Commit 3079e342 authored by D. Wythe's avatar D. Wythe Committed by David S. Miller
Browse files

net/smc: Make smc_tcp_listen_work() independent 

In multithread and 10K connections benchmark, the backend TCP connection
established very slowly, and lots of TCP connections stay in SYN_SENT
state.

Client: smc_run wrk -c 10000 -t 4 http://server



the netstate of server host shows like:
    145042 times the listen queue of a socket overflowed
    145042 SYNs to LISTEN sockets dropped

One reason of this issue is that, since the smc_tcp_listen_work() shared
the same workqueue (smc_hs_wq) with smc_listen_work(), while the
smc_listen_work() do blocking wait for smc connection established. Once
the workqueue became congested, it's will block the accept() from TCP
listen.

This patch creates a independent workqueue(smc_tcp_ls_wq) for
smc_tcp_listen_work(), separate it from smc_listen_work(), which is
quite acceptable considering that smc_tcp_listen_work() runs very fast.

Signed-off-by: default avatarD. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 429c83c7

net/smc/af_smc.c

+11 −2
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ static DEFINE_MUTEX(smc_client_lgr_pending); /* serialize link group 
						 * creation on client

						 */



static struct workqueue_struct	*smc_tcp_ls_wq;	/* wq for tcp listen work */

struct workqueue_struct	*smc_hs_wq;	/* wq for handshake work */

struct workqueue_struct	*smc_close_wq;	/* wq for close work */
@@ -2227,7 +2228,7 @@ static void smc_clcsock_data_ready(struct sock *listen_clcsock) 
	lsmc->clcsk_data_ready(listen_clcsock);

	if (lsmc->sk.sk_state == SMC_LISTEN) {

		sock_hold(&lsmc->sk); /* sock_put in smc_tcp_listen_work() */

		if (!queue_work(smc_hs_wq, &lsmc->tcp_listen_work))

		if (!queue_work(smc_tcp_ls_wq, &lsmc->tcp_listen_work))

			sock_put(&lsmc->sk);

	}

}
@@ -3024,9 +3025,14 @@ static int __init smc_init(void) 
		goto out_nl;



	rc = -ENOMEM;



	smc_tcp_ls_wq = alloc_workqueue("smc_tcp_ls_wq", 0, 0);

	if (!smc_tcp_ls_wq)

		goto out_pnet;



	smc_hs_wq = alloc_workqueue("smc_hs_wq", 0, 0);

	if (!smc_hs_wq)

		goto out_pnet;

		goto out_alloc_tcp_ls_wq;



	smc_close_wq = alloc_workqueue("smc_close_wq", 0, 0);

	if (!smc_close_wq)
@@ -3097,6 +3103,8 @@ static int __init smc_init(void) 
	destroy_workqueue(smc_close_wq);

out_alloc_hs_wq:

	destroy_workqueue(smc_hs_wq);

out_alloc_tcp_ls_wq:

	destroy_workqueue(smc_tcp_ls_wq);

out_pnet:

	smc_pnet_exit();

out_nl:
@@ -3115,6 +3123,7 @@ static void __exit smc_exit(void) 
	smc_core_exit();

	smc_ib_unregister_client();

	destroy_workqueue(smc_close_wq);

	destroy_workqueue(smc_tcp_ls_wq);

	destroy_workqueue(smc_hs_wq);

	proto_unregister(&smc_proto6);

	proto_unregister(&smc_proto);