SUNRPC: Mitigate cond_resched() in xprt_transmit() (6f9f1728) · Commits · 戴 / test

The original purpose of this expensive call is to prevent a long queue of requests from blocking other work. The cond_resched() call is unnecessary after just a single send operation. For longer queues, instead of invoking the kernel scheduler, simply release the transport send lock and return to the RPC scheduler. Signed-off-by:

Chuck Lever <chuck.lever@oracle.com> Signed-off-by:

Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprt.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -1513,10 +1513,13 @@ xprt_transmit(struct rpc_task *task)
		{
		struct rpc_rqst next, req = task->tk_rqstp;
		struct rpc_xprt *xprt = req->rq_xprt;
		int status;
		int counter, status;

		spin_lock(&xprt->queue_lock);
		counter = 0;
		while (!list_empty(&xprt->xmit_queue)) {
		if (++counter == 20)
		break;
		next = list_first_entry(&xprt->xmit_queue,
		struct rpc_rqst, rq_xmit);
		xprt_pin_rqst(next);
		@@ -1524,7 +1527,6 @@ xprt_transmit(struct rpc_task *task)
		status = xprt_request_transmit(next, task);
		if (status == -EBADMSG && next != req)
		status = 0;
		cond_resched();
		spin_lock(&xprt->queue_lock);
		xprt_unpin_rqst(next);
		if (status == 0) {

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