Merge branch 'smc-datapath-opts'

Dust Li says:

====================
net/smc: some datapath performance optimizations

This series tries to improve the performance of SMC in datapath.

- patch #1, add sysctl interface to support tuning the behaviour of
  SMC in container environment.

- patch #2/#3, add autocorking support which is very efficient for small
  messages without trade-off for latency.

- patch #4, send directly on setting TCP_NODELAY, without wake up the
  TX worker, this make it consistent with clearing TCP_CORK.

- patch #5, this correct the setting of RMB window update limit, so
  we don't send CDC messages to update peer's RMB window too frequently
  in some cases.

- patch #6, implemented something like NAPI in SMC, decrease the number
  of hardirq when busy.

- patch #7, this moves TX work doing in the BH to the user context when
  sock_lock is hold by user.

With this patchset applied, we can get a good performance gain:
- qperf tcp_bw test has shown a great improvement. Other benchmarks like
  'netperf TCP_STREAM' or 'sockperf throughput' has similar result.
- In my testing environment, running qperf tcp_bw and tcp_lat, SMC behaves
  better then TCP in most all message size.

Here are some test results with the following testing command:
client: smc_run taskset -c 1 qperf smc-server -oo msg_size:1:64K:*2 \
		-t 30 -vu tcp_{bw|lat}
server: smc_run taskset -c 1 qperf

==== Bandwidth ====
 MsgSize        Origin SMC              TCP                SMC with patches
       1         0.578 MB/s      2.392 MB/s(313.57%)      2.561 MB/s(342.83%)
       2         1.159 MB/s      4.780 MB/s(312.53%)      5.162 MB/s(345.46%)
       4         2.283 MB/s     10.266 MB/s(349.77%)     10.122 MB/s(343.46%)
       8         4.668 MB/s     19.040 MB/s(307.86%)     20.521 MB/s(339.59%)
      16         9.147 MB/s     38.904 MB/s(325.31%)     40.823 MB/s(346.29%)
      32        18.369 MB/s     79.587 MB/s(333.25%)     80.535 MB/s(338.42%)
      64        36.562 MB/s    148.668 MB/s(306.61%)    158.170 MB/s(332.60%)
     128        72.961 MB/s    274.913 MB/s(276.80%)    316.217 MB/s(333.41%)
     256       144.705 MB/s    512.059 MB/s(253.86%)    626.019 MB/s(332.62%)
     512       288.873 MB/s    884.977 MB/s(206.35%)   1221.596 MB/s(322.88%)
    1024       574.180 MB/s   1337.736 MB/s(132.98%)   2203.156 MB/s(283.70%)
    2048      1095.192 MB/s   1865.952 MB/s( 70.38%)   3036.448 MB/s(177.25%)
    4096      2066.157 MB/s   2380.337 MB/s( 15.21%)   3834.271 MB/s( 85.58%)
    8192      3717.198 MB/s   2733.073 MB/s(-26.47%)   4904.910 MB/s( 31.95%)
   16384      4742.221 MB/s   2958.693 MB/s(-37.61%)   5220.272 MB/s( 10.08%)
   32768      5349.550 MB/s   3061.285 MB/s(-42.77%)   5321.865 MB/s( -0.52%)
   65536      5162.919 MB/s   3731.408 MB/s(-27.73%)   5245.021 MB/s(  1.59%)
==== Latency ====
 MsgSize        Origin SMC              TCP                SMC with patches
       1        10.540 us     11.938 us( 13.26%)         10.356 us( -1.75%)
       2        10.996 us     11.992 us(  9.06%)         10.073 us( -8.39%)
       4        10.229 us     11.687 us( 14.25%)          9.996 us( -2.28%)
       8        10.203 us     11.653 us( 14.21%)         10.063 us( -1.37%)
      16        10.530 us     11.313 us(  7.44%)         10.013 us( -4.91%)
      32        10.241 us     11.586 us( 13.13%)         10.081 us( -1.56%)
      64        10.693 us     11.652 us(  8.97%)          9.986 us( -6.61%)
     128        10.597 us     11.579 us(  9.27%)         10.262 us( -3.16%)
     256        10.409 us     11.957 us( 14.87%)         10.148 us( -2.51%)
     512        11.088 us     12.505 us( 12.78%)         10.206 us( -7.95%)
    1024        11.240 us     12.255 us(  9.03%)         10.631 us( -5.42%)
    2048        11.485 us     16.970 us( 47.76%)         10.981 us( -4.39%)
    4096        12.077 us     13.948 us( 15.49%)         11.847 us( -1.90%)
    8192        13.683 us     16.693 us( 22.00%)         13.336 us( -2.54%)
   16384        16.470 us     23.615 us( 43.38%)         16.519 us(  0.30%)
   32768        22.540 us     40.966 us( 81.75%)         22.452 us( -0.39%)
   65536        34.192 us     73.003 us(113.51%)         33.916 us( -0.81%)

