RDS: SA query optimization

SA query optimization
The fact is all QoS lanes share the same physical path
b/w an IP pair. The only difference is the service level
that affects the quality of service for each lane. With
that, we have the following optimization:

1. Lane 0 to issue SA query request to the SM. All other
lanes will wait for lane 0 to finish route resolution,
then copy in the resolved path and fill in its service
level.

2. One-side reconnect to reduce reconnect racing, thus
further reducing the number of SA queries to the SM.

Reducing brownout for non-zero lanes
In some case, RDMA CM is delaying the disconnect event
after switch/node failure and this is causing extra
brownout for RDS reconnection. The workaround is to have
lane 0 probe other lanes by sending a HB msg. If the lane
is down, this will cause a send completion error and an
immediate reconnect.

Orabug: 18801977

Signed-off-by: Bang Nguyen <[email protected]>
Signed-off-by: Mukesh Kacker <[email protected]>
(cherry picked from commit 8f84b1ff46e449e99c5fcf4d4f94dc2e8ea82cd7)
Signed-off-by: Jerry Snitselaar <[email protected]>

Author: Bang Nguyen

net/rds/connection.c

@@ -209,6 +209,7 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 	INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
 	INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
 	INIT_DELAYED_WORK(&conn->c_hb_w, rds_hb_worker);
+	INIT_DELAYED_WORK(&conn->c_reconn_w, rds_reconnect_timeout);
 	INIT_DELAYED_WORK(&conn->c_reject_w, rds_reject_worker);
 	INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
 	mutex_init(&conn->c_cm_lock);
@@ -577,15 +578,7 @@ void rds_conn_exit(void)
 				 rds_conn_message_info_retrans);
 }
 
-/*
- * Drop connections when the idled QoS connection not getting
- * disconnect event when the remote peer reboots.  This is causing
- * delayed reconnect, hence application brownout when the peer comes online.
- * The fix was to proactively drop and reconnect them when the base lane is
- * going through the reconnect to the reboot peer, in effect forcing all
- * the lanes to go through the reconnect at the same time.
- */
-static void rds_conn_shutdown_lanes(struct rds_connection *conn)
+static void rds_conn_probe_lanes(struct rds_connection *conn)
 {
 	struct hlist_head *head =
 		rds_conn_bucket(conn->c_laddr, conn->c_faddr);
@@ -598,7 +591,8 @@ static void rds_conn_shutdown_lanes(struct rds_connection *conn)
 			tmp->c_laddr == conn->c_laddr &&
 			tmp->c_tos != 0 &&
 			tmp->c_trans == conn->c_trans) {
-				rds_conn_drop(tmp);
+			if (rds_conn_up(tmp))
+				rds_send_hb(tmp, 0);
 		}
 	}
 	rcu_read_unlock();
@@ -616,11 +610,16 @@ void rds_conn_drop(struct rds_connection *conn)
 		conn->c_reconnect_warn = 1;
 		conn->c_reconnect_drops = 0;
 		conn->c_reconnect_err = 0;
+		conn->c_reconnect_racing = 0;
 		printk(KERN_INFO "RDS/IB: connection "
 			"<%u.%u.%u.%u,%u.%u.%u.%u,%d> dropped\n",
 			NIPQUAD(conn->c_laddr),
 			NIPQUAD(conn->c_faddr),
 			conn->c_tos);
+
+		if (conn->c_tos == 0)
+			rds_conn_probe_lanes(conn);
+
 	} else if ((conn->c_reconnect_warn) &&
 		   (now - conn->c_reconnect_start > 60)) {
 		printk(KERN_INFO "RDS/IB: re-connect "
@@ -633,9 +632,8 @@ void rds_conn_drop(struct rds_connection *conn)
 			conn->c_reconnect_err);
 		conn->c_reconnect_warn = 0;
 
-		/* see comment for rds_conn_shutdown_lanes() */
 		if (conn->c_tos == 0)
-			rds_conn_shutdown_lanes(conn);
+			rds_conn_probe_lanes(conn);
 	}
 	conn->c_reconnect_drops++;
 

net/rds/ib.c

@@ -410,7 +410,7 @@ static void rds_ib_send_gratuitous_arp(struct net_device	*out_dev,
 
