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xprtrdma: Use new CQ API for RPC-over-RDMA client receive CQs 

Calling ib_poll_cq() to sort through WCs during a completion is a
common pattern amongst RDMA consumers. Since commit 14d3a3b249
("IB: add a proper completion queue abstraction"), WC sorting can
be handled by the IB core.

By converting to this new API, xprtrdma is made a better neighbor to
other RDMA consumers, as it allows the core to schedule the delivery
of completions more fairly amongst all active consumers.

Because each ib_cqe carries a pointer to a completion method, the
core can now post its own operations on a consumer's QP, and handle
the completions itself, without changes to the consumer.

xprtrdma's reply processing is already handled in a work queue, but
there is some initial order-dependent processing that is done in the
soft IRQ context before a work item is scheduled.

IB_POLL_SOFTIRQ is a direct replacement for the current xprtrdma
receive code path.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@broadcom.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2016-03-04 11:28:36 -05:00 committed by Anna Schumaker
parent 23826c7aea
commit 552bf22528
2 changed files with 21 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
net/sunrpc/xprtrdma/verbs.c
View File

@ -212,11 +212,18 @@ rpcrdma_update_granted_credits(struct rpcrdma_rep *rep)
atomic_set(&buffer->rb_credits, credits);
}
/**
* rpcrdma_receive_wc - Invoked by RDMA provider for each polled Receive WC
* @cq: completion queue (ignored)
* @wc: completed WR
*
*/
static void
rpcrdma_recvcq_process_wc(struct ib_wc *wc)
rpcrdma_receive_wc(struct ib_cq *cq, struct ib_wc *wc)
{
struct rpcrdma_rep *rep =
(struct rpcrdma_rep *)(unsigned long)wc->wr_id;
struct ib_cqe *cqe = wc->wr_cqe;
struct rpcrdma_rep *rep = container_of(cqe, struct rpcrdma_rep,
rr_cqe);
/* WARNING: Only wr_id and status are reliable at this point */
if (wc->status != IB_WC_SUCCESS)
@ -242,55 +249,20 @@ out_schedule:
out_fail:
if (wc->status != IB_WC_WR_FLUSH_ERR)
pr_err("RPC: %s: rep %p: %s\n",
__func__, rep, ib_wc_status_msg(wc->status));
pr_err("rpcrdma: Recv: %s (%u/0x%x)\n",
ib_wc_status_msg(wc->status),
wc->status, wc->vendor_err);
rep->rr_len = RPCRDMA_BAD_LEN;
goto out_schedule;
}
/* The wc array is on stack: automatic memory is always CPU-local.
*
* struct ib_wc is 64 bytes, making the poll array potentially
* large. But this is at the bottom of the call chain. Further
* substantial work is done in another thread.
*/
static void
rpcrdma_recvcq_poll(struct ib_cq *cq)
{
struct ib_wc *pos, wcs[4];
int count, rc;
do {
pos = wcs;
rc = ib_poll_cq(cq, ARRAY_SIZE(wcs), pos);
if (rc < 0)
break;
count = rc;
while (count-- > 0)
rpcrdma_recvcq_process_wc(pos++);
} while (rc == ARRAY_SIZE(wcs));
}
/* Handle provider receive completion upcalls.
*/
static void
rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
{
do {
rpcrdma_recvcq_poll(cq);
} while (ib_req_notify_cq(cq, IB_CQ_NEXT_COMP |
IB_CQ_REPORT_MISSED_EVENTS) > 0);
}
static void
rpcrdma_flush_cqs(struct rpcrdma_ep *ep)
{
struct ib_wc wc;
while (ib_poll_cq(ep->rep_attr.recv_cq, 1, &wc) > 0)
rpcrdma_recvcq_process_wc(&wc);
rpcrdma_receive_wc(NULL, &wc);
while (ib_poll_cq(ep->rep_attr.send_cq, 1, &wc) > 0)
rpcrdma_sendcq_process_wc(&wc);
}
@ -655,9 +627,9 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
goto out2;
}
cq_attr.cqe = ep->rep_attr.cap.max_recv_wr + 1;
recvcq = ib_create_cq(ia->ri_device, rpcrdma_recvcq_upcall,
rpcrdma_cq_async_error_upcall, NULL, &cq_attr);
recvcq = ib_alloc_cq(ia->ri_device, NULL,
ep->rep_attr.cap.max_recv_wr + 1,
0, IB_POLL_SOFTIRQ);
if (IS_ERR(recvcq)) {
rc = PTR_ERR(recvcq);
dprintk("RPC: %s: failed to create recv CQ: %i\n",
@ -665,14 +637,6 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
goto out2;
}
rc = ib_req_notify_cq(recvcq, IB_CQ_NEXT_COMP);
if (rc) {
dprintk("RPC: %s: ib_req_notify_cq failed: %i\n",
__func__, rc);
ib_destroy_cq(recvcq);
goto out2;
}
ep->rep_attr.send_cq = sendcq;
ep->rep_attr.recv_cq = recvcq;
@ -735,10 +699,7 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
ia->ri_id->qp = NULL;
}
rc = ib_destroy_cq(ep->rep_attr.recv_cq);
if (rc)
dprintk("RPC: %s: ib_destroy_cq returned %i\n",
__func__, rc);
ib_free_cq(ep->rep_attr.recv_cq);
rc = ib_destroy_cq(ep->rep_attr.send_cq);
if (rc)
@ -947,6 +908,7 @@ rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
}
rep->rr_device = ia->ri_device;
rep->rr_cqe.done = rpcrdma_receive_wc;
rep->rr_rxprt = r_xprt;
INIT_WORK(&rep->rr_work, rpcrdma_receive_worker);
return rep;
@ -1322,7 +1284,7 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
int rc;
recv_wr.next = NULL;
recv_wr.wr_id = (u64) (unsigned long) rep;
recv_wr.wr_cqe = &rep->rr_cqe;
recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
recv_wr.num_sge = 1;

1
net/sunrpc/xprtrdma/xprt_rdma.h
View File

@ -171,6 +171,7 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb)
struct rpcrdma_buffer;
struct rpcrdma_rep {
struct ib_cqe rr_cqe;
unsigned int rr_len;
struct ib_device *rr_device;
struct rpcrdma_xprt *rr_rxprt;