------------
Test environment notes:
1. Testing is run on 2 VMs within the same physical host
2. The NIC is ConnectX-4Lx, using SRIOV, and passing through 2 VFs to the
   2 VMs respectively.
3. To decrease jitter, VM's vCPU are binded to each physical CPU, and those
   physical CPUs are all isolated using boot parameter `isolcpus=xxx`
4. The queue number are set to 1, and interrupt from the queue is binded to
   CPU0 in the guest
====================

Signed-off-by: David S. Miller <[email protected]>

Author: davem330

Documentation/networking/smc-sysctl.rst

@@ -0,0 +1,23 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========
+SMC Sysctl
+=========
+
+/proc/sys/net/smc/* Variables
+==============================
+
+autocorking_size - INTEGER
+	Setting SMC auto corking size:
+	SMC auto corking is like TCP auto corking from the application's
+	perspective of view. When applications do consecutive small
+	write()/sendmsg() system calls, we try to coalesce these small writes
+	as much as possible, to lower total amount of CDC and RDMA Write been
+	sent.
+	autocorking_size limits the maximum corked bytes that can be sent to
+	the under device in 1 single sending. If set to 0, the SMC auto corking
+	is disabled.
+	Applications can still use TCP_CORK for optimal behavior when they
+	know how/when to uncork their sockets.
+
+	Default: 64K

include/net/netns/smc.h

@@ -14,5 +14,9 @@ struct netns_smc {
 	struct smc_stats_rsn		*fback_rsn;
 
 	bool				limit_smc_hs;	/* constraint on handshake */
+#ifdef CONFIG_SYSCTL
+	struct ctl_table_header		*smc_hdr;
+#endif
+	unsigned int			sysctl_autocorking_size;
 };
 #endif

net/smc/Makefile

@@ -4,4 +4,4 @@ obj-$(CONFIG_SMC)	+= smc.o
 obj-$(CONFIG_SMC_DIAG)	+= smc_diag.o
 smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
 smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
-smc-y += smc_tracepoint.o
+smc-y += smc_tracepoint.o smc_sysctl.o

net/smc/af_smc.c

@@ -51,6 +51,7 @@
 #include "smc_close.h"
 #include "smc_stats.h"
 #include "smc_tracepoint.h"
+#include "smc_sysctl.h"
 
 static DEFINE_MUTEX(smc_server_lgr_pending);	/* serialize link group
 						 * creation on server
@@ -192,12 +193,27 @@ void smc_unhash_sk(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(smc_unhash_sk);
 