 	/* Send multiple ARPs to improve reliability */
 	for (i = 0; i < rds_ib_active_bonding_arps; i++) {
-		arp_send(ARPOP_REQUEST, ETH_P_ARP,
+		arp_send(ARPOP_REPLY, ETH_P_ARP,
 			ip_addr, out_dev,
 			ip_addr, NULL,
 			dev_addr, NULL);
@@ -1719,8 +1719,14 @@ static int rds_ib_netdev_callback(struct notifier_block *self, unsigned long eve
 
 		break;
 	case NETDEV_DOWN:
-		INIT_DELAYED_WORK(&work->work, rds_ib_failover);
-		queue_delayed_work(rds_wq, &work->work, 0);
+		if (rds_ib_sysctl_active_bonding) {
+			INIT_DELAYED_WORK(&work->work, rds_ib_failover);
+			queue_delayed_work(rds_wq, &work->work, 0);
+		} else {
+			ip_config[port].port_state = RDS_IB_PORT_INIT;
+			ip_config[port].ip_active_port = port;
+			kfree(work);
+		}
 		break;
 	}
 

net/rds/ib.h

@@ -594,6 +594,7 @@ extern unsigned long rds_ib_sysctl_max_unsig_wrs;
 extern unsigned long rds_ib_sysctl_max_unsig_bytes;
 extern unsigned long rds_ib_sysctl_max_recv_allocation;
 extern unsigned int rds_ib_sysctl_flow_control;
+extern unsigned int rds_ib_sysctl_active_bonding;
 extern ctl_table rds_ib_sysctl_table[];
 
 #endif

net/rds/ib_cm.c

@@ -813,6 +813,8 @@ int rds_ib_cm_handle_connect(struct rdma_cm_id *cm_id,
 		} else if (rds_conn_state(conn) == RDS_CONN_CONNECTING) {
 			unsigned long now = get_seconds();
 
+			conn->c_reconnect_racing++;
+
 			/*
 			 * after 15 seconds, give up on existing connection
 			 * attempts and make them try again.  At this point

net/rds/ib_sysctl.c

@@ -61,6 +61,7 @@ static unsigned long rds_ib_sysctl_max_unsig_wr_max = 64;
  */
 
 unsigned int rds_ib_sysctl_flow_control = 0;
+unsigned int rds_ib_sysctl_active_bonding = 1;
 
 ctl_table rds_ib_sysctl_table[] = {
 	{
@@ -104,6 +105,13 @@ ctl_table rds_ib_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+	{
+		.procname       = "active_bonding",
+		.data           = &rds_ib_sysctl_active_bonding,
+		.maxlen         = sizeof(rds_ib_sysctl_active_bonding),
+		.mode           = 0644,
+		.proc_handler   = &proc_dointvec,
+	},
 	{ }
 };
 

net/rds/rdma_transport.c

@@ -31,6 +31,7 @@
  *
  */
 #include <rdma/rdma_cm.h>
+#include <rdma/rdma_cm_ib.h>
 
 #include "rdma_transport.h"
 #include "ib.h"
@@ -94,6 +95,40 @@ int rds_rdma_cm_event_handler(struct rdma_cm_id *cm_id,
 		if (rds_ib_apm_enabled)
 			rdma_set_timeout(cm_id, rds_ib_apm_timeout);
 
+		if (conn->c_tos && conn->c_reconnect) {
+			struct rds_ib_connection *base_ic =
+				conn->c_base_conn->c_transport_data;
+
+			mutex_lock(&conn->c_base_conn->c_cm_lock);
+			if (rds_conn_transition(conn->c_base_conn, RDS_CONN_UP,
+						RDS_CONN_UP)) {
+				ret = rdma_set_ib_paths(cm_id,
+					base_ic->i_cm_id->route.path_rec,
+					base_ic->i_cm_id->route.num_paths);
+				if (!ret) {
+					struct rds_ib_connection *ic =
+						conn->c_transport_data;
+
+					cm_id->route.path_rec[0].sl =
+						ic->i_sl;
+					cm_id->route.path_rec[0].qos_class =
+						conn->c_tos;
+					ret = trans->cm_initiate_connect(cm_id);
+				}
+			} else {
+				ret = 1;
+			}
+			mutex_unlock(&conn->c_base_conn->c_cm_lock);
+
+			if (ret) {
+				rds_conn_drop(conn);
+				ret = 0;
+			}
+
+			break;
+		}
+
+
 		/* XXX do we need to clean up if this fails? */
 		ret = rdma_resolve_route(cm_id,
 				rds_rdma_resolve_to_ms[conn->c_to_index]);
@@ -172,6 +207,10 @@ int rds_rdma_cm_event_handler(struct rdma_cm_id *cm_id,
 		break;
 
