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Commit e340c2d6 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

xprtrdma: Reduce the doorbell rate (Receive) 



Post RECV WRs in batches to reduce the hardware doorbell rate per
transport. This helps the RPC-over-RDMA client scale better in
number of transports.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent d4550bbe

net/sunrpc/xprtrdma/verbs.c

+2 −0
Original line number Diff line number Diff line
@@ -1480,6 +1480,8 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp) 
	if (ep->rep_receive_count > needed)

		goto out;

	needed -= ep->rep_receive_count;

	if (!temp)

		needed += RPCRDMA_MAX_RECV_BATCH;



	count = 0;

	wr = NULL;

net/sunrpc/xprtrdma/xprt_rdma.h

+10 −0
Original line number Diff line number Diff line
@@ -205,6 +205,16 @@ struct rpcrdma_rep { 
	struct ib_recv_wr	rr_recv_wr;

};



/* To reduce the rate at which a transport invokes ib_post_recv

 * (and thus the hardware doorbell rate), xprtrdma posts Receive

 * WRs in batches.

 *

 * Setting this to zero disables Receive post batching.

 */

enum {

	RPCRDMA_MAX_RECV_BATCH = 7,

};



/* struct rpcrdma_sendctx - DMA mapped SGEs to unmap after Send completes

 */

struct rpcrdma_req;