+/* This will be called before user really release sock_lock. So do the
+ * work which we didn't do because of user hold the sock_lock in the
+ * BH context
+ */
+static void smc_release_cb(struct sock *sk)
+{
+	struct smc_sock *smc = smc_sk(sk);
+
+	if (smc->conn.tx_in_release_sock) {
+		smc_tx_pending(&smc->conn);
+		smc->conn.tx_in_release_sock = false;
+	}
+}
+
 struct proto smc_proto = {
 	.name		= "SMC",
 	.owner		= THIS_MODULE,
 	.keepalive	= smc_set_keepalive,
 	.hash		= smc_hash_sk,
 	.unhash		= smc_unhash_sk,
+	.release_cb	= smc_release_cb,
 	.obj_size	= sizeof(struct smc_sock),
 	.h.smc_hash	= &smc_v4_hashinfo,
 	.slab_flags	= SLAB_TYPESAFE_BY_RCU,
@@ -210,6 +226,7 @@ struct proto smc_proto6 = {
 	.keepalive	= smc_set_keepalive,
 	.hash		= smc_hash_sk,
 	.unhash		= smc_unhash_sk,
+	.release_cb	= smc_release_cb,
 	.obj_size	= sizeof(struct smc_sock),
 	.h.smc_hash	= &smc_v6_hashinfo,
 	.slab_flags	= SLAB_TYPESAFE_BY_RCU,
@@ -2795,8 +2812,8 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
 		    sk->sk_state != SMC_CLOSED) {
 			if (val) {
 				SMC_STAT_INC(smc, ndly_cnt);
-				mod_delayed_work(smc->conn.lgr->tx_wq,
-						 &smc->conn.tx_work, 0);
+				smc_tx_pending(&smc->conn);
+				cancel_delayed_work(&smc->conn.tx_work);
 			}
 		}
 		break;
@@ -3273,9 +3290,17 @@ static int __init smc_init(void)
 		goto out_sock;
 	}
 
+	rc = smc_sysctl_init();
+	if (rc) {
+		pr_err("%s: sysctl_init fails with %d\n", __func__, rc);
+		goto out_ulp;
+	}
+
 	static_branch_enable(&tcp_have_smc);
 	return 0;
 
+out_ulp:
+	tcp_unregister_ulp(&smc_ulp_ops);
 out_sock:
 	sock_unregister(PF_SMC);
 out_proto6:
@@ -3303,6 +3328,7 @@ static int __init smc_init(void)
 static void __exit smc_exit(void)
 {
 	static_branch_disable(&tcp_have_smc);
+	smc_sysctl_exit();
 	tcp_unregister_ulp(&smc_ulp_ops);
 	sock_unregister(PF_SMC);
 	smc_core_exit();

net/smc/smc.h

@@ -29,6 +29,7 @@
 #define SMC_MAX_ISM_DEVS	8	/* max # of proposed non-native ISM
 					 * devices
 					 */
+#define SMC_AUTOCORKING_DEFAULT_SIZE	0x10000	/* 64K by default */
 
 extern struct proto smc_proto;
 extern struct proto smc_proto6;
@@ -192,6 +193,7 @@ struct smc_connection {
 						 * - dec on polled tx cqe
 						 */
 	wait_queue_head_t	cdc_pend_tx_wq; /* wakeup on no cdc_pend_tx_wr*/
+	atomic_t		tx_pushing;     /* nr_threads trying tx push */
 	struct delayed_work	tx_work;	/* retry of smc_cdc_msg_send */
 	u32			tx_off;		/* base offset in peer rmb */
 
@@ -211,6 +213,10 @@ struct smc_connection {
 						 * data still pending
 						 */
 	char			urg_rx_byte;	/* urgent byte */
+	bool			tx_in_release_sock;
+						/* flush pending tx data in
+						 * sock release_cb()
+						 */
 	atomic_t		bytes_to_rcv;	/* arrived data,
 						 * not yet received
 						 */

net/smc/smc_cdc.c

@@ -48,9 +48,19 @@ static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
 		conn->tx_cdc_seq_fin = cdcpend->ctrl_seq;
 	}
 
