Commit 2b877fc5 authored by Chuck Lever's avatar Chuck Lever
Browse files

SUNRPC: Reduce thread wake-up rate when receiving large RPC messages 



With large NFS WRITE requests on TCP, I measured 5-10 thread wake-
ups to receive each request. This is because the socket layer
calls ->sk_data_ready() frequently, and each call triggers a
thread wake-up. Each recvmsg() seems to pull in less than 100KB.

Have the socket layer hold ->sk_data_ready() calls until the full
incoming message has arrived to reduce the wake-up rate.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 89d2d9fb

net/sunrpc/svcsock.c

+11 −1
Original line number Diff line number Diff line
@@ -1089,6 +1089,9 @@ static void svc_tcp_fragment_received(struct svc_sock *svsk) 
	/* If we have more data, signal svc_xprt_enqueue() to try again */

	svsk->sk_tcplen = 0;

	svsk->sk_marker = xdr_zero;



	smp_wmb();

	tcp_set_rcvlowat(svsk->sk_sk, 1);

}



/**
@@ -1178,10 +1181,17 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp) 
		goto err_delete;

	if (len == want)

		svc_tcp_fragment_received(svsk);

	else

	else {

		/* Avoid more ->sk_data_ready() calls until the rest

		 * of the message has arrived. This reduces service

		 * thread wake-ups on large incoming messages. */

		tcp_set_rcvlowat(svsk->sk_sk,

				 svc_sock_reclen(svsk) - svsk->sk_tcplen);



		trace_svcsock_tcp_recv_short(&svsk->sk_xprt,

				svc_sock_reclen(svsk),

				svsk->sk_tcplen - sizeof(rpc_fraghdr));

	}

	goto err_noclose;

error:

	if (len != -EAGAIN)