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Commit 8301a2c0 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

xprtrdma: Limit work done by completion handler 



Sagi Grimberg <sagig@dev.mellanox.co.il> points out that a steady
stream of CQ events could starve other work because of the boundless
loop pooling in rpcrdma_{send,recv}_poll().

Instead of a (potentially infinite) while loop, return after
collecting a budgeted number of completions.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Acked-by: default avatarSagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 1c00dd07

net/sunrpc/xprtrdma/verbs.c

+6 −4
Original line number Diff line number Diff line
@@ -165,8 +165,9 @@ static int 
rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)

{

	struct ib_wc *wcs;

	int count, rc;

	int budget, count, rc;



	budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;

	do {

		wcs = ep->rep_send_wcs;
@@ -177,7 +178,7 @@ rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) 
		count = rc;

		while (count-- > 0)

			rpcrdma_sendcq_process_wc(wcs++);

	} while (rc == RPCRDMA_POLLSIZE);

	} while (rc == RPCRDMA_POLLSIZE && --budget);

	return 0;

}
@@ -254,8 +255,9 @@ static int 
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)

{

	struct ib_wc *wcs;

	int count, rc;

	int budget, count, rc;



	budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;

	do {

		wcs = ep->rep_recv_wcs;
@@ -266,7 +268,7 @@ rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) 
		count = rc;

		while (count-- > 0)

			rpcrdma_recvcq_process_wc(wcs++);

	} while (rc == RPCRDMA_POLLSIZE);

	} while (rc == RPCRDMA_POLLSIZE && --budget);

	return 0;

}

net/sunrpc/xprtrdma/xprt_rdma.h

+1 −0
Original line number Diff line number Diff line
@@ -74,6 +74,7 @@ struct rpcrdma_ia { 
 * RDMA Endpoint -- one per transport instance

 */



#define RPCRDMA_WC_BUDGET	(128)

#define RPCRDMA_POLLSIZE	(16)



struct rpcrdma_ep {