-	if (atomic_dec_and_test(&conn->cdc_pend_tx_wr) &&
-	    unlikely(wq_has_sleeper(&conn->cdc_pend_tx_wq)))
-		wake_up(&conn->cdc_pend_tx_wq);
+	if (atomic_dec_and_test(&conn->cdc_pend_tx_wr)) {
+		/* If user owns the sock_lock, mark the connection need sending.
+		 * User context will later try to send when it release sock_lock
+		 * in smc_release_cb()
+		 */
+		if (sock_owned_by_user(&smc->sk))
+			conn->tx_in_release_sock = true;
+		else
+			smc_tx_pending(conn);
+
+		if (unlikely(wq_has_sleeper(&conn->cdc_pend_tx_wq)))
+			wake_up(&conn->cdc_pend_tx_wq);
+	}
 	WARN_ON(atomic_read(&conn->cdc_pend_tx_wr) < 0);
 
 	smc_tx_sndbuf_nonfull(smc);
@@ -350,8 +360,12 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
 	/* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
 	if ((diff_cons && smc_tx_prepared_sends(conn)) ||
 	    conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
-	    conn->local_rx_ctrl.prod_flags.urg_data_pending)
-		smc_tx_sndbuf_nonempty(conn);
+	    conn->local_rx_ctrl.prod_flags.urg_data_pending) {
+		if (!sock_owned_by_user(&smc->sk))
+			smc_tx_pending(conn);
+		else
+			conn->tx_in_release_sock = true;
+	}
 
 	if (diff_cons && conn->urg_tx_pend &&
 	    atomic_read(&conn->peer_rmbe_space) == conn->peer_rmbe_size) {

net/smc/smc_core.c

@@ -1988,7 +1988,7 @@ static struct smc_buf_desc *smc_buf_get_slot(int compressed_bufsize,
  */
 static inline int smc_rmb_wnd_update_limit(int rmbe_size)
 {
-	return min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2);
+	return max_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2);
 }
 
 /* map an rmb buf to a link */

net/smc/smc_sysctl.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  smc_sysctl.c: sysctl interface to SMC subsystem.
+ *
+ *  Copyright (c) 2022, Alibaba Inc.
+ *
+ *  Author: Tony Lu <[email protected]>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <net/net_namespace.h>
+
+#include "smc.h"
+#include "smc_sysctl.h"
+
+static struct ctl_table smc_table[] = {
+	{
+		.procname       = "autocorking_size",
+		.data           = &init_net.smc.sysctl_autocorking_size,
+		.maxlen         = sizeof(unsigned int),
+		.mode           = 0644,
+		.proc_handler	= proc_douintvec,
+	},
+	{  }
+};
+
+static __net_init int smc_sysctl_init_net(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = smc_table;
+	if (!net_eq(net, &init_net)) {
+		int i;
+
+		table = kmemdup(table, sizeof(smc_table), GFP_KERNEL);
+		if (!table)
+			goto err_alloc;
+
+		for (i = 0; i < ARRAY_SIZE(smc_table) - 1; i++)
+			table[i].data += (void *)net - (void *)&init_net;
+	}
+
+	net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table);
+	if (!net->smc.smc_hdr)
+		goto err_reg;
+
+	net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
+
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static __net_exit void smc_sysctl_exit_net(struct net *net)
+{
+	unregister_net_sysctl_table(net->smc.smc_hdr);
+}
+
+static struct pernet_operations smc_sysctl_ops __net_initdata = {
+	.init = smc_sysctl_init_net,
+	.exit = smc_sysctl_exit_net,
+};
+
+int __init smc_sysctl_init(void)
+{
+	return register_pernet_subsys(&smc_sysctl_ops);
+}
+
+void smc_sysctl_exit(void)
+{
+	unregister_pernet_subsys(&smc_sysctl_ops);
+}

net/smc/smc_sysctl.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  smc_sysctl.c: sysctl interface to SMC subsystem.
+ *
+ *  Copyright (c) 2022, Alibaba Inc.
+ *
+ *  Author: Tony Lu <[email protected]>
+ *
+ */
+
+#ifndef _SMC_SYSCTL_H
+#define _SMC_SYSCTL_H
+
+#ifdef CONFIG_SYSCTL
+
+int smc_sysctl_init(void);
+void smc_sysctl_exit(void);
+
+#else
+
+int smc_sysctl_init(void)
+{
+	return 0;
+}
+
+void smc_sysctl_exit(void) { }
+
+#endif /* CONFIG_SYSCTL */
+
+#endif /* _SMC_SYSCTL_H */