xprtrdma: Move credit update to RPC reply handler
Reduce work in the receive CQ handler, which can be run at hardware
interrupt level, by moving the RPC/RDMA credit update logic to the
RPC reply handler.
This has some additional benefits: More header sanity checking is
done before trusting the incoming credit value, and the receive CQ
handler no longer touches the RPC/RDMA header (the CPU stalls while
waiting for the header contents to be brought into the cache).
This further extends work begun by commit e7ce710a88
("xprtrdma:
Avoid deadlock when credit window is reset").
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
parent
3eb3581066
commit
eba8ff660b
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@ -736,7 +736,7 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
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struct rpc_xprt *xprt = rep->rr_xprt;
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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__be32 *iptr;
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int rdmalen, status;
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int credits, rdmalen, status;
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unsigned long cwnd;
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/* Check status. If bad, signal disconnect and return rep to pool */
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@ -871,8 +871,14 @@ badheader:
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break;
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}
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credits = be32_to_cpu(headerp->rm_credit);
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if (credits == 0)
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credits = 1; /* don't deadlock */
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else if (credits > r_xprt->rx_buf.rb_max_requests)
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credits = r_xprt->rx_buf.rb_max_requests;
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cwnd = xprt->cwnd;
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xprt->cwnd = atomic_read(&r_xprt->rx_buf.rb_credits) << RPC_CWNDSHIFT;
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xprt->cwnd = credits << RPC_CWNDSHIFT;
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if (xprt->cwnd > cwnd)
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xprt_release_rqst_cong(rqst->rq_task);
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@ -49,6 +49,7 @@
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#include <linux/interrupt.h>
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#include <linux/slab.h>
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#include <linux/prefetch.h>
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#include <asm/bitops.h>
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#include "xprt_rdma.h"
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@ -298,17 +299,7 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc, struct list_head *sched_list)
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rep->rr_len = wc->byte_len;
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ib_dma_sync_single_for_cpu(rdmab_to_ia(rep->rr_buffer)->ri_id->device,
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rep->rr_iov.addr, rep->rr_len, DMA_FROM_DEVICE);
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if (rep->rr_len >= 16) {
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struct rpcrdma_msg *p = (struct rpcrdma_msg *)rep->rr_base;
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unsigned int credits = ntohl(p->rm_credit);
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if (credits == 0)
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credits = 1; /* don't deadlock */
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else if (credits > rep->rr_buffer->rb_max_requests)
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credits = rep->rr_buffer->rb_max_requests;
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atomic_set(&rep->rr_buffer->rb_credits, credits);
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}
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prefetch(rep->rr_base);
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out_schedule:
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list_add_tail(&rep->rr_list, sched_list);
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@ -480,7 +471,6 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
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case RDMA_CM_EVENT_DEVICE_REMOVAL:
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connstate = -ENODEV;
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connected:
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atomic_set(&rpcx_to_rdmax(ep->rep_xprt)->rx_buf.rb_credits, 1);
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dprintk("RPC: %s: %sconnected\n",
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__func__, connstate > 0 ? "" : "dis");
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ep->rep_connected = connstate;
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@ -1186,7 +1176,6 @@ rpcrdma_buffer_create(struct rpcrdma_buffer *buf, struct rpcrdma_ep *ep,
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buf->rb_max_requests = cdata->max_requests;
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spin_lock_init(&buf->rb_lock);
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atomic_set(&buf->rb_credits, 1);
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/* Need to allocate:
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* 1. arrays for send and recv pointers
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@ -248,7 +248,6 @@ struct rpcrdma_req {
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*/
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struct rpcrdma_buffer {
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spinlock_t rb_lock; /* protects indexes */
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atomic_t rb_credits; /* most recent server credits */
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int rb_max_requests;/* client max requests */
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struct list_head rb_mws; /* optional memory windows/fmrs/frmrs */
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struct list_head rb_all;
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