bc_requests = svcrdma_max_bc_requests;
rq_depth = newxprt->sc_max_requests + newxprt->sc_max_bc_requests;
newxprt->sc_recv_batch = RPCRDMA_MAX_RECV_BATCH;
rq_depth = newxprt->sc_max_requests + newxprt->sc_max_bc_requests +
newxprt->sc_recv_batch;
if (rq_depth > dev->attrs.max_qp_wr) {
pr_warn("svcrdma: reducing receive depth to %d\n",
dev->attrs.max_qp_wr);
rq_depth = dev->attrs.max_qp_wr;
newxprt->sc_recv_batch = 1;
newxprt->sc_max_requests = rq_depth - 2;
newxprt->sc_max_bc_requests = 2;
}