 	case RDMA_CM_EVENT_ADDR_ERROR:
+		if (conn)
+			rds_conn_drop(conn);
+		break;
+
 	case RDMA_CM_EVENT_CONNECT_ERROR:
 	case RDMA_CM_EVENT_UNREACHABLE:
 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
@@ -181,8 +220,14 @@ int rds_rdma_cm_event_handler(struct rdma_cm_id *cm_id,
 
 	case RDMA_CM_EVENT_REJECTED:
 		err = (int *)event->param.conn.private_data;
+
+		if (conn && event->status == RDS_REJ_CONSUMER_DEFINED &&
+		    *err <= 1)
+			conn->c_reconnect_racing++;
+
 		if (conn) {
-			if (event->status == RDS_REJ_CONSUMER_DEFINED && (*err) == 0) {
+			if (event->status == RDS_REJ_CONSUMER_DEFINED &&
+			    (*err) == 0) {
 				/* Rejection from RDSV3.1 */
 				if (!conn->c_tos) {
 					conn->c_proposed_version =

net/rds/rds.h

@@ -87,6 +87,7 @@ enum {
 #define RDS_RECV_REFILL		3
 
 #define RDS_RDMA_RESOLVE_TO_MAX_INDEX   5
+#define RDS_ADDR_RES_TM_INDEX_MAX 5
 
 struct rds_connection {
 	struct hlist_node	c_hash_node;
@@ -125,6 +126,7 @@ struct rds_connection {
 	struct delayed_work	c_conn_w;
 	struct delayed_work     c_reject_w;
 	struct delayed_work     c_hb_w;
+	struct delayed_work	c_reconn_w;
 	struct work_struct	c_down_w;
 	struct mutex		c_cm_lock;	/* protect conn state & cm */
 	wait_queue_head_t	c_waitq;
@@ -161,6 +163,8 @@ struct rds_connection {
 	unsigned int            c_route_to_base;
 
 	unsigned int		c_rdsinfo_pending;
+
+	unsigned int		c_reconnect_racing;
 };
 
 #define RDS_FLAG_CONG_BITMAP	0x01
@@ -867,6 +871,7 @@ void rds_send_worker(struct work_struct *);
 void rds_reject_worker(struct work_struct *);
 void rds_recv_worker(struct work_struct *);
 void rds_hb_worker(struct work_struct *);
+void rds_reconnect_timeout(struct work_struct *);
 void rds_connect_complete(struct rds_connection *conn);
 
 /* transport.c */

net/rds/threads.c

@@ -264,11 +264,35 @@ void rds_hb_worker(struct work_struct *work)
 	}
 }
 
+void rds_reconnect_timeout(struct work_struct *work)
+{
+	struct rds_connection *conn =
+		container_of(work, struct rds_connection, c_reconn_w.work);
+
+	/* if the higher IP has not reconnected, reset back to two-sided
+	 * reconnect.
+	 */
+	if (!rds_conn_up(conn)) {
+		rds_conn_drop(conn);
+		conn->c_reconnect_racing = 0;
+	}
+}
+
 void rds_shutdown_worker(struct work_struct *work)
 {
 	struct rds_connection *conn = container_of(work, struct rds_connection, c_down_w);
 
-	rds_conn_shutdown(conn, 1);
+
+	/* if racing is detected, lower IP backs off and let the higher IP
+	 * drives the reconnect (one-sided reconnect)
+	 */
+	if (conn->c_laddr < conn->c_faddr && conn->c_reconnect_racing) {
+		rds_conn_shutdown(conn, 0);
+		queue_delayed_work(rds_wq, &conn->c_reconn_w,
+				msecs_to_jiffies(5000));
+	} else
+		rds_conn_shutdown(conn, 1);
+
 }
 
 void rds_threads_exit(void)